INHIBITION OF COMPLEMENT BY CARRAGEENIN: MODE OF ACTION, EFFECT ON ALLERGIC REACTIONS AND ON COMPLEMENT OF VARIOUS SPECIES.

Carrageenin prevents the reaction of guinea-pig C′ with sensitized red blood cells, probably by a direct inactivation of the C′1. The anti-complementary effect of carrageenin is antagonized by protamine sulphate. Marked reduction of circulating C′ activity in guinea-pigs resulting from intravenous injection of carrageenin, does not alter their susceptibility to acute or protracted anaphylactic shock. The C′ activities of human, guinea-pig, rabbit, rat and monkey sera are all inhibited in vitro by carrageenin.