Modern medicine has specific diagnostic methods that make it possible to establish the etiology of diseases in people based on the definition of the pathogen, genetically foreign substances that stimulate the immune response, nucleic acids, as well as the allergic and immune shifts that occur due to its action. Today, in immunology and virology, RIA is widely used, that is, radioimmunoassay, statement of purpose, components, progress, accounting which, we will consider in this article. This analysis is able to determine antigens as a result of their interaction with antibodies.
Definition
RIA is a method for diagnosing biologically active substances in liquids, which is based on the reaction of antigens with antibodies when using radionuclide-labeled substances similar to them, which have special binding systems. After their interaction, an immune complex is formed, which is separated and its radioactivity is studied. It is known that radioimmunoassay is performed using standard reagent kits.
Each reagent is able to determine the concentration of one particular substance. The biological fluid taken from a person is mixed with a reagent, after a lapse of the incubation period, the separation of free and bound radioactive material occurs, then radiometry and calculation of the results are carried out. An iodine isotope is used to label substances. It is labeled and added in a certain amount.
Application
Radioimmunoassay is widely used in medicine and microbiology. With its help, a diagnosis of heart and vascular diseases, diseases of the endocrine and other body systems is carried out. RIAs are also often used to identify the causes of infertility, pathology of the fetus. In oncology, this analysis is carried out in order to identify markers of neoplasms in order to be able to control the effectiveness of treatment. In immunology, RIA is used to study the presence of immunoglobulins, enzymes, proteins, and so on in the blood. Today, this analysis allows you to identify the concentration of various hormones up to a millionth part of one gram. Thus, a radioimmune blood test widely used in cardiology, oncology, endocrinology, gynecology and virology.
RIA methods
It is customary to distinguish several analysis methods, depending on the nature of the reaction:
- The non-competitive method is characterized by such reaction components as standard and detectable antigens, buffer solution, antibodies that are labeled with the isotope, certain antibodies that bind to the sorbent. Antigen is added to the antibodies, which is being investigated. After incubation, antigen-antibody complexes appear, the sorbent is washed, labeled antibodies are added, which enter into contact with the antigen in the complex. Radioactivity depends on the concentration of antigen that is being studied.
- Competitive radioimmunoassay is determined by antigen competition. Here there are reaction components such as control and detectable antigens, buffer solution, specific antibodies that bind to the sorbent, as well as an antigen labeled with an isotope. Diagnosis begins with the input of the antigen that is being investigated. An antigen-antibody complex forms on the sorbent. Then the sorbent is washed, and the labeled antigen is introduced. In this case, he enters into a relationship with the antibody. Using counters measure the reaction and the amount of radioactivity. It will be in inverse proportion to the amount of antigen in the sample.
- An indirect method is the most common. In this case, a radioimmunoassay analysis of the reaction components has such as control and test serum, antigens or antibodies that are bound on the sorbent, antibodies labeled with isotopes, buffer solutions. Antibodies or antigens that are diagnosed react with antigens or antibodies that are bound on the sorbent. Then the incubate is removed, labeled antibodies are introduced, which enter into contact with antigen-antibody complexes.
Analysis Methodology
So, radioimmunoassay is carried out using special reagents. Kits are standard, so any errors or violations are not allowed. Diagnostic results are reliable. The analysis is carried out in the morning, for this, venous blood is taken from a person. In the laboratory, serum is separated from the blood, which will be used for RIA. This serum is mixed with reagents. The resulting mixture is incubated at a given temperature in a thermostat.
Free and bound isotopes are separated in the resulting mixture. After that, the resulting material is examined, and the results are calculated. The mechanism of radioimmunoassay has several options. The technique described above is RIA liquid phase, since all components have a liquid state. There is RIA and solid phase, where antibodies are placed in a carrier that does not dissolve in the liquid.
Diagnostic Availability
Using this diagnostic method in medicine is becoming more and more popular every year. Recently, radioimmunoassay has become the standard diagnostic method that can be prescribed by a doctor when making a final diagnosis. For a long time, this type of analysis was carried out only in laboratories, today it has become a common research method. But RIA requires the use of expensive equipment (gamma counters), and reagent kits have a short operational life. All this is the main disadvantage of such an analysis that determines its expensive cost.
In addition, recently, RIA have begun to supplant more modern research methods that do not require interaction with isotopes. These include enzyme immunoassay. Thus, RIA is desirable in many clinics. In large cities and diagnostic centers, it has long been used, but in conventional hospitals in small cities this analysis is practically not used because of its high cost.
RIA advantages
Radioimmunoassay has many advantages. It is quite specific and has a high sensitivity, which makes it possible to determine the presence of biologically active substances in incredibly small quantities. This analysis is carried out very simply, a person only needs to donate venous blood. The test results are 100% accurate and ready the very next day. RIA can also be easily automated. Thus, this analysis allows you to identify proteins that are the waste products of infectious bacteria, which indicates the presence of infection in the body.
Diagnostics in Virology
The most promising RIA is for virology, because it allows you to quickly identify viral pathogens. This is due to the fact that in recent years the number of incidence of various infections is growing, which spread at a high speed, causing death among people. This is especially true for countries that do not have high social and economic development (countries of the Far East), radioimmunoassay is simply irreplaceable here . Microbiology also applies this diagnostic method to detect infectious diseases that cause pathogenic bacteria. For example, RIAs are widely used to detect typhoid fever. In the first days of the disease before the appointment of treatment, it is necessary to conduct a study of feces and vomit. However, the diagnostic results will be obtained after a long time. Here RIA comes to the rescue, the analysis allows you to quickly identify the causative agent of the disease. The person donates blood, the next day the results of the study are ready. This analysis helps in making an accurate diagnosis.
Summary
Radioimmunoassay is currently one of the most sensitive diagnostic methods. It is used to analyze any substance against which antibodies can be obtained. This method makes it possible to make many samples in the smallest volume of the studied liquid, as well as to record results as soon as possible, since it can be fully automated. This analysis was developed in the fifties of the last century by Solomon Berson. Thirty years later, it became widespread. To date, RIA has no one hundred percent alternative, since the analysis has a high sensitivity. RIA is used in various branches of medicine, as well as in microbiology and virology.
In the end
The use of the method in virology is very important today, as it makes it possible to study the spread of infections, make an accurate diagnosis and prescribe specific treatment. This problem is especially relevant for countries that have a low level of economy and social development. Also, this analysis allows you to identify the amount of hormones and enzymes in the human body. In order to obtain reliable results, the researched only needs to donate blood for analysis. Medicine does not stand still, along with radioimmune analysis, new research methods appear, but RIA continues to be one of the leading in medical diagnostics.