Kawabe T, Takami M, Hosoda M, Maeda Y, Sato S, Mayumi M, Mikawa H, Arai K, Yodoi J
Institute for Immunology, Faculty of Medicine, Kyoto University, Japan.
J Immunol. 1988 Aug 15;141(4):1376-82.
The regulation of human low affinity FcR for IgE (Fc epsilon R2/CD23) and the soluble Fc epsilon R2 [IgE binding factor (BF)] of monocyte (U937), T (ED), and B (JIJOYE) cell lines was examined by anti-Fc epsilon R2 mAb (H107, Mab176) and the cDNA probe for Fc epsilon R2. The effect of IL-4 and IFN-gamma on Fc epsilon R2 regulation was variable among these three cell lines. IL-4 and IFN-gamma enhanced the Fc epsilon R2 gene expression and the production of Fc epsilon R2 and IgE-BF on U937, whereas IL-4 and IFN-gamma had no significant effect on the Fc epsilon R2 expression on ED. On JIJOYE, IL-4 enhanced the Fc epsilon R2 and IgE-BF production on both protein and mRNA levels. In U937 and JIJOYE cells, there was a marked increase of Fc epsilon R2 mRNA after combined stimulation with IFN-gamma and IL-4. However, in JIJOYE cells, there was a dissociation between the surface expression of Fc epsilon R2 and Fc epsilon R2 mRNA treated with IFN-gamma plus IL-4. In these cells. IFN-gamma even down-regulated the IL-4-induced expression of surface Fc epsilon R2. Stimulation of JIJOYE cells with both IFN-gamma and IL-4 resulted in the increase of the IgE-BF in the supernatant, suggesting that IFN-gamma enhanced the release of IgE-BF from Fc epsilon R2. The results indicated that Fc epsilon R2 and IgE-BF expression is regulated by IFN-gamma at least on two different levels: on transcriptional levels and the levels of cleavage of the surface Fc epsilon R2 to release soluble Fc epsilon R2 (IgE-BF). Ligands binding to the Fc epsilon R2 such as IgE and anti-Fc epsilon R2 mAb enhanced the surface expression of Fc epsilon R2 on these Fc epsilon R2(+) cell lines. This was mainly due to the surface accumulation of the receptors on JIJOYE and U937. However, the stimulation of ED by H107 and anti-Fc epsilon R2 mAb significantly enhanced the mRNA expression, indicating that Fc epsilon R2 synthesis may also be up-regulated by the specific ligands in some cell types.
利用抗FcεR2单克隆抗体（H107、Mab176）和FcεR2的cDNA探针，检测了人IgE低亲和力Fc受体（FcεR2/CD23）以及单核细胞系（U937）、T细胞系（ED）和B细胞系（JIJOYE）的可溶性FcεR2[IgE结合因子（BF）]的调控情况。IL-4和IFN-γ对FcεR2调控的影响在这三种细胞系中各不相同。IL-4和IFN-γ增强了U937细胞上FcεR2基因的表达以及FcεR2和IgE-BF的产生，而IL-4和IFN-γ对ED细胞上FcεR2的表达没有显著影响。在JIJOYE细胞上，IL-4在蛋白质和mRNA水平上均增强了FcεR2和IgE-BF的产生。在U937和JIJOYE细胞中，IFN-γ和IL-4联合刺激后FcεR2 mRNA显著增加。然而，在JIJOYE细胞中，IFN-γ加IL-4处理后FcεR2的表面表达与FcεR2 mRNA之间存在解离。在这些细胞中，IFN-γ甚至下调了IL-4诱导的表面FcεR2的表达。用IFN-γ和IL-4刺激JIJOYE细胞导致上清液中IgE-BF增加，表明IFN-γ增强了IgE-BF从FcεR2的释放。结果表明，FcεR2和IgE-BF的表达至少在两个不同水平上受IFN-γ调控：转录水平以及表面FcεR2裂解以释放可溶性FcεR2（IgE-BF）的水平。与FcεR2结合的配体，如IgE和抗FcεR2单克隆抗体，增强了这些FcεR2（+）细胞系上FcεR2的表面表达。这主要是由于JIJOYE和U937细胞上受体的表面积累。然而，H107和抗FcεR2单克隆抗体对ED细胞的刺激显著增强了mRNA表达，表明在某些细胞类型中，FcεR2的合成也可能被特异性配体上调。
