Ortega E, Schneider H, Pecht I
Department of Chemical Immunology, Weizmann Institute of Science, Rehovot, Israel.
Int Immunol. 1991 Apr;3(4):333-42. doi: 10.1093/intimm/3.4.333.
We have recently described a monoclonal antibody, mAb G63, which identifies a novel membrane component of mast cells. This antigen is a glycoprotein with an apparent molecular mass of 28-40 kd, and is present on the surface of rat mucosal and serosal mast cells. Its density on cells of the mucosal mast cell line RBL-2H3 is 1 - 2 x 10(4) copies per cell. Crosslinking of this membrane protein by the intact mAb G63 results in a pronounced inhibition of the Fc epsilon RI-mediated secretion of RBL-2H3 cells. Here we show that crosslinking this novel membrane component inhibits biochemical processes initiated by Fc epsilon RI aggregation, such as the hydrolysis of phosphatidylinositides, the influx of Ca2+ ions, and the synthesis and release of de novo formed inflammatory mediators. Furthermore, by fluorescence microscopy, we show that crosslinking of Fc epsilon RI-IgE complexes by multivalent antigen results in redistribution of the membrane component recognized by G63, leading to its co-localization with the aggregated Fc epsilon RI. This localization is inhibited by NaN3, but not by colchicine or cytochalasin D. Fc epsilon RI crosslinking also promotes internalization of this novel membrane component. Taken together these data suggest that the mast cell membrane component recognized by mAb G63 is involved in the Fc epsilon RI-mediated stimulation of these cells, and thus can be considered a mast cell function-associated antigen (MAFA).
我们最近描述了一种单克隆抗体mAb G63，它可识别肥大细胞的一种新的膜成分。这种抗原是一种糖蛋白，表观分子量为28 - 40kd，存在于大鼠黏膜和浆膜肥大细胞的表面。其在黏膜肥大细胞系RBL - 2H3细胞上的密度为每个细胞1 - 2×10⁴个拷贝。完整的mAb G63使这种膜蛋白交联会导致RBL - 2H3细胞的FcεRI介导的分泌受到明显抑制。在此我们表明，使这种新的膜成分交联会抑制由FcεRI聚集引发的生化过程，如磷脂酰肌醇的水解、Ca²⁺离子内流以及新形成的炎症介质的合成与释放。此外，通过荧光显微镜观察，我们发现多价抗原使FcεRI - IgE复合物交联会导致G63识别的膜成分重新分布，使其与聚集的FcεRI共定位。这种定位受到NaN₃的抑制，但不受秋水仙碱或细胞松弛素D的抑制。FcεRI交联还促进这种新的膜成分的内化。综合这些数据表明，mAb G63识别的肥大细胞膜成分参与了FcεRI介导的这些细胞的刺激过程，因此可被视为一种肥大细胞功能相关抗原（MAFA）。
