Ahmed A E, Veitch J, Whaley K
University of Glasgow, Department of Pathology, Western Infirmary, U.K.
Immunology. 1990 Jun;70(2):139-44.
Glycoprotein 60 (gp60) is a normal plasma protein (mean concentration in normal serum 34 micrograms/ml) that is present in increased levels (mean concentration 97 micrograms/ml) in the sera of patients with rheumatoid arthritis (RA). Purified gp60 binds to IgG but not to IgM, and competitively inhibits the binding of C1q. In fluid-phase studies, purified gp60 was shown to reduce immune complex-mediated complement activation in a dose-dependent manner. The addition of Fab anti-gp60 to normal serum was associated with (i) increased levels of complement-mediated prevention of immune precipitation (PIP); (ii) increased total haemolytic complement activity when EAIgG, but not when EAIgM, were used as targets; and (iii) increased immune complex-mediated complement activation. Thus gp60 appears to regulate immune complex-mediated classical pathway activation. The findings that Fab anti-gp60 (i) only partly restored PIP in RA sera showing reduced PIP levels and (ii) only partly reduced inhibition of PIP by RA sera, show that gp60 is not entirely responsible for these abnormalities.
糖蛋白60（gp60）是一种正常的血浆蛋白（正常血清中的平均浓度为34微克/毫升），在类风湿性关节炎（RA）患者的血清中水平升高（平均浓度为97微克/毫升）。纯化的gp60与IgG结合，但不与IgM结合，并竞争性抑制C1q的结合。在液相研究中，纯化的gp60被证明以剂量依赖的方式减少免疫复合物介导的补体激活。向正常血清中添加抗gp60 Fab与以下情况相关：（i）补体介导的免疫沉淀预防（PIP）水平增加；（ii）当以EA IgG而非EA IgM作为靶标时，总溶血补体活性增加；（iii）免疫复合物介导的补体激活增加。因此，gp60似乎调节免疫复合物介导的经典途径激活。抗gp60 Fab（i）仅部分恢复了PIP水平降低的RA血清中的PIP，以及（ii）仅部分降低了RA血清对PIP的抑制作用，这些发现表明gp60并非完全导致这些异常。
