Ehrenstein M R, Hartley B, Wilkinson L S, Isenberg D A
Division of Rheumatology, University College London Medical School, UK.
J Autoimmun. 1994 Jun;7(3):349-67. doi: 10.1006/jaut.1994.1025.
Over the last decade a number of idiotypes (Id) have been identified on monoclonal IgM anti-DNA antibodies which represent germ-line genes. This study describes two new idiotypes present on a monoclonal human IgG anti-DNA antibody, D5 derived from a patient with active SLE. The two idiotypes, designated D5-RId and D5-MId, are defined by a polyclonal and monoclonal anti-Id respectively. Both anti-Ids inhibited each other's binding to D5 in an ELISA and did not bind to human IgG. Using western blotting the D5-RId was located on the light chain whereas the D5-MId bound to conformational determinants; both idiotypes were close to or at the binding site for DNA. The anti-Id reagents were used in ELISAs to screen human sera and tissue samples for the presence of the D5-MId and the D5-RId. The upper limit of normal for sera in the D5-MId ELISA was much lower than the D5-RId ELISA indicating a greater degree of specificity in the former. The idiotypes were found only in the IgG fraction of the sera. About 30% of SLE patients had either the D5-MId or the D5-RId and 20% had elevated levels of both, showing a considerable overlap in the expression of the two idiotypes. This overlap was also observed in the other disease groups including patients with other autoimmune diseases, though the numbers of patients expressing the idiotypes were significantly lower than in the SLE group. The idiotypes were present on both DNA binding and non-DNA binding fractions of lupus sera. D5-MId was present in 6/10 renal lupus biopsies and only in 2/15 disease control renal biopsies in which immunoglobulin was deposited. D5-RId did not stain any sections. There is a close correlation between the presence of the D5-MId and D5-RId in SLE sera and the level of expression. It is evident that both idiotypes are associated with SLE and are markers of a population of IgG anti-DNA antibodies, the isotype associated with active disease. Since the idiotypes are not found on IgM antibodies they are likely to be generated by somatic mutation.
在过去十年中，已在代表种系基因的单克隆IgM抗DNA抗体上鉴定出多种独特型（Id）。本研究描述了一种存在于源自一名活动性系统性红斑狼疮（SLE）患者的单克隆人IgG抗DNA抗体D5上的两种新独特型。这两种独特型，分别命名为D5-RId和D5-MId，分别由多克隆和单克隆抗独特型定义。在酶联免疫吸附测定（ELISA）中，两种抗独特型均抑制彼此与D5的结合，且不与人IgG结合。使用蛋白质印迹法，D5-RId位于轻链上，而D5-MId与构象决定簇结合；两种独特型均靠近或位于DNA结合位点。抗独特型试剂用于ELISA中，以筛查人血清和组织样本中D5-MId和D5-RId的存在情况。D5-MId ELISA中血清的正常上限远低于D5-RId ELISA，表明前者具有更高的特异性。独特型仅在血清的IgG部分中发现。约30%的SLE患者具有D5-MId或D5-RId，20%的患者两者水平均升高，表明两种独特型的表达有相当大的重叠。在包括其他自身免疫性疾病患者在内的其他疾病组中也观察到了这种重叠，尽管表达独特型的患者数量明显低于SLE组。独特型存在于狼疮血清的DNA结合和非DNA结合部分。D5-MId存在于10份狼疮性肾炎活检组织中的6份中，仅存在于15份有免疫球蛋白沉积的疾病对照肾活检组织中的2份中。D5-RId未对任何切片染色。SLE血清中D5-MId和D5-RId的存在与表达水平之间存在密切相关性。显然，两种独特型均与SLE相关，并且是一群与活动性疾病相关的IgG抗DNA抗体的标志物。由于在IgM抗体上未发现独特型，它们可能是由体细胞突变产生的。
