The role of three distinct Ia-like antigen molecules in human T cell proliferative responses: effect of monoclonal anti-Ia-like antibodies.

Murine monoclonal antibodies (MoAb) to three distinct Ia-like molecules were studied for their inhibitory effects on antigen- and alloantigen-induced T cell proliferations. The MoAb were classified into three groups according to the molecules they recognized. Both the group I MoAb reacting with DR molecules and the group III MoAb were capable of inhibiting T cell proliferative responses to PPD- and HSV-Ag-pulsed APC, autologous B-LCL, and alloantigens. On th other hand, the group II MoAb, which reacted with a determinant on the molecule carrying MB1 determinants, was only capable of inhibiting T cell responses to alloantigens. These results suggest that the structure of the molecules correlates with the functional repertoire of the human Ia-like antigens.