抗－DNA免疫复合物性质的研究

CHARACTERIZATION OF ANTI-DNA IMMUNE COMPLEXES

用聚乙二醇（ＰＥＧ）和硫酸铵从系统性红斑狼疮（ＳＬＥ）患者血清中分离出免疫复合物（ＩＣ）和血浆核酸（ＰＮＡ）。分析结果表明，ＰＮＡ的主要成分是ＲＮＡ，仅有少量ＤＮＡ存在，并且ＰＮＡ中ＤＮＡ的ｄＧ＋ｄＣ含量（５５％）明显高于正常值（４２％）。一旦经过ＲＮａｓｅ处理，ＰＮＡ抑制抗－ＤＮＡ抗体结合ＤＮＡ的能力降低，说明抗－ＤＮＡ抗体和ＲＮＡ有交叉反应。动力学研究观察到，抗－ＤＮＡ免疫复合物中抗原抗体的分子比是１：１，结合能为３７ｋＪ／ｍｏｌ。这提示，除ＤＮＡ／抗－ＤＮＡ外，其他抗－ＤＮＡ免疫复合物也可能同ＳＬＥ患者的组织损伤有关。

Immune complexes (IC) and plasma nucleic acids (PNA) in the plasma of patients with systemic lupus erythematosus (SLE) were precipitated by polyethylene glycol 6000 (PEG-6000) and saturated ammonium sulfate. Results of the nucleic acid analysis showed that DNAs were only a portion of PNA and the major part of PNA was RNA. The dG+ dC content of DNA(55%)was much higher than that of normal human DNA (42 % ), After treated with RNase,PNA almost lost its inhibitive ability of the anti-DNA/DNA binding.implying that anti-DNA could cross-react with RNA. By applying enzymelinked immunesorbent assay (ELISA),the dissociation dynamics of anti-DNA IC was also studied. It was found that the molecular ratio and binding energy of antigens :anti-DNA antibodies in antiDNA immune complexes were 1 : 1 and 37kJ/mol respectively. These data raised the possibility that anti-DNA immune complexes,besides DNA/anti-DNA, might play an important role in the development of tissue injury in SLE patients.