What does a serological blood test show. What can you find out with a serological blood test? Serological examination of blood antigen with

A serological blood test is a fundamental research method carried out in order to quickly and reliably detect microbes, infections and viruses in the human body. In addition, thanks to this method, you can determine the entire list of existing diseases resulting from a decrease in immunity.

Due to the serological analysis, the blood taken from the patient is studied for HIV, syphilis and other dangerous ailments. In addition, the study is necessary in case of approval of the patient's blood group and to determine the specificity of proteins.

As noted earlier, the analysis is recommended for diagnosing infectious diseases and establishing the stage of the inflammatory process. Thanks to the serological chemical reaction, it is possible to determine the level of interaction between antigens and antibodies responsible for the result.

This analysis applies:

When determining the number of antibodies that fight the causative agent of the disease: during the analysis, the blood serum is mixed with the antigen of the causative agent of the disease, after which they look at the ongoing reaction.
The reverse situation is that a developing infection is detected due to the presence of antigens detected by adding antibodies to the blood.
In the case of establishing a blood group.

With poor blood clotting and in the case of hypercoagulability, dangerous consequences associated with cardiac activity can occur.

The need for serological testing increases when a patient is suspected of having a sexually transmitted infection or other disease. In the result of the passed analysis, there is information about the presence in the blood of antibodies to this type of bacteria or viruses. These are liver diseases, measles, human immunodeficiency virus, herpes, etc. If antibodies are detected, the doctor makes a conclusion to the patient and determines the further course of therapy. If necessary, additional research will be required.

The material is taken from the cubital vein. The analysis is taken on an empty stomach in the morning. However, before giving biochemical analysis for hepatitis, all brightly colored vegetables and fruits should be excluded from the daily diet. If you need to confirm the results of the finished analysis, you can assign a secondary examination without special training.

Transcription of serological analysis

Given laboratory research shown to patients with difficulty differential diagnosis various kinds of infections. In this case, only a serological analysis can determine the type of infectious agent and help the doctor determine the diagnosis of the disease. In addition, the great benefit of this technique is reflected in the selection drug therapy the patient, because the causative agents of many diseases vary greatly in their sensitivity to the action of antibiotics and other medicines.

Thanks to a serological study, it is easy to determine whether a person has a disease that was caused by a latent infection entering the body. After completing the procedure for collecting material, laboratory assistants perform a decoding of indicators that allow experienced doctors to fully investigate the pathologies that have arisen in the body. In the absence of antibodies in the blood, a person does not develop an infectious disease. In this case, the result of the analysis will be positive. But this rare case. As a rule, in the presence of symptoms of the disease, serological analysis serves as evidence of the presence of a dangerous pathology. In this case, the process is duplicated. Initially, the presence of small pathogens in the body is detected. Further, the degree of development of the inflammatory process is identified by the number of antibodies.

The norm in the implementation of this test is the zero content of antibodies. The value will always mean the presence of pathology in the body. In this regard, the patient needs to undergo additional studies to confirm the diagnosis.

Features of serological testing for syphilis, HIV and hepatitis

An analysis for syphilis involves the detection of proteins responsible for the entry into the human body of the causative agent of infection - treponema pale. The biological material in this case is blood serum. Before donating blood, 4 days in advance, you should stop taking heart medications and refuse any alcoholic products. It should be noted that infection can only be established after 1.5-2 months from the moment of infection. If this analysis performed by a pregnant woman, she must be prepared for a false positive result.

The basis for a serological analysis for hepatitis may be the following symptoms:

causeless fatigue and impotence of the body;
poor appetite or its absence;
vomit;
changes in the shade of urine and feces;
yellowness of the skin.

In addition, the diagnosis of hepatitis is considered necessary when undergoing a physical examination or during the examination during pregnancy.

If a person has a positive test result for HIV infection, this does not mean that he is infected with AIDS. If less than 2 months have passed since the infection, the presence of antibodies to the immunodeficiency virus in the blood cannot make it possible to draw a conclusion indicating the development of the disease. To do this, repeat the procedure. An HIV test is mandatory during pregnancy at the time of the first visit and at the 30th week of the term.

ELISA blood test

One of the most popular types of serological studies is enzyme immunoassay, which is carried out to effectively control the number of antigens and antibodies in human blood serum. In addition, using this method, it is possible to determine the content of hormones, immunological complexes and other biological components.

When bioorganic substances penetrate into the tissue and vital organs of a person, immunity does not allow their impact on health due to antibodies and immunoglobulins. As a result of their exposure, an antigen-antibody complex is formed in the body. Only its comprehensive analysis will be an important component of the ELISA method.

The patient's blood serves as the main material necessary for the study. In some cases, in order to recognize the type of disease or select therapy, cerebrospinal and amniotic fluid are taken for analysis. Enzyme immunoassay as an integral part of serology is based on a detailed study of blood molecules and immunoglobulins. Their feature is the ability to detect and destroy infectious agents together with a specific antigen.

The advantages of this method include the possibility of determining the disease at an early stage of its development, the speed and accuracy of the result, low cost and the exclusion of preparation for the study.

There are few disadvantages of the method: it is possible to obtain a false negative result, which requires further retesting.

Before taking any laboratory analysis, you must follow the rules of preparation. The collection of material should be carried out exclusively in sanitary conditions. In addition, it is necessary to prevent foreign substances from entering the blood. An important condition for each analysis for infections is blood donation exclusively on an empty stomach. At the same time, the day before the test, it is not recommended to eat fatty and spicy foods, alcoholic products and sweet drinks. In addition, it is necessary to avoid stressful situations and any physical exertion. In any case, before deciding to donate blood for research, you need to undergo a medical examination by your doctor.

After hearing the patient's complaints, the doctor will be able to recommend the advisability of taking a serological blood test.

Serology is a branch of immunology that studies the reactions of antigens to serum antibodies.

Serological testing is a technique for studying certain antibodies or antigens in the blood serum of patients. They are based on immune responses. These studies are widely used in the process of diagnosing various infectious diseases and defining a person.

Who is assigned a serological test

Serological analysis is prescribed for patients with suspected infectious disease. This analysis in conflicting situations with the diagnosis will help to establish the causative agent of the disease. Also, further treatment largely depends on the results of serological studies, since the determination of a specific microorganism contributes to the appointment of specific treatment.

What material is being tested

Serological studies involve the sampling of biological material from a patient in the form of:

blood serum;

Fecal matter.

material in as soon as possible should be in the lab. Otherwise, it can be stored in the refrigerator at a temperature of +4 or by adding a preservative.

Taking samples

It is not necessary to prepare the patient for the collection of these analyzes. Research is safe. A blood test is taken in the morning on an empty stomach, both from the cubital vein and from the ring finger. After sampling, the blood should be placed in a sterile, sealed tube.

Serological blood test

Human blood performs many functions in the body and has a very wide field of activity, so there are also many options for blood testing. One of them is serological blood tests. This is a basic analysis carried out in order to recognize certain microbes, viruses and infections, as well as the stage of development of the infectious process. Serological blood tests are used for:

Determining the amount of antibodies against viruses and microbes in the body. To do this, the antigen of the causative agent of the disease is added to the blood serum, after which the ongoing chemical reaction is evaluated;

Determination of antigen by introduction;

Definition of blood group.

Serological blood tests are always prescribed twice - to determine the dynamics of the disease. A single determination of the interaction of antigens and antibodies indicates only the fact of infection. To reflect the full picture, where an increase in the number of connections between immunoglobulins and antigens can be observed, a re-examination is necessary.

Serological studies: analyzes and their interpretation

An increase in the number of antigen-antibody complexes in the body indicates the presence of an infection in the patient's body. Carrying out specific chemical reactions with the growth of these indicators in the blood contribute to the definition of the disease and its stage.

If the result of the analysis shows the absence of antibodies to pathogens, then this indicates the absence of infection in the body. However, this rarely happens, since the appointment of a serological analysis already indicates the detection of symptoms of a particular infection.

What can affect the result of the analysis

You should carefully monitor the conditions in which the blood is taken. It is impossible to allow something foreign to enter the blood. The day before the analysis, you should not overload the body with fatty foods, alcohol and sugary drinks. Avoid stressful situations and reduce physical activity. Biological material should be delivered to the laboratory as soon as possible, since long-term storage of serum leads to partial inactivity of antibodies.

Serological research methods

In laboratory practice, serological blood testing is additional to the main methods presented:

1. Fluorescence reaction, which is carried out in two stages. First, antibodies are detected in the circulating antigen complex. Then, antiserum is applied to the control sample, followed by incubation of the preparations. RIF is used to quickly detect the causative agent of the disease in the test material. The results of the reactions are evaluated using a fluorescent microscope. Evaluated the nature of the glow, shape, size of objects.

2. The agglutination reaction, which is a simple agglutination reaction of discrete antigens using antibodies. Allocate:

Direct reactions used to detect antibodies in the patient's blood serum. A certain amount of killed microbes is added to the serum and causes the formation of a precipitate in the form of flakes. Serological studies for typhoid fever imply a direct agglutination reaction;

Passive hemagglutonation reactions, based on the ability of erythrocytes to adsorb the antigen on their surface and cause sticking when it comes into contact with the antibody, and the loss of a visible precipitate. It is used in the process of diagnosing infectious diseases to detect hypersensitivity to certain drugs. When evaluating the results, it takes into account appearance draft. A precipitate in the form of a ring at the bottom of the tube indicates a negative reaction. Lacy sediment with uneven edges indicates the presence of an infection.

3. which is based on the principle of attaching an enzyme label to antibodies. This allows you to see the result of the reaction by the appearance of enzyme activity or by a change in its level. This research method has a number of advantages:

Very sensitive;

The reagents used are universal, and they are stable for six months;

The process of recording the results of the analysis is automated.

The above serological research methods have some advantages over the bacteriological method. These methods allow you to determine the antigens of pathogens in a few minutes or hours. Moreover, these studies can detect the antigens of the pathogen even after treatment and the death of the bacteria that cause it.

Diagnostic value of the study

The results of serological studies are a valuable diagnostic method, but have an auxiliary value. The basis for the diagnosis is still clinical data. Serological studies are done to confirm the diagnosis, if the reactions do not contradict the clinical picture. Weakly positive studies without confirming it clinical picture cannot form the basis for a diagnosis. Such results should be taken into account when the patient had a similar disease in the past and received appropriate treatment.

Determining the hereditary signs of blood, confirming or refuting paternity, studying hereditary and autoimmune diseases, establishing the nature and source of infection in epidemics - all this helps to identify serological blood tests. The interpretation of the results provides information on the presence of specific proteins for infections such as syphilis, hepatitis, HIV, toxoplasmosis, rubella, measles, typhoid fever.

This analysis applies:

When determining the number of antibodies that fight the causative agent of the disease: during the analysis, the blood serum is mixed with the antigen of the causative agent of the disease, after which they look at the ongoing reaction.
The reverse situation is that a developing infection is detected due to the presence of antigens detected by adding antibodies to the blood.
In the case of establishing a blood group.

With poor blood clotting and in the case of hypercoagulability, dangerous consequences associated with cardiac activity can occur.

The material is taken from the cubital vein. The analysis is taken on an empty stomach in the morning. However, before taking a biochemical analysis for hepatitis, all brightly colored vegetables and fruits should be excluded from the daily diet. If you need to confirm the results of the finished analysis, you can assign a secondary examination without special training.

Transcription of serological analysis

This laboratory study is indicated for patients with difficulties in the differential diagnosis of various infections. In this case, only a serological analysis can determine the type of infectious agent and help the doctor determine the diagnosis of the disease. In addition, the enormous benefit of this technique is reflected in the selection of drug therapy for the patient, because the causative agents of many diseases differ greatly in their sensitivity to the action of antibiotics and other drugs.

Thanks to a serological study, it is easy to determine whether a person has a disease that was caused by a latent infection entering the body. After completing the procedure for collecting material, laboratory assistants perform a decoding of indicators that allow experienced doctors to fully investigate the pathologies that have arisen in the body. In the absence of antibodies in the blood, a person does not develop an infectious disease. In this case, the result of the analysis will be positive. But this is a rare case. As a rule, in the presence of symptoms of the disease, serological analysis serves as evidence of the presence of a dangerous pathology. In this case, the process is duplicated. Initially, the presence of small pathogens in the body is detected. Further, the degree of development of the inflammatory process is identified by the number of antibodies.

Features of serological testing for syphilis, HIV and hepatitis

An analysis for syphilis involves the detection of proteins responsible for the entry into the human body of the causative agent of infection - treponema pale. The biological material in this case is blood serum. Before donating blood, 4 days in advance, you should stop taking heart medications and refuse any alcoholic products. It should be noted that infection can only be established after 1.5-2 months from the moment of infection. If this analysis is performed by a pregnant woman, she should be prepared for a false positive result.

The basis for a serological analysis for hepatitis may be the following symptoms:

causeless fatigue and impotence of the body;
poor appetite or its absence;
vomit;
changes in the shade of urine and feces;
yellowness of the skin.

In addition, the diagnosis of hepatitis is considered necessary when undergoing a physical examination or during the examination during pregnancy.

ELISA blood test

The advantages of this method include the possibility of determining the disease at an early stage of its development, the speed and accuracy of the result, low cost and the exclusion of preparation for the study.

There are few disadvantages of the method: it is possible to obtain a false negative result, which requires further retesting.

After hearing the patient's complaints, the doctor will be able to recommend the advisability of taking a serological blood test.

SEROLOGICAL STUDIES(lat. serum serum + Greek logos doctrine) - methods of immunology that study the specific properties of human or animal blood in order to detect antigens or antibodies using serological reactions.

S.'s beginning and. put at the end of the last century, after it was found that the connection of an antigen with an antibody (see Antigen - antibody reaction) is accompanied by a number of phenomena available to visual observation - agglutination (see), precipitation (see) or lysis. There was a possibility of specific recognition of antigens (see) or antibodies (see) if one of these components is known.

In 1897, F. Vidal reported that the blood serum of patients with typhoid fever selectively agglutinates typhoid bacteria and therefore this reaction (see Vidal reaction) can be applied to the lab. diagnosis of typhoid fever. In the same year, it was shown that culture filtrates of plague, typhoid and cholera bacteria, when combined with the corresponding immune sera, form flakes or precipitates.

The precipitation reaction proved to be suitable for the detection of any protein antigens. In 1900-1901. K. Landsteiner found that in human erythrocytes there are two different antigens (A and B), and in blood sera two agglutinins (a and P), which contributed to the use of the hemagglutination reaction to determine blood groups (see).

The agglutination reaction for determining the blood type and Rh factor is used in obstetric practice, with blood transfusions and tissue transplantation. Antibodies against the Rh factor (see) are incomplete antibodies, they are not capable of direct reaction with Rh-positive erythrocytes, therefore, to detect them, use the Coombs reaction (see Coombs reaction), based on the detection of incomplete antibodies using antiglobulin sera. To erythrocytes of known specificity, the test blood serum is added, and after that, antiglobulin serum against IgG ( indirect reaction Coombs). Fab-fragments of incomplete antibodies of the studied blood serum attach to erythrocytes, and antibodies against IgG attach to free Fc-fragments of these antibodies, and erythrocyte agglutination occurs. For the diagnosis of hemolytic anemia, the direct Coombs reaction is used. In the body of such patients, red blood cells combine with antibodies circulating in the blood against the Rh factor. To identify them, antibodies against IgG are added to the erythrocytes taken from the patient. The appearance of erythrocyte agglutination confirms the diagnosis of the disease.

The hemagglutination inhibition reaction - RTGA (see Hemagglutination) - is based on the phenomenon of prevention (inhibition) of hemagglutination of erythrocytes by viruses by immune serum. The phenomenon of a virus hemagglutination is not serol. reaction and occurs as a result of the connection of the virus with erythrocyte receptors, however, HTA is a serological test used to detect and titrate antiviral antibodies. RTGA is the main method of serodiagnosis of influenza, measles, rubella, mumps, tick-borne encephalitis and other viral infections, the causative agents of which have hemagglutinating properties.

The reaction of passive, or indirect, hemagglutinations, It uses erythrocytes or neutral synthetic materials (eg, latex particles), on the surface of which antigens (bacterial, viral, tissue) or antibodies are sorbed (see Boyden reaction). Their agglutination occurs when the appropriate sera or antigens are added. RBCs sensitized with antigens are called antigenic erythrocyte diagnosticum and are used to detect and titrate antibodies. Erythrocytes sensitized by antibodies are called immunoglobulin erythrocyte diagnosticums (see) and are used to detect antigens:

The passive hemagglutination reaction is used to diagnose diseases caused by bacteria (typhoid and paratyphoid, dysentery, brucellosis, plague, cholera, etc.), protozoa (malaria) and viruses (influenza, adenovirus infections, tick-borne encephalitis, Crimean hemorrhagic fever, etc.) . The reaction of passive hemagglutination in sensitivity is not inferior to the method of isolation of the virus in arenoviral diseases (see), in particular with lymphocytic choriomeningitis. The viral antigen of lymphocytic choriomeningitis is detected in virus carriers (house mice) in a passive hemagglutination reaction with suspensions of extracted organs diluted tens of thousands of times. With salmonellosis, bacteria are detected in the passive hemagglutination reaction at a concentration of up to several hundred microbial bodies in 1 g of feces, dysentery bacteria in food products are detected when the content of 1 g of material is at least 500 microbial bodies.

The passive hemagglutination reaction is used in the diagnosis and prevention of viral hepatitis B. In the Soviet Union, to detect the HBs antigen (see Australian antigen) in the blood of patients with acute hepatitis B, a diagnosticum is produced, which is chicken erythrocytes sensitized with goat immunoglobulin against the HBs antigen. A drop of diagnosticum is combined with an equal volume of blood serum of the examined people, and if the HBs antigen is present in it, agglutination occurs. The reaction is capable of capturing up to 1.5 ng/ml of HBs antigen. To detect HBs antibodies, erythrocytes with HBs antigen adsorbed on them, isolated from the blood of patients, are used. The reaction of passive hemagglutination is also used to detect hypersensitivity of the patient to drugs and hormones, for example, penicillin or insulin. In this case, erythrocytes of the 0 blood group of a person are sensitized with a medicinal substance and then used to detect agglutinins to it in the patient's blood serum.

The reaction of passive hemagglutination is used to detect gonadotropin in the urine to establish pregnancy (see Chorionic gonadotropin). To do this, the standard serum for this hormone is incubated with the urine under study. With the subsequent addition of erythrocytes with the hormone adsorbed on them, agglutination does not occur (positive answer), since the hormone contained in the urine neutralized agglutinating antibodies.

Reactions based on the phenomenon of precipitation

They are used to detect a wide variety of antigens and antibodies. The simplest example of a qualitative reaction is the formation of an opaque precipitation band at the border of antigen deposition on an antibody in a test tube. Various types of precipitation reactions in semi-liquid gels of agar or agarose are widely used (the method of double immunodiffusion according to Ouchterlon, the method of radial immunodiffusion, immunoelectrophoresis), which are both qualitative and quantitative (see Immunodiffusion, Immunoelectrophoresis).

To set up double immunodiffusion, a layer of melted gel is poured onto a glass plate and, after hardening, holes with a diameter of 1.5-3 mm are cut out. The test antigens are placed in the wells arranged in a circle, and the immune serum of known specificity is placed in the central well. Diffusing towards each other, homologous sera and antigens form a precipitate. With radial immunodiffusion (according to the Mancini method), immune serum is introduced into agar. The antigen placed in the wells diffuses through the agar, and as a result of precipitation with immune serum, opaque rings are formed around the wells, the outer diameter of which is proportional to the concentration of the antigen. A modification of this reaction is used in the diagnosis of influenza for the recognition of IgM and IgG antibodies (see Immunoglobulins). Influenza antigen is introduced into the agar, and blood serum into the wells. Then the plates are treated with immune sera against IgM or IgG antibodies, which helps to identify the reaction of the corresponding antibodies with antigens. The method allows you to simultaneously determine the titers of antibodies and their belonging to a certain class of immunoglobulins.

A type of immunoelectrophoresis is radioimmunophoresis. In this case, after the electrophoretic separation of the antigens, the groove cut parallel to the movement of the antigens in the gel is first filled with the immune serum labeled with radioactive iodine against the antigens to be determined, and then the immune serum against the IgG antibodies, which precipitates the formed complexes of the antibody with the antigen. All unbound reagents are washed out, and the antigen-antibody complex is detected by autoradiography (see).

Complement reactions. Reactions with participation of a complement (see) are based on ability of a subcomponent of a complement of Cl (Clq) and then other components of a complement to join immune complexes.

The complement fixation reaction allows you to titrate antigens or antibodies according to the degree of complement fixation by the antigen-antibody complex. This reaction consists of two phases: the interaction of the antigen with the test blood serum (test system) and the interaction of hemolytic serum with sheep erythrocytes (indicator system). With a positive reaction in the test system, complement fixation occurs, and then when adding antibody-sensitized erythrocytes, hemolysis is not observed (see Complement fixation reaction). The reaction is widely used for serodiagnosis of visceral syphilis (see Wasserman reaction) and viral infections (see Virological studies).

Cytolysis. Antibodies against cellular structures can, with the participation of complement, dissolve the cells that carry these structures. RBC lysis can be easily assessed by the degree and intensity of hemoglobin release. The lysis of nuclear cells is estimated by counting the percentage of dead cells that do not stain with methylene blue. Often also use radioactive chromium, to-ry previously chemically associated with cells. The number of destroyed cells is determined by the amount of unbound chromium released during cell lysis.

The reaction of radial hemolysis of erythrocytes can occur in the gel. A suspension of sheep erythrocytes is placed in an agarose gel, adding a complement there; wells are made in a layer frozen on glass and hemolytic serum is added to them. A zone of hemolysis will form around the wells as a result of radial diffusion of antibodies. The radius of the hemolysis zone is directly proportional to the serum titer. If any antigen is adsorbed on erythrocytes, for example, glycoprotein hemagglutinin of the influenza virus, rubella or tick-borne encephalitis, then the phenomenon of hemolysis by immune sera to these viruses can be reproduced. The reaction of radial hemolysis in gel has found application in the diagnosis of viral infections due to the ease of staging, insensitivity to serum inhibitors, and the ability to titrate blood serum according to the diameter of the hemolysis zone without resorting to serial dilutions.

immune adhesion. Erythrocytes, platelets and other blood cells have receptors for the third complement component (C3) on their surface. If an appropriate immune serum and complement are added to an antigen (bacteria, viruses, etc.), then an antigen-antibody complex is formed, covered with the C3 component of the complement. When mixed with platelets, due to the C3 component of the complement, the antigen-antibody complex will settle on the cells and cause them to agglutinate (see Immune adhesion). This reaction is used to determine the antigens of the HLA system (see. Transplant immunity) and in the study of a number of viral infections(tick-borne encephalitis, dengue fever), to-rye are accompanied by immunopatol. processes and circulation in the blood of viral antigens in combination with antibodies.

The neutralization reaction is based on the ability of antibodies to neutralize certain specific functions of macromolecular or soluble antigens, for example, enzyme activity, bacterial toxins, pathogenicity of viruses. In bacteriology, this reaction is used to detect antistreptolysins, antistreptokinase, and antistaphylolysins. The reaction of neutralization of toxins can be assessed by biol. effect, for example, anti-tetanus and anti-botulinum sera are titrated (see Toxin - antitoxin reaction). A mixture of toxin and antiserum administered to animals prevents their death. Various variants of the neutralization reaction are used in virology. By mixing the viruses with the appropriate antiserum and introducing this mixture into animals or cell cultures, the pathogenicity of the viruses is neutralized.

Reactions using chemical and physical labels

The immunofluorescence developed by Koons (AN Coons) in 1942 consists in use for serol. reactions of sera labeled with fluorochrome (see Immunofluorescence). The serum labeled with fluorochrome forms an antigen-antibody complex with the antigen, which becomes available for observation under a microscope in ultraviolet rays that excite the fluorochrome glow. The direct immunofluorescence reaction is used to study cellular antigens, detect virus in infected cells, and detect bacteria and rickettsia in smears. So, for the diagnosis of rabies, the prints of pieces of the brain of animals suspected of carrying a virus are treated with luminescent anti-rabies serum. With a positive result, clumps of bright green color are observed in the protoplasm of nerve cells. The rapid diagnosis of influenza, parainfluenza and adenovirus infection is based on the detection of virus antigens in the cells of the imprints from the nasal mucosa.

The method of indirect immunofluorescence is more widely used, based on the detection of an antigen-antibody complex using luminescent immune serum against IgG antibodies and used to detect not only antigens, but also titration of antibodies. The method has found application in the serodiagnosis of herpes, cytomegalips, Lassa fever. In the laboratory, a stock of preparations of antigen-containing cells, for example, virus-infected VERO cells or acetone-fixed chicken fibroblasts, should be kept at -20°C. The studied blood serum is layered on the preparations, the preparation is placed in a thermostat at f 37 ° to form immune complexes, and then, after washing off unbound reagents, these complexes are detected with labeled luminescent serum against human globulins. Using labeled immune sera against IgM or IgG antibodies, it is possible to differentiate the type of antibodies and detect an early immune response by the presence of IgM antibodies.

In an enzyme - an immunological method apply the antibodies conjugated with enzymes, hl. arr. horseradish peroxidase or alkaline phosphatase. To detect the connection of labeled serum with an antigen, a substrate is added, which is decomposed by an enzyme attached to the serum with the appearance of staining in yellow-brown (peroxidase) or yellow-green (phosphatase) color. Enzymes are also used that decompose not only the chromogenic, but also the lumogenic substrate. In this case, with a positive reaction, a glow appears. Like immunofluorescence, enzyme immunoassay is used to detect antigens in cells or to titrate antibodies on antigen-containing cells.

The most popular type of enzyme-immunological method is immunosorption. On a solid carrier, the Crimea can be cellulose, polyacrylamide, dextran and various plastics, adsorb the antigen. More often, the surface of micropanels wells serves as a carrier. The test blood serum is added to the wells with the sorbed antigen, then the antiserum labeled with the enzyme and the substrate. Positive results are taken into account by the change in the color of the liquid medium. To detect antigens, antibodies are adsorbed onto the carrier, then the test material is introduced into the wells and a reaction is detected with enzyme-labeled antimicrobial serum.

The radioimmunological method is based on the use of a radioisotope label of antigens or antibodies. It was originally developed as a specific method for measuring the level of circulating hormones in the blood. The test system was an isotope-labeled hormone (antigen) and antiserum to it. If a material containing the desired hormone is added to such an antiserum, then it will bind part of the antibodies, with the subsequent introduction of the labeled titrated hormone, a reduced amount of it compared to the control will bind to the antibodies. The result is evaluated by comparing the curves of bound and unbound radioactive label. This kind of method is called the competitive reaction. There are other modifications of the radioimmunological method. Radioimmunoassay is the most sensitive method for detecting antigens and antibodies used to determine hormones, medicinal substances and antibiotics, for the diagnosis of bacterial, viral, rickettsial, protozoal diseases, the study of blood proteins, tissue antigens.

Comparative characteristics and use of serological research methods in medical practice

S.'s methods and. continuously improved in the direction of increased sensitivity and versatility of use. Initially serol. diagnosis was based on the detection of antibodies. With the advent of the mid-20th century reactions of immunofluorescence and passive hemagglutination, which have greater sensitivity, it became possible to detect not only antibodies, but also antigen directly in the material from patients. Enzyme-immunological and radioimmunological methods, in sensitivity by 2-3 orders of magnitude greater than immunofluorescence and passive hemagglutination, approach the methods of biol. detection of bacteria and viruses. The scope of their application for the detection of both antigens and antibodies is theoretically unlimited.

Serodiagnosis inf. disease is based on the appearance of antibodies to an isolated or suspected pathogen, regardless of whether the pathogen was detected in the acute stage of the disease. Examine pairs of blood sera taken at the onset of the disease and 2-3 weeks. later. An increase in antibodies in the second blood serum by at least 4 times compared with the first is diagnostically significant. It also matters what class of immunoglobulins antibodies are represented by. IgM antibodies are found at the end of the acute period of the disease and in early stage convalescence. IgG antibodies appear at later stages of convalescence and circulate for a long time. If a woman in the first trimester of pregnancy is found to have IgM antibodies to the rubella virus, then this serves as a basis for terminating the pregnancy, since during this period the fetus is especially sensitive to the virus. At different inf. diseases selectively use the most specific and convenient methods.

S. i. widely used in epidemiology. Systematic collection and research of samples of blood of various groups of the population allow to understand contacts of the population with a source of activators inf. diseases. The study of the level of collective immunity allows you to identify high-risk groups and plan vaccination activities, study the geographical distribution of infections. S. i. different age groups of the population made it possible, for example, to retrospectively identify the circulation different options influenza virus at certain times.

S. i. have great importance in the study of hereditary diseases (see) and autoimmune diseases, accompanied by the appearance of tissue- and organ-specific antibodies that destroy the corresponding target cells, as well as in oncology for the detection of tumor antigens. Thus, the immunodiagnosis of liver cancer is based on the determination of alpha-fetoprotein and other embryonic antigens in the blood serum of patients by immunodiffusion and radioimmunoassay methods.

Considerable progress of science in studying of fine antigenic structure of cellular antigens, antigens of bacteria and viruses is reached thanks to application in serol. reactions of monoclonal antibodies, to-rye it is possible to receive to separate antigen determinants.

Bibliography: Methods of research in immunology, ed. I. Lefkovits and B. Pernis, trans. from English, M., 1981; Guide to Immunology, ed. O. E. Vyazova and Sh. X. Khodzhaev. Moscow, 1973. Guidelines for Clinical laboratory diagnostics, ed. V. V. Menshikov. Moscow, 1982. Immunology, ed. by J.-F. Bach, N.Y., 1978.

S. Ya. Gaidamovich.

Diagnosis is the most important step in the treatment of any disease. Depending on the correct diagnosis, there is not only successful treatment, but also the ability to prevent the development of complications and comorbidities. What is a serological test? This is a method of diagnostic analysis of a patient's biological sample for the presence of antibodies and antigens. The test allows you to identify dozens of diseases, the phase of the disease and control treatment.

What is the study for?

This type of medical research is widely used in various fields of medicine. The complement fixation reaction or RSK is aimed at identifying specific cells in the blood serum, antibodies that the body produces to fight infections and viruses.

Isoserological study is aimed at determining the blood type, Rh factor and other parameters of the patient's blood.

A serological blood test is used in gynecology to detect sexually transmitted diseases. Serological titration is also used for a comprehensive examination of expectant mothers (toxoplasmosis, HIV, syphilis, etc.). When registering pregnant women, this is a mandatory test.
In pediatrics, serological tests are used to confirm the diagnosis of "children's" diseases (chickenpox, rubella, measles, etc.), if the symptoms are not pronounced and there is no way to determine the disease according to clinical indications.
Serological studies allow venereologists to quickly and accurately make a diagnosis. With similar symptoms and complaints, a blood test can detect antibodies to syphilis, giardiasis, ureplasmosis, chlamydia, herpes and other diseases.
Gastroenergy, hepatologists, and infectious disease specialists use a serological blood test to diagnose viral hepatitis.
Any infectious or viral disease may be suspected by a therapist. For confirmation, serological tests for specific antibodies in the body are used. An analysis is carried out for encephalitis, brucellosis, whooping cough, dengue virus, immunodeficiency virus, allergies, etc.
Serological diagnosis for hospitalization plays an important role. This diagnostic method can show at what stage of development the disease is, and whether immediate admission to the hospital is required or outpatient treatment is sufficient.

A sample of saliva and feces can be used as biological material for research, but the patient's venous blood is most often used. Analysis for serological reactions should be taken from the cubital vein under laboratory conditions. Before taking the test, you should consult with your doctor and prepare.

Preparation for analysis

This type of research is carried out in both municipal and commercial institutions. It is better to make a choice in favor of the laboratory that has the most modern equipment and has only positive feedback about its work. For busy patients, the laboratory can provide blood sampling services at the RSK at home.

In this case, the patient does not have to waste time on the road, and queues are excluded.

Preparing for the fence venous blood includes several general rules. Before the test, you can not eat food, that is, the analysis is taken on an empty stomach. When donating blood, you need to be in a state of calm and not worry. Before the procedure, you should not undergo other procedures (radiography, ultrasound examination etc.). A few weeks before blood sampling, in agreement with the attending physician, the appointment is canceled medicines. Some recommendations depend on the disease being tested for. For example, when testing for hepatitis 2 days before the analysis, fatty foods and alcohol are excluded from the diet.

Fluorescence reaction

One of the types of serological reactions is fluorescence or RIF. This research method is carried out using a reagent that highlights the desired antibodies in the blood serum. To set up a direct-type serological reaction or PIF, specific antibodies are labeled with a fluorescent substance. This is the fastest type of research, which is carried out in one stage.

Another method, which is called indirect or RNIF, is carried out in 2 stages. On the first, specific cells (antibodies) do not have fluorescent labels, and on the second, appropriate labeled antibodies are used to detect the antigen-antibody complex. The glow reaction appears only after binding with a specific antibody. The result of the manipulations is evaluated by a special device that evaluates the intensity of radiation, and also determines the shape and size of the objects under study. The infectious agent is determined with a certainty of 90-95% depending on the type and stage of the disease.

Linked immunosorbent assay

For the study of ELISA, serological reactions are carried out using unique stable reagents. Labeled substances are attached to a specific (desired) type of antibody. As a result, serology provides a qualitative or quantitative assessment of a patient's blood sample. If the substrate does not have expressed markers, the result is considered negative. In the case of a qualitative study, a positive result means only the presence of antibodies in a biological sample.

Serodiagnosis with quantitative detection of antibody cells gives a more complete picture. By the sum of the detected cells, the doctor can tell if the disease is in initial stage, acute or it is an exacerbation of the chronic form of the disease. When making a diagnosis, the clinical picture and complaints of the patient are also taken into account.

Research Features

When testing for brucellosis, blood serum is monitored for self-retention without antigen. This improves the reliability of the test. The result of the analysis for brucellosis can be positive, negative or unexpressed, that is, questionable. When obtaining doubtful results, repeated blood sampling is recommended. Brucellosis is also diagnosed based on the results of blood cultures, bone marrow and cerebrospinal fluid tests.

Advantages and disadvantages of serology

Diagnosis using serological methods is widely used in modern medicine. This test is especially relevant in the detection of viral and infectious diseases. The same type of analysis is used in geographic screenings and medical examinations to prevent epidemiological outbreaks.

Serological assays have a number of advantages.

A serological test of any type is highly reliable.
Serology tests are carried out fairly quickly. The result of the RSC is known in a day, and you can get it via the Internet without leaving your home. In special cases, with inpatient treatment, the test is carried out within a few hours.
RSK allows you to control the development of the disease, and monitor the effectiveness of the treatment.
Serological research methods are inexpensive and available to patients.

Serological tests also have some disadvantages. In order for the examination to give the most reliable information, a blood test should be carried out taking into account the time incubation period illness.

Herpes simplex types 1 and 2 can be determined only 2 weeks after infection, and an immunodeficiency virus test is carried out 1, 3 and 6 months after contact with the patient.

The reliability of the study can be affected by the human factor. If the patient neglects the rules for preparing for the study or the laboratory assistant made a mistake in processing the blood sample, a false or doubtful result may be obtained. This situation occurs in about 5% of cases. As a rule, the attending physician, on the basis of clinical indications, easily calculates the RSK error.

Serological blood testing is a modern and reliable way to detect such dangerous diseases as HIV, hepatitis, brucellosis, STDs, etc. This branch of medicine is aimed at studying human blood plasma and its immunological properties. The serological method is widely used, and the cost of research in private laboratories is relatively low. For analysis, modern equipment is used, which minimizes the influence of the human factor on the results of research.

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