What Is an Antibody Assay?

The purpose of specific antibody detection is first to assist clinical diagnosis. It is also an indicator of efficacy and prognosis in certain diseases, observation of the effect of vaccination, and in the epidemiological investigation of infectious diseases. The detection of specific antibodies has special Important meaning.

Antibody detection

The purpose of specific antibody testing is first to assist clinical diagnosis, and in some diseases to observe the effect and

In the immune response,

There are many methods for antibody detection, in addition to the traditional

First of all, when antibody testing is used for diagnosis, the incidence of the disease in the patient's area and the conditions closely related to the disease, such as the level of antibodies in normal human serum, should be considered.

For many diseases

Generally, diagnosis

In order to ensure the specificity and sensitivity of the test, both granular antigens, tissue extracts, peptide antigens, and recombinant antigens must be purified, otherwise non-specific reactions are likely to occur. In the application of labeled immunoassay, the background value can be increased, which greatly affects the accuracy of the test. In the detection of autoantibodies, many antigens are extracted from tissues. Pay more attention to the purification of antigens. Because the same antigen component can exist between different tissues and organs, the same autoimmune disease can detect several different autoantibodies, and the same autoantibodies can appear in different autoimmune diseases, which affects the specificity of the test. Therefore, it reminds us that there is still a lot of work to be done in the extraction, purification and synthesis of specific antigens in this regard, which is a long-term task. It must also be pointed out that no matter which antibody is detected, the specificity and sensitivity of the antigen can be affected by the fragment or composition of the antigen used. Therefore, when a new antigen is used, strict control is needed before its application value can be determined.

It must be clear that different detection methods have different sensitivity, accuracy, and reproducibility, and the quality of the kits are different, all affect the test results. When applying or establishing a method, the concentration of all components in the detection system must be strictly titrated to select the most appropriate concentration range. For example, enzyme-linked immunosorbent assay (ELISA), the concentration of antigen and enzyme conjugates is low, and the final absorbance value is too small, which is prone to false negatives. Sensitive ranges can significantly affect the reliability of the results.

Antibodies are classified as protective antibodies and non-protective antibodies. The level of some antibodies decreases and even disappears shortly after reaching a peak. Some antibodies can persist for a long period of time. For example, hepatitis B core antibody (anti-HBc), the positive rate can be as high as about 70%, and clinicians often get confused because of this. In fact, this is a total antibody to anti-HBc, which may exist for a long time. If its titer is low, it means that it has previously been infected with hepatitis B, which has epidemiological significance, and high titer has clinical diagnosis significance. For another example, in the determination of autoantibodies, a small number of normal people also have a small amount of autoantibodies, which is not only harmless to the body, but also helps the body to clear out aging and deteriorated cells. In addition, in clinical diagnosis, corresponding antibodies must be tested for different pathogenesis. For example, IgE should be detected in type I hypersensitivity reactions, while IgG and IgM antibodies should be measured in type II hypersensitivity reactions. Epstein-Barr virus shell membrane antigen-IgA (IgA / VCA antibody). In addition, antibody determination, like other tests, has the problem of false positives and false negatives, which may be caused by imperfect methodologies or due to differences in the body's reactivity. Be careful when interpreting the results.