How many HLA alleles are there?
Not too many people know that HLA stands for the human leukocyte antigen system. The main idea is that HLA is the name of the loci of genes that encode for major histocompatibility complex(MHC) in humans. There are three types of HLA alleles: class I HLA (HLA-A, HLA-B, HLA-C) and 3 major types of class II HLA (HLA-DP, HLA-DQ and HLA-DR). Needless to say, there are HLAs corresponding to MHC class I (A, B, and C), HLAs corresponding to MHC class II and HLAs corresponding to MHC class III. Keep in mind that the major HLA antigens are essential elements for immune function.