Activation of the alternative pathway of bovine complement by Trypanosoma congolense

Homogenates of Trypanosoma congolense and particulate and supernatant fractions thereof were, by two different techniques, shown to activate bovine complement via the alternative pathway. (1) All three preparations converted complement factor Bbov to its split product B gamma 2 as demonstrated (a) qualitatively by immunoelectrophoresis and (b) quantitatively by radial immunodiffusion. (2) Lysis of guinea-pig erythrocytes by bovine complement via the alternative pathway was inhibited by whole homogenates and particulate fractions of T. congolense organisms.