Suppressor cells for in vivo cytotoxic responses--regulation of the in vivo activation of cytotoxic T-lymphocytes by suppressive cells.

A significant in vivo activation of cytotoxic T-lymphocytes (CTL) against trinitrophenyl (TNP)-modified autologous cells and of a DNA-synthesis response in the peripheral lymphnodes is observed in cyclophosphamide (CyP) treated mice after skinpainting with trinitrochlorbenzene (TNCB) or after injection of TNP-coupled spleen cells (TNP-Spl) into the footpads. The activation of these responses can be suppressed by the transfer of spleen cells or lymphnode cells from skinpainted normal mice, but not from skinpainted mice that had been pretreated with CyP. Suppressive activity is also induced by injections of TNP-Spl i.p. or trinitrobenzosulfonate (TNBS) i.v. Optimal activation of suppression occurs with 3--4 days. The suppressive activity is antigen-specific at least in respect to its activation. Suppressor cells of this kind also suppress the induction of delayed hypersensitivity (DH) responses and the priming for in vitro secondary responses. However, these two responses are less sensitive to the suppression, and their in vivo activation is accordingly much less restricted with the in vivo activation of DNA-synthesis and primary CTL responses. DH and CMC memory can be activated ty TNCB skinpainting without pretreatment with CyP.