Isolation of variants in phagocytosis of a macrophage-like continuous cell line.

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Abstract
Cloned variants in phagocytosis were isolated from a cloned continuous murine macrophage-like cell line, J774.2. A selection procedure against Fc receptor-mediated phagocytosis was devised using IgG[immunoglobulin G]-coated SRBC [sheep red blood cell] containing a toxic drug, tubercidin, as the lethal agent. A series of variant clones deficient in Fc receptor-mediated phagocytosis were isolated. Such variants occurred at low frequency (.apprx.6 .times. 10-5), were stable, and appeared to possess Fc receptors. The degree to which they were defective in phagocytosis of IgG-coated SRBC varied from clone to clone, yet all clones were able to phagocytize latex particles. The phagocytic defect in some variants could be corrected by the addition of 8-bromo cyclic AMP; in others, the drug was without effect. Different variants may be defective in several distinct steps critical to Fc receptor-mediated phagocytosis.