Endocytosis of Agarose in Mouse Peritoneal Macrophages in Vitro

Abstract

Endocytosis of 3H-labeled and non-radioactive agarose was studied in mouse macrophages in vitro. Endocytosis was greatest and most rapid in syngeneic mouse serum and in human serum, reaching a plateau after 12 h of incubation. Serum (10%) was the minimum concentration giving optimal ingestion. Endocytosis appeared to be regulated by mechanisms involving complement factors C3 and B. Different pretreatments of sera, inactivating or depleting C3 and B, resulted in 70-80% reduction of endocytosis. Preincubation of agarose in untreated serum increased the endocytosis of agarose in heat-inactivated serum 3-fold, indicating that the essential factors were bound to agarose. Antibodies against C3 and B reduced endocytosis moderately but significantly.