Studies on the activity of antithymocyte serum (ATS), particularly on the relation between its anti-inflammatory and immunosuppressive effects.

Anti-inflammatory and immunosuppressive activity of equine antirabbit antithymocyte serum (ATS) was studied. ATS lowered serum levels of complement, inhibited cell proliferation in the granulation test, and prolonged survival of allogeneic skin grafts. Its action was accompanied by lymphopenia. Repeated immunization enhanced the activity of ATS in the graft rejection test and the drop in serum complement, and at the same time attenuated the effect on the granulation process and lowered proteolytic activity.