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HLA region of Chromosome 6. The human leukocyte antigen (HLA) system is a complex of genes on chromosome 6 in humans that encode cell-surface proteins responsible for regulation of the immune system. [1] The HLA system is also known as the human version of the major histocompatibility complex (MHC) found in many animals. [2]
Unlike hemolytic disease of the fetus and newborn, NAIT occurs during the first pregnancy in up to 50% of cases, [1] and the affected fetuses may develop severe thrombocytopenia (<50,000 μL −1) very early during pregnancy (as early as 20 weeks gestation, consistent with the development of platelet antigens, [1] and the majority of the time ...
Hyperacute rejection occurs when, before the transplantation, the recipient has preformed anti-HLA antibodies, perhaps by previous blood transfusions (donor tissue that includes lymphocytes expressing HLA molecules), by anti-HLA generated during pregnancy (directed at the father's HLA displayed by the fetus), or by previous transplantation;
Donor-specific antibodies (DSA) are a concept in transplantation medicine and describe the presence of antibodies specific to the Donor's HLA-Molecules. These antibodies can cause antibody-mediated rejection and are therefore considered a contraindication against transplantation in most cases. [ 1 ]
In any pregnancy, the maternal KIR genotype could be AA (no activating KIRs), AB, or BB (1–10 activating KIRs) and the HLA-C ligands for KIRs are divided into two groups: HLA-C1 and HLA-C2. Studies have shown that there is a bad compatibility between specifically maternal KIR AA and fetal HLA-C2 which leads to recurrent miscarriage ...
An HLA allele coding non-expressed gene is termed "Null Allele", for example: HLA-B*15:01:01:02N. The expression level can also detected by serotyping, an HLA gene coding for antigens which has low protein expression on the cell surface is termed "Low Expresser", for example: HLA-A*02:01:01:02L.
Blood compatibility testing is routinely performed before a blood transfusion.The full compatibility testing process involves ABO and RhD (Rh factor) typing; screening for antibodies against other blood group systems; and crossmatching, which involves testing the recipient's blood plasma against the donor's red blood cells as a final check for incompatibility.
A panel-reactive antibody (PRA) is a group of antibodies in a test serum that are reactive against any of several known specific antigens in a panel of test leukocytes or purified HLA antigens from cells. It is an immunologic metric routinely performed by clinical laboratories on the blood of people awaiting organ transplantation. [1]