TRICHOSANTHIN, AN INITIATOR OF THE ALTERNATIVE COMPLEMENT ACTIVATION PATHWAY

Trichosanthin (TCS), a protein purified from the plant Trichosanthes K irilowii Maxim, activates normal human serum complement via the altern ative pathway, as shown by TCS-induced C3 conversion in normal serum a nd its prevention by depletion of factor B, but not with the addition of EGTA. Injection of TCS to BALB/c mice consumed the complement alter native pathway (APC) activity in serum, implying in vivo activation of the alternative pathway by TCS. Elevation of peripheral blood leucocy te count as well as protein exudation and neutrophil accumulation in t he peritoneal cavities could be induced by peritoneal injection of TCS . The main effect of complement activation by TCS was demonstrated to be induction of neutrophil accumulation.