Affiliation:
1. From the Johns Hopkins Asthma and Allergy Center, Baltimore, MD; and Tanox Biosystems, Inc, Houston, TX.
Abstract
In vivo studies suggested the possibility of an IgE-dependent regulation of high-affinity (FcRI) IgE receptor expression on basophils. The current studies extend these observations to in vitro cultures of human basophils. Incubation of basophils for 3 to 4 weeks resulted in a slow dissociation of IgE antibody, during which time FcRI expression decreased, as measured by flow cytometry using the anti-FcRIα monoclonal antibody, 22E7, or by measuring FcRIα mass by Western blotting of whole-cell lysates. Culture of basophils with IgE resulted in upregulation of FcRIα expression by both flow cytometry and Western blotting of whole-cell lysates. Upregulation followed a linear time course during 2 weeks of culture. The relative increase in FcRIα density depended on the starting density; with starting densities of FcRIα of 10,000 to 170,000 per basophil, the upregulation varied 20- to 1.1-fold, respectively. Upregulation occurred in high-purity basophils, was not influenced by IgG at concentrations up to 1 mg/mL, and was inhibited by dimeric IgE. Heat-inactivated IgE was less effective and the monoclonal antibody CGP51901 that prevents IgE binding to FcRIα blocked the ability of IgE to induce upregulation. The dose-response curve for IgE-induced upregulation had an effective concentration50 of 230 ng/mL. Although the receptor through which IgE induces this upregulation is not yet known, several characteristics suggest that the upregulation is mediated by IgE interacting through FcRIα itself.
Publisher
American Society of Hematology
Subject
Cell Biology,Hematology,Immunology,Biochemistry
Cited by
118 articles.
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