Fc gamma R-mediated endocytosis and expression of cell surface Fc gamma RIIb1 and Fc gamma RIIb2 by mouse bone marrow culture-derived progenitor mast cells.

摘要: Mouse IL-3-dependent, bone marrow culture-derived mast cells (BMMC) bind IgG immune complexes through Fc receptors for (Fc gamma R) but express minimal RIII on their surfaces. BMMC do not degranulate appreciably when R are perturbed with the rat anti-mouse RII/III mAb 2.4G2 and F(ab')2 mouse anti-rat (MAR). In contrast, after were cross-linked Na125I-labeled MAR at 37 degrees C, rapidly internalized complex. To identify species expressed surface of therefore implicated in endocytic response, two rabbit antipeptide antisera raised, one against a sequence common to cytoplasmic regions RIIb1 RIIb2 other unique region RIIb1. When immunoprecipitated from detergent extracts BMMC, digested N-glycosidase F, subjected SDS-PAGE, immunoblotted RIIb1- RIIb1/b2-specific antibodies, found RIIb2. Selective immunoprecipitation plasma membrane-localized [3H]leucine-labeled showed that ratio cell was similar initial biosynthetic ratio. Thus, contrast mature serosal binding complexes, immature cells, which prototype, may have role clearance without concomitant release proinflammatory mediators.