Náray-Fejes-Tóth A, Cornwell G G, Guyre P M
Immunology. 1985 Oct;56(2):359-66.
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.
在糖皮质激素处理前后，对人单核细胞样细胞系（U937）的细胞进行了IgE Fc受体（FcεR）分析。通过125I标记的IgE测量人骨髓瘤IgE（Sha）的特异性结合，并通过流式细胞术监测的荧光素标记的IgE进行测量。用地塞米松或其他具有糖皮质激素活性的类固醇处理细胞会导致FcεR表达显著降低。这种抑制作用呈剂量依赖性，在20 nM地塞米松时达到半数最大效应，该浓度接近糖皮质激素受体与地塞米松的解离常数。糖皮质激素处理8小时后，FcεR的抑制作用开始显著，并在24小时达到平台期。对照细胞和地塞米松处理的细胞的IgE结合Ka相似，而IgE结合位点的数量减少了50 - 60%。地塞米松处理的U937细胞的培养上清液经10倍浓缩并去除游离类固醇后，不影响FcεR表达。这些结果表明，糖皮质激素可直接减少FcεR的数量。这种效应可能参与了糖皮质激素诱导的IgE介导的过敏反应的抑制。
