MAPPING OF THE MONOCLONAL-ANTIBODY W6 32 - SENSITIVITY TO THE AMINO-TERMINUS OF BETA(2)-MICROGLOBULIN/

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 hav e discovered that the reactivity of W6/32 is absolutely sensitive to t he amino terminus of human beta(2)-microglobulin (h beta(2)m). Bacteri ally expressed recombinant forms of h beta(2)m that have been extensiv ely used in structural and biochemical studies of MHC I molecules ofte n have an additional methionine at their amino terminus. Cell surface MHC I molecules reconstituted with allele-specific peptides and recomb inant h beta(2)m are reactive with Various HLA-specific mAbs, but not W6/32. In contrast, cell surface HLA molecules reconstituted with pept ide and native h beta(2)m, which has no amino terminal methionine, are recognized by W6/32 as well as other HLA-specific mAbs. Thus, the spe cificity of W6/32 includes the amino terminus of h beta(2)m.