<prompt> In graft rejection, type of HLA involved is?MHC Class IIMHC class IMHC Class IIIMHC Class IV  <response>: In transplantation immunology, the major impact in graft loss comes from the effects of HLA-B and HLA-DR antigensThe histocompatibility antigens human leukocyte antigens - HLA are cell surface antigens that induce a response leading to rejection of allograftsThe principal physiologic function of the cell surface histocompatibility molecules is the bound peptide fragments foreign proteins for presentation to antigen-specific T cells.The histocompatibility antigens are encoded by a closely linked multiallelic cluster of genes: Mix histocompatibility complex MHC or Human leukocyte antigens complex HLA complexHLA complex of genes is located on the short arm of chromosome 6.It consists of three separate clusters of genes:HLA Complex MHC complex 