Properties of a murine monocytic tumor cell line J-774 in vitro. I. Morphology and endocytosis.

A murine monocytic tumor cell line J-774 was maintained in culture in the presence or absence of endotoxin, in an attempt to induce differentiation similar to that found in activated peritoneal macrophages. The morphology and Fc and C₃ receptor functions of attachment and ingestion were compared in the treated and untreated cultures. J-774 cells maintained in culture for 72 h seemed to resemble endotoxin-activated macrophages rather than normal peritoneal macrophages. A striking amount of ruffling was observed on the surface of the cells cultured for 3–4 days both in the presence and in the absence of endotoxin. As compared to the peritoneal macrophage where particles attached to the C₃ receptors are not ingested unless the cells are activated, J-744 cells attached and ingested particles via the C₃ receptor even without stimulation. The presence of endotoxin in the culture medium of these cells gave rise to more efficient phagocytosis but did not effect the temperature sensitivity of the phagocytic receptors. Both in treated and untreated cultures attachment to the Fc receptor was less dependent on the temperature than that of the C₃ receptor while ingestion was more sensitive in the Fc receptor as compared with the C₃ receptor.