Rhesus and African green monkey leukocyte response to steroids, antithymocyte globulin, and 60Co treatments.

Rhesus and African green monkeys were treated with dexamethasome, antithymocyte globulin, 60Co irradiation, or combinations of those immunosuppressive agents, and the leukocyte response was followed. The lymphocyte population could be significantly depressed with 60Co, but dexamethasone was required to maintain a low lymphocyte count. The ability of the immunosuppressed animals to support the growth of transplanted tumor cells was markedly enhanced by the addition of ATG to the treatment schedule, even though ATG had no effect on the numbers of leukocytes in the peripheral circulation.