Binding of monoclonal antibodies inhibits dissociation but not exchange of HLA and beta 2-microglobulin.
Hyafil and Strominger (Proc Nat Acad Sci USA 76:5834, 1979) showed that the complex of papain-solubilized HLA heavy chain and beta 2-microglobulin (beta 2-m) will measurably dissociate and exchange with free beta 2-m at 37 degrees C but not at 4 degrees C. We have investigated the affects of monoclonal antibodies on these processes. The dissociation reaction at 37 degrees C is inhibited by the presence of HLA-A,B,C specific monoclonal antibodies. Monomorphic antibodies such as BB7.7 against combinatorial determinants are most potent though antibodies against many different determinants of the HLA heavy chain are effective. This suggests that dissociation of beta 2-m from HLA involves a conformational change of the HLA heavy chain which is prevented by antibody binding. BB7.7 also increased the rate of association of HLA heavy chain and beta 2-m. This affect was significantly greater at 37 degrees C and 25 degrees C than at 4 degrees C. Monoclonal antibodies that inhibited dissociation did not inhibit the beta 2-m exchange reaction. If beta 2-m exchange proceeds through a simple dissociation/association reaction then the affect of antibody inhibition on dissociation is almost exactly compensated by its enhancement of association. Alternatively B 2-m exchange may not proceed via a simple dissociation/association reaction.
D000911:Antibodies, Monoclonal / Q000276:immunology*; D001665:Binding Sites; D006680:HLA Antigens / Q000276:immunology*; D006801:Humans; D066298:In Vitro Techniques; D008968:Molecular Conformation; D008970:Molecular Weight; D001613:beta 2-Microglobulin / Q000276:immunology*
D000911:Antibodies, Monoclonal; D006680:HLA Antigens; D001613:beta 2-Microglobulin