The composition and the pathological significance of C1q-binding immune complexes in MRL/lpr mice

我们以前的研究表明，在系统性红斑狼疮（SLE）患者中，大多数C1 q结合IgG是由C1 q胶原样区域的自身抗体组成。我们还发现，与人SLE相反，MRL/1小鼠中的C1 q结合IgG是含有DNA抗体的大尺寸免疫复合物。DNA酶I消化C1 q结合IgG不能降低C1 q结合活性，本研究对MRL/1小鼠C1 q结合免疫复合物中的抗原进行了研究。酶联免疫吸附试验（ELISA）检测层粘连蛋白和胶原，酶消化法（透明质酸酶、硫酸软骨素酶等）检测糖胺聚糖（透明质酸、硫酸软骨素、肝素、硫酸乙酰肝素）。这些免疫复合物的C1 q结合活性。此外，还研究了磷脂酶的影响，以确定脂质可能参与C1 q结合活性。然而，没有证据表明这些物质存在于C1 q结合免疫复合物中。

Our previous studies have shown that the majority of C1q-binding IgG in patients with systemic lupus erythematosus (SLE) is composed of autoantibodies to the collagen-like region of C1q. We also showed that C1q-binding IgG in MRL/l mice, in contrast to human SLE, is large-sized immune complexes containing antibodies to DNA.DNase I digestion of C1q-binding IgG failed to diminish C1q-binding activity, suggesting that other negatively-charged substances might be present as antigens in these C1q-binding immune complexes.This study was undertaken to characterize the antigens in C1q-binding immune complexes in MRL/l mice. Laminin and collagens were tested by ELISA, and glycosaminoglycans (hyaluronic acid, chondroitin sulfate, heparin, heparan sulfate) were examined by the effects of enzyme-digestion (hyaluronidase, chondroitinase, etc.) on C1q-binding activities of these immune complexes. In addition, the effects of phospholipases were also investigated for possible involvement of lipids in C1q-binding activity. No evidence, however, was obtained for the presence of these substances in the C1q-binding immune complexes.