Differential cyclophosphamide sensitivity of precursor cells in allogeneic and H-2 restricted cytotoxic responses.

Spleen cells from cyclophosphamide-treated mice responded in vitro to allogeneic stimulator cells but not to TNP-coupled syngeneic spleen cells. Similarly, cells from female mice, primed in vivo with syngeneic male cells, could not respond in vitro to male spleen cell stimulation if the mice were pretreated with cyclophosphamide. These results suggest that the precursor cells for H-2-restricted cytotoxic responses belong to a different T-cell subpopulation than the precursor cells for allogeneic responses.