Cross-reactivity patterns of murine cytotoxic T lymphocytes.

Cross-reactivity of TNP-immune, virus-immune, and alloreactive murine cytotoxic thymus-derived (T_c) cells was investigated at the level of target cell lysis. Alloreactive T_c cells cross-reacted on TNP-modified and unmodified third-party targets and on syngeneic TNP-modified targets but did not cross-react on syngeneic virus-infected targets. TNP-immune T_c cells showed marked cross-reactivity on certain allogeneic targets modified by TNP (loss of H-2 restriction) and also on certain unmodified allogeneic targets but did not cross-lyse virus-infected syngeneic targets. Targets treated with TNP-Sendai virus were not lysed by TNP-immune T_c cells, but T_c cells stimulated by cells treated with TNP-Sendai virus lysed such targets readily. These results are consistent with the view that T_c-cell recognition of foreign H-2 antigens and TNP-modified self-H-2 antigens are mechanistically similar (possibly via one receptor), whereas recognition of viral plus H-2 antigens is different (possibly via two receptors).Virus-immune T_c cells ubiquitously exhibited strong cross-reactivity on syngeneic TNP-modified targets using pox-, arena-, alpha-, myxo-, and paramyxoviruses for T_c-cell induction. The lysis of virus-infected targets by virus-immune T_c cells could be inhibited by cold TNP-modified competitors, thus establishing that some individual virus-immune T_c cells could recognize both types of target cells. This genuine cross-reactivity at the effector level was not observed at the level of induction of secondary responses, since the cross-reactive subset of virus-immune memory T_c cells could not be activated by TNP-modified stimulator cells but could be activated by virus-infected stimulators. These results implied that requirements for stimulation of precursor T_c cells are sometimes different from antigenic requirements for recognition and lysis of effector T_c cells.