Smith J W, Hayward C P, Horsewood P, Warkentin T E, Denomme G A, Kelton J G
McMaster University Medical Centre, Hamilton, Ontario, Canada.
Blood. 1995 Oct 1;86(7):2807-14.
The Gova/b alloantigens are expressed on a 175-kD protein (GP175) on human platelets. Anti-Gov alloantibodies have been implicated in posttransfusion purpura and alloimmune neonatal thrombocytopenia. In this report we characterize the immunochemistry of the alloantigens and identify the platelet protein that expresses the Gov epitopes. Approximately 50% of GP175 containing the Gov epitope was released from platelets treated with phosphatidylinositol-specific phospholipase C, indicating that at least some of this protein exists as a glycosylphosphatidylinositol (GPI)-linked isoform. Radioimmunoprecipitation and immunodepletion studies indicated that the Gova/b alloantigens are expressed on the GPI-anchored CDw109 protein. The Gova/b epitopes were expressed on an extracellular, 120-kD soluble fragment (p120) of CDw109 produced by calcium-dependent protease cleavage. Anti-Gov immunoprecipitates of chymotryptic digests of p120 contained 70- and 52-kD fragments of CDw109. Deglycosylation of native CDw109 had no effect on recognition by Gov alloantisera; however, the epitopes were destroyed after exposure to sodium dodecyl sulfate. Gova/b alloantigens were expressed on platelets and PHA-activated T-cells, cultured human umbilical vein endothelial cells, and by many different tumor cell lines, consistent with the tissue distribution of CDw109.
戈瓦/b同种异体抗原在人血小板上的一种175-kD蛋白（GP175）上表达。抗戈瓦同种异体抗体与输血后紫癜和同种免疫性新生儿血小板减少症有关。在本报告中，我们描述了同种异体抗原的免疫化学特性，并鉴定了表达戈瓦表位的血小板蛋白。用磷脂酰肌醇特异性磷脂酶C处理血小板后，约50%含有戈瓦表位的GP175从血小板中释放出来，这表明该蛋白至少部分以糖基磷脂酰肌醇（GPI）连接的异构体形式存在。放射免疫沉淀和免疫去除研究表明，戈瓦/a/b同种异体抗原在GPI锚定的CDw109蛋白上表达。戈瓦/a/b表位在由钙依赖性蛋白酶切割产生的CDw109的细胞外120-kD可溶性片段（p120）上表达。p120的胰凝乳蛋白酶消化产物的抗戈瓦免疫沉淀物含有70-kD和52-kD的CDw109片段。天然CDw109的去糖基化对戈瓦同种抗血清的识别没有影响；然而，表位在暴露于十二烷基硫酸钠后被破坏。戈瓦/a/b同种异体抗原在血小板、PHA激活的T细胞、培养的人脐静脉内皮细胞以及许多不同的肿瘤细胞系上表达，这与CDw109的组织分布一致。
