A histopathological study of the effects of intravenously administered lambda carrageenan in the mouse, with particular reference to the macrophage system.

Intravenously administered lambda-carrageenan rapidly precipitates in the marginal zone of the spleen, the hepatic sinuses and the capillaries of the heart, lung, kidney and adrenal gland. Extensive coagulative necrosis of the liver and myocardium is seen at 24 h. Phagocytosis occurs at 3 days, and is associated with transformation of the lymphocytes of the splenic white pulp. Circulating carrageenan-containing macrophages adhere to vascular endothelium in the lung and at 6 days are situated beneath it. At 30 days carrageenan granulomas have formed in the spleen and liver, probably as a result of macrophage recirculation.