Affinity and inhibitory capacity of T-cell proliferation of monoclonal anti-Ia antibodies.

The rates of dissociation from the surface of Ia-positive spleen cells of three different anti-Ia monoclonal antibodies were evaluated and compared with their inhibitory effects on T-lymphocyte proliferative responses involving the same spleen cell population, either as a source of accessory cells (responses to soluble antigens) or as allogeneic stimulating cells. In general, a direct relationship was observed between the affinity with which these monoclonal antibodies interact with Ia-positive cells and the magnitude of their inhibitory effects, whether soluble antigen- or alloantigen-induced responses were tested. These results indicate that the affinity of monoclonal antibodies is a factor that has to be considered to the same extent as their fine specificity when interpreting the results of inhibitory studies of T-cell responses by anti-Ia monoclonal antibodies.