U V Irradiation Can Induce In Vitro Clonal Anergy in Alloreactive Cytotoxic

The alloreactive cytotoxic T lymphocytes (CTL) were generated by coculturing peripheral blood mononuclear cells (PBMC) with allogeneic Sa cells (an Epstein-Barr virus [EBVI-transformed B-cell line). The CTL did not proliferate in response to UV-B-irradiated Sa cells unless exogenous interleukin-2 (IL-2) was present, although they could kill the UV-B-irradiated Sa cells. The results indicate that UVB-irradiated Sa cells do not provide sufficient signals for the proliferation of the CTL while they can be recognized by CTL and induce high-affinity IL-2 receptor (IL-2R) expression on them. The alloreactive CTLcould be rendered anergic by previous exposure to UV-6-irradiated Sa cells. The alloreactive CTL previously stimulated with UV-B-irradiated Sa cells failed to proliferate in response to nontreated Sa cells. proliferation of the anergic CTL could not be restored by Sa cells and exogenous IL-2 but by the com-