Effect of Cyclosporin A on the Generation of Cytotoxic T Lymphocytes in Mouse Mixed Lymphocyte Culture

Abstract

Cyclosporin A inhibited at equal concentrations both the proliferative response and cytotoxic T lymphocyte generation in 1-way mouse spleen cell mixed lymphocyte culture. The 50% inhibitory concentration was in all experiments 10-2-10-1 .mu.g/ml. The inhibition was directly proportional to how early the drug was added to the culture: a complete inhibition of both responses was obtained if the drug was added on day 3, and a partial inhibition if added on day 4 of culture. Cytological analysis of the culture cells demonstrated that resting lymphocytes were not damaged at 100-1000-fold concentrations of the drug giving complete blastogenic response inhibition. Apparently, cyclosporin A is most effective if present throughout the induction phase of the immune response.