Monteiro R C, Cooper M D, Kubagawa H
Howard Hughes Medical Institute, University of Alabama, Birmingham 35294.
J Immunol. 1992 Mar 15;148(6):1764-70.
Fc alpha receptors (Fc alpha R) were isolated from a human monocytic cell line and used to raise four mAb with receptor specificity. The antibodies were used to identify the types of white blood cells that express Fc alpha R and the molecular heterogeneity of the receptor molecules. Nonpolymorphic epitopes, outside of the Fc alpha-binding site, were recognized only on blood cells of granulocyte and monocyte/macrophage lineages. The molecules identified, both by the antibodies and by the IgA ligand, were glycoproteins ranging in relative molecular mass from 55 to 75 kDa. However, one antibody detected a subpopulation of Fc alpha R molecules characterized by relatively restricted size heterogeneity. A complex glycosylation pattern was revealed by the resolution of discrete 32- and 36-kDa molecular species after removal of N-linked oligosaccharides and by evidence for O-linked carbohydrate moieties on at least a portion of the Fc alpha R molecules. In biosynthetic studies, all four anti-Fc alpha R antibodies and the IgA ligand bound a single 32-kDa core protein present in tunicamycin-treated cells, and the exceptional antibody again recognized molecules with relatively restricted glycosylation in the nontreated cells. These antibodies and native IgA ligands thus provide complementary reagents for definition of the complex structure and function of Fc alpha R in systemic IgA antibody responses.
从人单核细胞系中分离出Fcα受体（FcαR），并用于制备四种具有受体特异性的单克隆抗体（mAb）。这些抗体用于鉴定表达FcαR的白细胞类型以及受体分子的分子异质性。在Fcα结合位点之外的非多态性表位仅在粒细胞和单核细胞/巨噬细胞谱系的血细胞上被识别。通过抗体和IgA配体鉴定出的分子是相对分子质量在55至75 kDa之间的糖蛋白。然而，一种抗体检测到了FcαR分子的一个亚群，其特征是大小异质性相对受限。去除N-连接寡糖后，通过解析离散的32 kDa和36 kDa分子物种以及至少一部分FcαR分子上存在O-连接碳水化合物部分的证据，揭示了复杂的糖基化模式。在生物合成研究中，所有四种抗FcαR抗体和IgA配体都结合了衣霉素处理细胞中存在的单一32 kDa核心蛋白，并且该特殊抗体再次识别未处理细胞中糖基化相对受限的分子。因此，这些抗体和天然IgA配体为定义FcαR在全身IgA抗体应答中的复杂结构和功能提供了互补试剂。
