Davidson A, Lopez J, Sun D, Prus D
Department of Medicine, Albert Einstein College of Medicine, Bronx, NY 10461.
J Immunol. 1992 Jun 15;148(12):3873-8.
One of the hallmarks of rheumatoid arthritis (RA) is the production of high titers of rheumatoid factor (RF) antibody directed against the Fc portion of IgG. Anti-Id that recognize the majority of monoclonal RF from patients with B cell dyscrasias are reactive with only 1 to 2% of these polyclonal RF from RA patients. We describe a new monoclonal anti-Id, 4C9, that recognizes a L chain determinant on polyclonal IgM RF from patients with RA but does not recognize a panel of monoclonal RF from patients with B cell malignancies. 4C9 reactivity is found in the serum of 34/43 RF-positive RA patients and in 12/12 RF-positive synovial fluids, but in only 1/14 RF-negative sera from RA patients and 1/22 sera containing monoclonal IgM RF. 4C9 reactivity is highly enriched in purified IgM RF from nine RA patients and represents a variable percentage of total IgM RF up to a maximum of 23%. Furthermore, 4C9 reactivity is enriched in the synovial fluid of three of five RA patients compared with serum, suggesting that 4C9-reactive IgM RF are synthesized within the joint. IgG RF from RA synovial fluids are not 4C9 reactive, indicating either that different genes are used to encode IgM and IgG RF in RA patients, or that IgG RF have somatically mutated away from idiotypic reactivity.
类风湿关节炎（RA）的一个标志是产生高滴度的针对IgG Fc部分的类风湿因子（RF）抗体。识别B细胞发育异常患者大多数单克隆RF的抗独特型抗体，仅与RA患者这些多克隆RF的1%至2%发生反应。我们描述了一种新的单克隆抗独特型抗体4C9，它识别RA患者多克隆IgM RF上的轻链决定簇，但不识别B细胞恶性肿瘤患者的一组单克隆RF。在43例RF阳性的RA患者血清中有34例、12例RF阳性的滑液中有12例检测到4C9反应性，但在14例RA患者的RF阴性血清中只有1例、22例含有单克隆IgM RF的血清中只有1例检测到4C9反应性。4C9反应性在9例RA患者纯化的IgM RF中高度富集，占总IgM RF的可变百分比，最高可达23%。此外，与血清相比，5例RA患者中有3例的滑液中4C9反应性增强，这表明4C9反应性IgM RF是在关节内合成的。RA滑液中的IgG RF无4C9反应性，这表明要么RA患者中编码IgM和IgG RF的基因不同，要么IgG RF已发生体细胞突变而失去独特型反应性。
