MHC1 is involved in?

Ans. is 'a' i.e., Tumor lysis * HLA complex consists of three separate clusters of genes :-1) Class I (MHC-I)# It comprising of A, B and C loci (i.e. HLA-A, HLA-B, HLA-C). It is found on the surface of all nucleated cells and platelets.# Important cells with MHC-I (HLA-I) on surface are B-cells, T-cells, macrophages/monocytes, neutrophils, langerhans cells, dendritic cells, platelets (thrombocytes), epithelial cells of thymus and hepatocytes. MHC class I present antigen to cytotoxic CD-8 T cells (MHC-I restricted).# MHC class I is responsible for graft rejection and cell mediated cytolysis of viral infected or tumor cells.2) Class II (MHC-II)# It comprises 'D' region (HLA-DR, HLA-DQ, HLADP). It is found only on the cells of immune system, i.e. T-cells, B-cells, langerhans cells, dendritic cells, and macrophages.# MHC-II recognizes exogenous antigen (extracellular microbes, soluble proteins) and present it to CD4 helper T cells (MHC-II restricted). MHC-II is responsible for graft versus host response and mixed leukocyte reaction.3) Class III (MHC-III)# It encodes for complement components C2 & C4, properdin factor B, Heat shock protein and Tumor necrosis factor-a and b (TNF-a and b). MHC-III is involved in susceptibility to autoimmune diseases like SLE.