Rooney I A, Davies A, Griffiths D, Williams J D, Davies M, Meri S, Lachmann P J, Morgan B P
Department of Medical Biochemistry, University of Wales College of Medicine, Heath Park, Cardiff, UK.
Clin Exp Immunol. 1991 Feb;83(2):251-6. doi: 10.1111/j.1365-2249.1991.tb05623.x.
Protectin (CD59 antigen) is a 20-kD phosphatidyl-inositol-linked membrane protein that inhibits formation of the membrane attack complex (MAC) of complement on homologous cells. Although the antigen has been identified in a number of human tissues, until recently a functional role had been demonstrated only in circulating cells. Using immunofluorescence techniques we have shown the presence of protectin on human glomerular epithelial cells (GEC) in culture and on GEC, tubular epithelial cells and endothelial cells in frozen sections of normal human renal cortex. In addition, we present evidence that this protein functions in protection of GEC from homologous complement: cultured cells incubated with the Fab2 fragment of a monoclonal anti-protein antibody were markedly more susceptible to killing by homologous serum than were cells in the absence of Fab2 anti-protectin. These findings suggest that this protein may be important in the maintenance of glomerular integrity in vivo, and may be of relevance in certain renal diseases.
保护素（CD59抗原）是一种20kD的磷脂酰肌醇连接膜蛋白，可抑制同源细胞上补体膜攻击复合物（MAC）的形成。尽管该抗原已在多种人体组织中被鉴定出来，但直到最近，其功能作用仅在循环细胞中得到证实。我们使用免疫荧光技术表明，培养的人肾小球上皮细胞（GEC）以及正常人肾皮质冰冻切片中的GEC、肾小管上皮细胞和内皮细胞上均存在保护素。此外，我们提供证据表明该蛋白在保护GEC免受同源补体攻击方面发挥作用：与单克隆抗蛋白抗体的Fab2片段孵育的培养细胞比未添加Fab2抗保护素的细胞更容易被同源血清杀死。这些发现表明，该蛋白可能在体内维持肾小球完整性方面起重要作用，并且可能与某些肾脏疾病有关。
