Glucocorticoids inhibit IgE receptor expression on the human monocyte cell line U937.
Cells of a human monocyte-like cell line (U937) were analysed for IgE Fc receptors (Fc epsilon R) before and after glucocorticoid treatment. Specific binding of human myeloma IgE (Sha) was measured by 125I-labelled IgE, and by fluorescein-labelled IgE monitored by flow cytometry. Treatment of cells with dexamethasone or other steroids with glucocorticoid activity caused a significant decrease in Fc epsilon R expression. The inhibition was dose dependent, with a half-maximal effect at 20 nM dexamethasone, a concentration which is near to the dissociation constant of glucocorticoid receptors for dexamethasone. Inhibition of Fc epsilon R was significant beginning 8 h following glucocorticoid treatment and reached a plateau at 24 hr. The Ka for IgE binding was similar for control and dexamethasone-treated cells, while the number of IgE binding sites was decreased by 50-60%. Culture supernatants from dexamethasone-treated U937 cells which were concentrated 10-fold and depleted of free steroid did not affect Fc epsilon R expression. These results demonstrate that glucocorticoids can directly decrease the number of Fc epsilon R. This effect could participate in the glucocorticoid-induced suppression of IgE-mediated allergic reactions.
Náray-Fejes-Tóth
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A
Cornwell
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GG
Guyre
P M
PM
D000911:Antibodies, Monoclonal / Q000276:immunology; D000954:Antigens, Surface / Q000276:immunology; D001666:Binding Sites, Antibody; D002460:Cell Line; D003907:Dexamethasone / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D007073:Immunoglobulin E; D009000:Monocytes / Q000276:immunology; D011961:Receptors, Fc / Q000187:drug effects*; D017455:Receptors, IgE; D011971:Receptors, Immunologic / Q000187:drug effects*; D013997:Time Factors
D000911:Antibodies, Monoclonal; D000954:Antigens, Surface; D011961:Receptors, Fc; D017455:Receptors, IgE; D011971:Receptors, Immunologic; D007073:Immunoglobulin E; D003907:Dexamethasone