Suppression of Primary Immunization by Carrageenan —A Macrophage Toxic Agent

Carrageenan, a sulfated polygalactose toxic for macrophages, was used in this study to examine the role of peritoneal macrophages in the primary immune response. Intraperitoneal (i.p.) injections of carrageenan led to complete suppression of anti-SRBC antibody formation only when antigen was injected i.p. Intravenous (i.v.) injections of antigen resulted in a normal immune response, suggesting that immunization was suppressed bytoxicity of carrageenan for peritoneal macrophages. Suppression of anti-SRBC antibody was also seen in animals treated by i.v. injections of carrageenan. Our results provide in vivo evidence that macrophages are required for a primary immune response.