The binding of antibodies to the solubilized and membrane-integrated mouse and rat receptor for IgE
Isersky, C.; Mendoza, G.R.; Metzger, H.
Journal of Immunology 119(1): 123-130
1977
ISSN/ISBN: 0022-1767 PMID: 406322 Document Number: 113400
Rabbit antiserum to rat basophilic leukemia . IgG, Fab' and Fab derived from this antiserum inhibited binding of 125I-IgE to whole rat and mouse tumor cells, normal rat peritoneal mast cells and to detergent-solubilized receptors from either cell line. The inhibition was less efficient with receptors from the mouse mastocytoma, and no inhibition of binding of 125I-IgE to normal mouse peritoneal mast cells was observed. The degree of inhibition of IgE binding to whole cells and solubilized rat and mouse receptors was inversely proportional to the time of incubation with and concentration of 125I-IgE. In a double immune precipitation system, anti-RBL reacted with detergent-solubilized receptors and IgE-receptor complexes derived from mouse or rat cells. Although nearly 100% of the free rat receptors could be precipitated, no more than 70% of free mouse receptors were maximally precipitated. The efficiency of precipitation of detergent-solubilized free receptors, and the maximal precipitation of receptor-IgE complexes by anti-RBL were decreased when the detergent was above the critical micelle concentration. Neither the precipitation of receptor-IgE complexes by anti-IgE, nor the binding of 125I-IgE to the free receptor was significantly affected under the same conditions. Anti-RBL probably contains antibodies to at least 2 discrete determinants on the receptor. One determinant (or group of determinants) is sufficiently close to the combining site for IgE to interfere with IgE binding and in turn is blocked from binding by the presence of IgE. The 2nd is distal from the 1st, is exposed at low detergent concentration even in the presence of IgE, but is blocked when the receptor interacts with larger amounts of detergent. The receptor is substantially embedded in the surface membrane.