Crowley J J, Mageed R A, Silverman G J, Chen P P, Kozin F, Erger R A, Jefferis R, Carson D A
Department of Basic and Clinical Research, Scripps Clinic and Research Foundation, La Jolla, CA 92037.
Mol Immunol. 1990 Jan;27(1):87-94. doi: 10.1016/0161-5890(90)90063-6.
Cross-reactive idiotypes (CRI) on human rheumatoid factors (RF), which are identified by murine monoclonal antibodies (mAb), have proved useful in defining both the incidence and the structural characteristics of these autoantibodies. In this study, a new murine anti-idiotypic reagent, mAb B6, has been used to identify and define the expression of a distinct heavy chain CRI. The B6 CRI was found on 20% of monoclonal IgM (16 of 81), but on only 5% of monoclonal IgA (1 of 20) and on no monoclonal IgG. In addition, this CRI was expressed exclusively on a subset of Ig derived from the VHIII protein variable region subgroup. In immunoblotting experiments, the mAb B6 bound directly to the heavy (H) chains of CRI positive proteins. The B6 CRI was found frequently on monoclonal IgM-RF molecules, and the mAb B6 could inhibit the binding of the RF to its IgG antigen. It was also demonstrated that Staphylococcus aureus protein A (SpA), which has recently been shown to bind to the F(ab) region of VHIII molecules, could block the interaction of some B6 CRI positive IgM to the anti-CRI. These experiments suggest that the B6 CRI is a marker for one or a few VHIII genes and that it is expressed commonly on IgM paraproteins, many of which have RF activity.
由鼠单克隆抗体（mAb）鉴定出的人类类风湿因子（RF）上的交叉反应性独特型（CRI），已被证明在确定这些自身抗体的发生率和结构特征方面很有用。在本研究中，一种新的鼠抗独特型试剂，即mAb B6，已被用于鉴定和确定一种独特的重链CRI的表达。在20%的单克隆IgM（81个中有16个）上发现了B6 CRI，但在单克隆IgA中只有5%（20个中有1个）发现，而在单克隆IgG上未发现。此外，这种CRI仅在源自VHIII蛋白可变区亚组的Ig亚群上表达。在免疫印迹实验中，mAb B6直接与CRI阳性蛋白的重（H）链结合。B6 CRI经常在单克隆IgM-RF分子上发现，并且mAb B6可以抑制RF与其IgG抗原的结合。还证明，最近已显示能与VHIII分子的F(ab)区域结合的金黄色葡萄球菌蛋白A（SpA），可以阻断一些B6 CRI阳性IgM与抗CRI的相互作用。这些实验表明，B6 CRI是一个或几个VHIII基因的标志物，并且它通常在IgM副蛋白上表达，其中许多具有RF活性。
