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

Abstract

We have isolated cloned variants in phagocytosis from a cloned continuous murine macrophage-like cell line, J774.2. A selection procedure against Fc receptor-mediated phagocytosis was devised using IgG-coated SRBC containing a toxic drug, tuberc,.‘din, as the lethal agent. A series of variant clones deficient in Fc receptor-mediated phagocytosis were isolated. Such variants occurred at low frequency (-6 × 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 Br-cAMP, in others, the drug was without effect. It is likely, therefore, that different variants are defective in several distinct steps critical to Fc receptormediated phagocytosis. © American Society for Clinical Pathology.