Mapping of the monoclonal antibody W6/32: sensitivity to the amino terminus of β2‐microglobulin

Abstract

The monoclonal antibody W6/32 is one of the most commonly used pan-HLA-ABC antibodies in studying human MHC I structure and function. We have discovered that the reactivity of W6/32 is absolutely sensitive to the amino terminus of human beta2-microglobulin (hbeta2m). Bacterially expressed recombinant forms of hbeta2m that have been extensively used in structural and biochemical studies of MHC I molecules often have an additional methionine at their amino terminus. Cell surface MHC I molecules reconstituted with allele-specific peptides and recombinant hbeta2m are reactive with various HLA-specific mAbs, but not W6/32. In contrast, cell surface HLA molecules reconstituted with peptide and native hbeta2m, which has no amino terminal methionine, are recognized by W6/32 as well as other HLA-specific mAbs. Thus, the specificity of W6/32 includes the amino terminus of hbeta2m.