Antigen-presenting cells present antigens in the form of peptides on histocompatibility molecules. Two major types of alloantigens are blood group antigens and histocompatibility antigens. Major histocompatibility antigen testing may be performed to investigate genetic susceptibility to uveitis. HLA is a major histocompatibility complex (MHC) antigen specific to humans. Compounds derived from the major histocompatibility complex (MHC) are bound to several urinary proteins. Most T cell receptors bind to the major histocompatibility complex on cells of the body. Body odor is largely influenced by major histocompatibility complex (MHC) molecules. They cause problems of rejection less frequently than those of the major histocompatibility complex (MHC). The recipient developed GVHD despite having a HLA- matched genes at the Major Histocompatibility locus.