Effect of cyclosporin a on normal, mitogen-stimulated and Marek's disease virus-exposed and transformed chicken lymphoid cells.

Studies have been made with the immunosuppressive drug cyclosporin A (CsA) to examine its value in the establishment of lymphoid tumour cell lines from Marek's disease (MD) lymphomas and from lymphoid cell cultures exposed to MD virus in vitro. CsA was shown to depress the proliferative response of normal spleen cells to phytohaemagglutinin, Concanavalin A and pokeweed mitogen, and to a lesser extent to lipopolysaccharide. Short-term proliferative responses of lymphoma cells were either not affected, depressed or stimulated by CsA. The efficiency of establishment of lymphoid cell lines from long-term cultures of lymphoma cells was not increased by CsA, and the drug had a depressive effect on the proliferation of cell lines in the lympho-cytoid stage. The majority of lymphoblastoid cell lines studied were stimulated by CsA. Interleukin 2 partially overcame the suppressive effect of CsA on the cell lines, and enhanced the stimulatory effects. Cultures of lymphoid cells exposed to MD virus in vitro were usually depressed by CsA; a few stimulatory combinations were observed, but these were not considered to be of biological significance. These results indicate that CsA suppresses normal T-cell responses in the chicken, but that some MD-associated lymphoid cells are stimulated by the drug, in some instances at least by a direct effect.