Triggering of cultured neoplastic mast cells by antibodies to the receptor for IgE.
Cell surface receptors for IgE were isolated from detergent lysates of iodinated, IgE-saturated, rat basophilic leukemia cells by precipitation with anti-IgE antibodies followed by chromatography at acid pH. The isolated material showed a single 125I-band (m.w. approximately 58,000) on gel electrophoresis in sodium dodecyl sulfate and was used to immunize a rabbit. The resulting anti-serum was reacted with lysates of surface iodinated mouse or rat tumor mast cells. Analysis of the precipitates on (10%) gel electrophoresis revealed one major peak comprising greater than 80% of the detectable counts and having an estimated m.w. of approximately 58,000. The antiserum reacted with detergent-solubilized and cell-bound receptors in the presence or absence of excess IgE; it also inhibited the binding of 125I-IgE. Cultured mouse mastocytoma cells never exposed to IgE released 3H-serotonin when incubated with F(ab')2, but not Fab' fragments of the antiserum, which had been rigorously freed of IgE and anti-IgE. The release was inhibited in the presence of excess IgE, was Ca++ dependent, and equaled 80% of the maximum obtained with IgE and anti-IgE. We conclude that aggregation of the receptors for IgE provides the critical signals for cell activation.
D000818:Animals; D000888:Antibodies, Anti-Idiotypic; D000912:Antibodies, Neoplasm; D001666:Binding Sites, Antibody; D001667:Binding, Competitive; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D004306:Dose-Response Relationship, Immunologic; D004591:Electrophoresis, Polyacrylamide Gel; D007073:Immunoglobulin E; D007457:Iodine Radioisotopes; D008407:Mast Cells / Q000276:immunology*; D051379:Mice; D009374:Neoplasms, Experimental / Q000276:immunology*; D011817:Rabbits; D051381:Rats
D000888:Antibodies, Anti-Idiotypic; D000912:Antibodies, Neoplasm; D007457:Iodine Radioisotopes; D007073:Immunoglobulin E