Effect of the new immunosuppressive agent, cyclosporin-A, on natural killer cell and antibody-dependent cell-mediated cytotoxic activity.

Athymic nude mouse homozygotes (nu/nu) and the heterozygote nu/nu+ were injected intraperitoneally with 2 mg of cyclosporin-A (CS-A) twice, 72 and 1 h prior to analysis. We have found that in vivo administration of CS-A results in a significant suppression of natural killer (NK) cell and antibody-dependent cell-mediated cytotoxic (ADCC) activity which probably play an important role in tumor and graft rejection. T cells were also suppressed, in contrast, B cells were found to be immunocompetent as determined by cell proliferation and antibody-forming capacity in response to mitogens and antigens. The identity of cells mediating NK cell and ADCC activity and its relationship to T lymphocytes are also discussed.