Cyclosporin A abrogates proliferation of T cells and generation of suppressor and cytotoxic T-cell function induced by Epstein-Barr virus.

Cyclosporin A (CYA) promotes the outgrowth in vitro of Epstein-Barr-virus(EBV)-infected cells of immune donors. In the present study, the effects of CYA on the T-cell responses developed to an in-vitro EBV infection were studied. Cyclosporin A, by acting on the responder cells and not on stimulator cells, strongly inhibited the proliferation of T cells normally induced by EBV-infected autologous cells. Moreover, T cells from cultures not exposed to CYA exerted suppression on both alloantigen-induced DNA synthesis and PWM-stimulated immunoglobulin producton of autologous peripheral blood mononuclear cells. In contrast, T cells from cultures treated with CYA exhibited significantly less or no suppressor activity as determined in both indicator system. Finally, CYA abrogated the generation of cytotoxic T cells against EBV-infected autologous cells, whereas non-CYA -treated T cells killed the virus-transformed target cells. Both suppressor and cytotoxic T-cell functions are known to play an essential role in the control of EBV infection by limiting the continuous growth of the virus-infected cells. These results, therefore, stongly suggest that cyclosporin A promotes the outgrowth of EBV-infected cells by abrogating the T-cell responses to the Epstein-Barr virus.