Lack of Ir-gene control in T-cell responses restricted by allogeneic MHC molecules

T cells were depleted of alloreactive cells by 5-bromo-2-deoxyuridine (BUdR) and light treatment, and were subsequently primed in vitro using allogeneic antigen presenting cells (APC) and antigens, the response to which is under immune response (Ir)-gene control. Antigen-specific secondary proliferative responses restricted by allogeneic Ia molecules of the APC were obtained in all strain combinations tested, irrespective of the Ir phenotype of either the T cell or the APC. Thus the data establish that the response of T cells to antigen presented by allogeneic APC is not under Ir-gene control. The implications of this finding to the mechanism of Ir-gene controlled non-responsiveness, and its impact on current views of the T-cell repertoire are discussed.