CPH-86, a highly purified podophyllotoxin, efficiently suppresses in vivo and in vitro immune responses.

Podophyllotoxin, a component of the plant resin Podophyllin, has been used as a clinical drug for many years. Recently it has been highly purified under the denomination of CPH-86. We here demonstrate that extremely low doses of the compound efficiently inhibit antibody responses to SRBC and prolong allogeneic skin graft survival in mice. In vitro immune reactions, such as mitogen and alloantigen induced proliferation and development of cytotoxic T cells, are also suppressed in a dose dependent manner. This effect does not seem to be due to direct cellular toxicity or to a shift in the kinetic pattern of the responses.