Serological tests of blood in the diagnosis of diseases

Serology is a section of immunology that studies antigen responses to serum antibodies.

Serological tests are a technique for studying specific antibodies or antigens in the blood serum of patients. They are based on responses of immunity. Widely apply these studies in the diagnosis of various infectious diseases and when determining the blood group of a person.

To whom is the serological examination of

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

Which material is examined by

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

- serum;

- saliva;

- fecal masses.

The material should be in the laboratory as soon as po

ssible. Otherwise, it can be stored in the refrigerator at a temperature of +4 or by adding a preservative.

Conducting the analysis sampling

It is not necessary to prepare the patient specifically for the collection of these analyzes. Research is safe. Blood sampling is performed in the morning hours on an empty stomach, both from the ulnar 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 many options for blood testing. One of them are serological tests of blood. This is a basic analysis conducted to identify certain microbes, viruses and infections, as well as the stage of development of the infectious process. Serologic blood tests for:

are used to determine the amount of antibodies against viruses and microbes present in the body. To do this, the antigen of the pathogen is added to the blood serum, after which the ongoing chemical reaction is evaluated;

- antigen determination by introducing antibodies into the blood;

- blood group definitions.

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

Serological tests: analyzes and their interpretation

An increase in the number of antigen-antibody complexes in the body indicates the presence of infection in the patient's body. Conducting 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 the pathogens, this indicates the absence of infection of the body. However, this happens rarely, since the appointment of serological analysis already indicates the detection of symptoms of an infection.

What can affect the result of the

analysis It is necessary to closely monitor the conditions in which blood is taken. Do not allow anything in the blood to enter the bloodstream. The day before the analysis should not overload the body with fatty foods, alcohol and sweet drinks. It is necessary to exclude stressful situations and reduce physical exertion. Biological material should be delivered to the laboratory as soon as possible, since prolonged storage of serum leads to partial inactivity of antibodies.

Serological Test Methods

In laboratory practice, a blood serological test is complementary to a bacteriological study. The main methods are presented:

1. The fluorescence reaction, which is carried out in two stages. First, antibodies in the circulating antigen complex are detected. Then an antiserum is applied to the control sample, followed by incubation of the preparations. The RIF is used for rapid detection of the causative agent of the disease in the test material. The results of the reactions are evaluated using a fluorescent microscope. The character of the luminescence, the shape, size of the objects is estimated.

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

- direct reactions used to detect antibodies in the patient's blood serum. A certain number of killed microbes is added to the serum and causes the formation of a precipitate in the form of flakes. Serological studies on typhoid fever involve carrying out a direct agglutination reaction;

- passive hemagglutination reactions based on the ability of red blood cells to adsorb the antigen on its surface and cause adhesion upon its contact with the antibody, and the precipitation of a visible precipitate. It is used in the process of diagnosing infectious diseases for the detection of hypersensitivity to certain drugs. When evaluating the results, the appearance of the sediment is taken into account. The precipitate in the form of a ring at the bottom of the tube indicates a negative reaction. Lace sediment with uneven edges indicates the presence of a particular infection.

3. Immunoenzymatic analysis, 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 changing its level. This research method has a number of advantages:

- very sensitive;

- used reagents - are universal, and they are stable for half a year;

- the process of accounting for the results of the analysis is automated.

The above listed serological test methods have some advantages over the bacteriological method. These methods allow to determine the antigens of pathogens in a few minutes or hours. Moreover, these studies can identify the antigens of the pathogen even after the 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 significance. The basis for the diagnosis still remain clinical data. Serologic tests are done to confirm the diagnosis if the reactions do not contradict the clinical picture. Weakly positive reactions of serological studies without a clinical picture confirming it can not be the basis for the diagnosis. Such results should be taken into account when the patient had a similar disease in the past and he underwent a course of appropriate treatment.

Determination of hereditary signs of blood, confirmation or disprofection of paternity, the study of hereditary and autoimmune diseases, the establishment of nature and the source of infection in epidemics - all this helps to identify serological blood tests. The interpretation of the results gives information on the presence of specific proteins to infections such as syphilis, hepatitis, HIV, toxoplasmosis, rubella, measles, typhoid fever.