Fc receptors for IgE on mouse macrophages and macrophage-like cell lines.

Murine alveolar and peritoneal macrophages (AM phi, PM phi) and M phi-like cultured cell lines were analyzed for IgE Fc receptors by rosette formation with mouse IgE-sensitized red cells and by binding of radiolabeled mouse IgE. A mean of 90.4% AM phi, 56.9% PM phi, 93.4% P388D1, 81.2% J774.1, 15.6% WEHI3, 54.7% WR19M.1, 52.3% RAW264.7, and 19.5% RAW309Cr.1 M phi-like cells formed IgE rosettes. The rosettes were specific for native mouse IgE and were inhibited by mouse IgE but not mouse IgG, IgA, IgM, or heat-denatured mouse IgE. Rat IgE, but not human IgE, induced rosettes and inhibited mouse IgE rosettes. Trypsin treatment of the M phi abolished IgE rosette formation. Mouse IgE bound to P388D1 M phi-like cells with a KA of 7.6 +/- 0.2 X 10(6) M-1 to 3.3 +/- 0.9 X 10(5) binding sites. After 30 min of incubation at 37 degrees C, 30 to 45% of AM phi, P388D1, and J774.1 M phi-like cells ingested erythrocytes sensitized with IgE but not unsensitized erythrocytes. The data indicate that mouse M phi bear Fc receptors specific for IgE that mediate phagocytosis of IgE-sensitized erythrocytes.