Schulz T F, Scheiner O, Alsenz J, Lambris J D, Dierich M P
J Immunol. 1984 Jan;132(1):392-8.
Three murine monoclonal IgG1 kappa-antibodies, MAH-1, MAH-2, and MAH-3, were raised against factor H purified from human plasma. In cross-inhibition studies MAH-3 did not compete with MAH-1 and MAH-2, and vice versa, for the binding to H, whereas MAH-1 and MAH-2 inhibited each other. MAH-1 and MAH-2 inhibited the binding of H to C3b attached to an ELISA plate as well as to C3b bound to sheep erythrocytes by means of the classical pathway convertase and of C3b to H attached to an ELISA plate. The determinant defined by MAH-1 and MAH-2 was no longer accessible on H bound to C3b. In contrast, MAH-3 interfere with the binding of H to C3b or vice versa only to a smaller extent but recognized a determinant still accessible on H bound to C3b and was able to agglutinate EAC14o23b-H in an indirect Coombs test. All three antibodies were shown to bind to tonsil cells and Raji cells in an indirect cell ELISA. The membrane-associated molecule detected by these antibodies had an apparent m.w. of 140,000 D in SDS-PAGE. All three antibodies partially inhibited the binding of EAC14o23b to tonsil lymphocytes and, in the presence of 0.1 mM DFP, to Raji cells; binding of EAC14o23bi and EAC14o23d to tonsil cells was not affected. We conclude that MAH-3 recognizes a determinant distinct from the ones recognized by MAH-1 and MAH-2, the latter possibly defining identical epitopes that are located close to the binding site for C3b. The fact that these two distinct epitopes could be detected on a 140,000-D membrane-associated protein from lymphoid cells strongly suggests that this molecule is at least antigenically related to serum H and shares with H a region carrying the binding site for C3b. The rosette inhibition studies imply that this structure is important for the binding of C3b-coated particles to lymphoid cells.
针对从人血浆中纯化的H因子，制备了三种鼠单克隆IgG1 κ抗体，即MAH-1、MAH-2和MAH-3。在交叉抑制研究中，MAH-3与MAH-1和MAH-2在与H的结合上不相互竞争，反之亦然，而MAH-1和MAH-2则相互抑制。MAH-1和MAH-2抑制H与附着于酶联免疫吸附测定（ELISA）板上的C3b的结合，以及通过经典途径转化酶与结合于绵羊红细胞上的C3b的结合，还抑制C3b与附着于ELISA板上的H的结合。MAH-1和MAH-2所定义的决定簇在与C3b结合的H上不再可及。相比之下，MAH-3仅在较小程度上干扰H与C3b的结合或反之亦然，但识别在与C3b结合的H上仍可及的一个决定簇，并且能够在间接抗人球蛋白试验中凝集EAC14o23b-H。在间接细胞ELISA中，所有三种抗体均显示能与扁桃体细胞和Raji细胞结合。这些抗体检测到的膜相关分子在十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（SDS-PAGE）中的表观分子量为140,000道尔顿。所有三种抗体均部分抑制EAC14o23b与扁桃体淋巴细胞的结合，在存在0.1 mM二异丙基氟磷酸（DFP）的情况下，还抑制其与Raji细胞的结合；EAC14o23bi和EAC14o23d与扁桃体细胞的结合不受影响。我们得出结论，MAH-3识别的决定簇与MAH-1和MAH-2识别的决定簇不同，后者可能定义了位于靠近C3b结合位点的相同表位。在来自淋巴细胞的140,000道尔顿膜相关蛋白上能够检测到这两个不同的表位，这一事实强烈表明该分子至少在抗原性上与血清H相关，并且与H共享一个携带C3b结合位点的区域。玫瑰花结抑制研究表明，这种结构对于C3b包被颗粒与淋巴细胞的结合很重要。
