Klint C, Truedsson L, Sturfelt G
Department of Medical Microbiology, University of Lund, Sweden.
Scand J Immunol. 1995 Oct;42(4):425-32. doi: 10.1111/j.1365-3083.1995.tb03676.x.
An in vitro model with human serum and human 0 Rh-negative erythrocytes was used for studies on preformed BSA/anti-BSA complex binding to complement receptor type 1 (CR1). The serum used was first depleted of Clq, factor D and properdin, then of C3, C4 or both and finally reconstituted with the desired proteins (serum reagent). With varying C4 concentrations and 100% C3 present, binding curves obtained for the two C4 isotypes were similar. When the serum reagent was not reconstituted with factor D and properdin there was no difference between the CR1 binding of normal serum and the partially reconstituted serum reagent, nor between the two C4 isotypes in this serum reagent. When C3 at 50% or 100% of normal concentrations was added to the serum reagent together with 100% C4A3 or C4B1, the C4B1-opsonized complexes showed more binding than the C4A3-opsonized complexes. At very low levels of C3 (< 25%) the binding could not be distinguished from the background. The results suggest that the binding of complement opsonized antigen/antibody complexes to erythrocyte CR1 is mediated mainly by C3, originating from activation of the classical pathway, and that the difference in properties between C4A and C4B does not have a major influence.
利用含人血清和人O型Rh阴性红细胞的体外模型，研究预先形成的牛血清白蛋白/抗牛血清白蛋白复合物与1型补体受体（CR1）的结合。所用血清首先去除C1q、D因子和备解素，然后去除C3、C4或两者，最后用所需蛋白质重新组成（血清试剂）。在C3浓度不同且C3含量为100%的情况下，两种C4同种型获得的结合曲线相似。当血清试剂未用D因子和备解素重新组成时，正常血清与部分重新组成的血清试剂在CR1结合方面没有差异，在这种血清试剂中两种C4同种型之间也没有差异。当将50%或100%正常浓度的C3与100% C4A3或C4B1一起添加到血清试剂中时，C4B1调理的复合物比C4A3调理的复合物显示出更多的结合。在非常低的C3水平（<25%）下，结合与背景无法区分。结果表明，补体调理的抗原/抗体复合物与红细胞CR1的结合主要由源自经典途径激活的C3介导，并且C4A和C4B之间的性质差异没有重大影响。
