Inhibition of T cell developmemt in thymic organ culture: Implications for the mechanism of action of cyclosporin A

Abstract

We have examined the effects of the immunosuppressive drug cyclosporin A (CsA) on the phenotypic maturation of T cells in thymic organ cultures begun at day 16 of gestation. CsA specifically inhibited the generation of cells expressing high levels of α/β TcR/CD3 complexes and a mature phenotype defined by CD4 and CD8 surface markers. Adding interleukin (IL) 1β, IL 2 or IL 4 failed to reverse the effects of CsA, and major histocompatibility complex class II expression in the thymic medulla was preserved. Possible mechanisms of CsA‐mediated inhibition of T cell development are discussed.