The history of the test is to determine tissue compatibility when scientists observed leukocyte agglutinating antibodies in the serum of patients exposed to alloantigens through transfusion or pregnancy. HLA antigens are classified according to structural and functional similarities to Classes one and two. HLA-A, B, C and HLA Class A HLA-A, HLA-DR, DQ , DP, DM, DO have been identified and studied. There are also over 1800 polymorphisms.
Class A of HLA molecules (A, B, C) exist at the level of most nucleated cells and platelets, and class II molecules (DR, DP, DQ) at the level of B cells, antigen presenting cells such as cells Dendritic, abnormal, and endothelial cells are observed and play an important role in the immune system for the detection of non-insider self-esteem.
HLA genes appear to be the same in each person, in other words, each person shows two alleles from several HLA polymorphic alleles inherited from the parent on the surface of their cells. In this way, there is very little chance that two people who are not brothers and sisters have the same HLA. HLA antigens act as an indicator for the self-identification of the immune system, and the hemorrhage in the HLA transcription acts as a stimulant for the immune response.
The HLA system is used as an epidemiologic marker for DNA fingerprinting (identity and abstinence), binding and receptor compatibility, to reduce the likelihood of GVHD release, for converting platelet transfusion in resistant patients.
Methods for determining HLA
Identification of HLA Class I Antigens (HLA Class I)
The first method used to determine the HLA polymorphism was complementary lymphocytotoxicity developed by Terasaki and Mc Clelland. In this serologically tested test, anti-HLA antibodies containing adherent anti-HLA antibodies are adjacent to peripheral blood lymphocytes and after incubation, the serum of rabbits is added and re-incubated.
Identification of HLA Class II Antigens (HLA Class II)
In these cases, since the HLA-DR is on the lymphocytes of B, they should separate the lymphocytes B and T. Additionally, B-type antisera should also be used for platelets to absorb HLA-A, B, C anti-sera. The basics of testing are like HLA-A, B, C, and only incubation times are longer. It should be noted that the efficacy of the above method (serologic method) is not acceptable for class II antigens, and a leukocyte culture experiment (MLC) can be used for HLA-DR.
Mixed Lymphocyte Culture, (MLC)
In this study, the association of class II antigens and, more precisely, the similarity or differences between the HLA-DR, DQ, and DP antigens are investigated by two-person lymphocytes. In this study, if the lymphocytes of two individuals adjacent to the class II antigens are different, each lymphocyte is stimulated and enhanced by other lymphocytes.
The degree of proliferation of lymphocytes can be measured by the ability of these cells to absorb radioactive timemidine in DNA. The advantage of this method in comparison with microcytotoxicity is that it exhibits a better texture than TH-type activity in response to class II MHC antigens. And the disadvantages of this are the length of the test.
- This test should be carried out immediately after sampling.
- If the sampling is done outside the laboratory, after sampling, the sample is sent immediately to the laboratory.
- For serological testing of the sample at room temperature and for molecular testing, the sample should be stored in the refrigerator.