Cell-mediated immunological responsiveness in mice decomplemented with cobra venom factor.

In vivo administration of cobra factor (CoF) the C3-activating protein of cobra venom, had no suppressive effect on the in vitro response of lymphocytes to PHA, LPS or allogeneic cells; nor did it affect the generation of cells cytotoxic to allogeneic target cells. HVG reactivity was inhibited by commercially available but not purified CoF, and the latter also failed to prolong skin allograft survival. It is concluded that in vivo complement depletion does not interfere with T cell responses, and that previous reports of prolonged survival of skin allografts and inhibition of cutaneous delayed hypersensitivity reactions following treatment with CoF may have been due to impurities in the preparations used.