MHC typing:

• MHC class 1, three loci on short arm of chrom 6

• B, C, A. There are hundreds of alleles at each locus, many are conserved within racial populations

• Present on all nucleated cells

•  Important in graft rejection

• MHC class 2, also on chrom 6

• DP, DQ, DR

• Important in GVHD

• On  B –cells, monocytes, dendritic cells, some epith cells

• On Activated T-cells