Abstract:

Major histocompatibility complex (MHC) is called 'Human Leukocyte Antigens (HLA)' in humans. This region consists of four main groups which are the MHC Class I (HLA-I, -B, -C, -E, -F, -G), MHC Class II (HLADR, -DP, -DQ, -DO, DN), MHC Class III (C2, C4A, C4B, PF,TNF-H,I) and, MHC Class IV (SK12W, Hsp70, AIF-I IC7 B144, LTB, TNF, LTA, IkBL, BATI, MICA, MICB) antigens. Class IV region has also been referred to "inflammatory region".HLA molecules present antigens to T lymphocytes and initiate a specific immune response. Class I HLA molecules present antigens to CD8+ cytotoxic T cells while Class II Molecules present to CD4+ hepler T cells. Class III HLA molecules are not involved in antigen presentation. Class III and IV HLA molecules are primarily important in inflammation an autoimmune diseases. HLA are the most polymorphic genes of the genome . The most important field of use is the histocompatibility examination in tissue and organ transplantation Lately, the most studied subject is the association of HLA antigens with diseases. Certain HLA types are more frequent in some diseases In this review, it is given the information about structural functional features of HLA molecules and their clinical usage. Also, here is to give brief overview of HLA polymorphism and association of HLA antigens with diseases

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