Human HLA gene segment isolated by hybridization with mouse H-2 cDNA probes

The products of the highly polymorphic genes known as the major histocompatibility complex (MHC) have been shown to play a major part in the control of several aspects of the immune response and of susceptibility to certain diseases^1,2. The major transplantation antigens are membrane proteins composed of two noncovalently associated polypeptide chains: a light, non-polymorphic chain of molecular weight 12,000 (MW), called β₂-microglobulin, and a polymorphic, glycosylated heavy chain of ∼45,000 MW. The heavy chains in man and mouse are encoded in at least three loci of the MHC named HLA-A, -B and -C, and H-2D, K and L respectively. The available amino acid sequence data indicate extensive homology between human and mouse heavy chains^3,4. We therefore used a recently isolated cloned mouse H-2 cDNA probe⁵ to screen a human gene library. We have now characterized one of the recombinant phages obtained, λ HLA-12, and shown that it contains an authentic HLA sequence with evidence of a second one close by.