Failure of T cells specific for strong histocompatibility antigens to cooperate with B cells for a humoral response.

Thymus-derived lymphocytes (T cells) selected for reactivity to strong histocompatibility antigens over a period of one to twelve months in vitro were tested for their ability to cooperate with bone marrow-derived lymphocytes (B cells) for a humoral response. If cultured with normal syngeneic or allogeneic spleen cells and sheep erythrocytes (SRBC) as immunogen, inhibition of the anti-SRBC response was observed. Similarly, in T cell-free spleen cells the alloreactive T cells did not stimulate a humoral response, indicating that they cannot exert cooperative activity on B cells. Since it was possible that the alloreactive T cells may cooperate with B cells in a humoral response to immunogens carrying histocompatibility antigens, hapten-coupled tumor cells were also used as immunogen. Though it is demonstrated that the alloreactive T cells do recognize the tumor cell immunogen, no stimulation of the B cells for a humoral response against the tumor cell is observed. This result, as well as the finding that the antigenic requirements for T helper cell priming and cell proliferation of the alloreactive T cells are different, suggests that these alloreactive T cells and helper T cells belong to different T cell subsets.