Alam S Munir, McAdams Mildred, Boren David, Rak Michael, Scearce Richard M, Gao Feng, Camacho Zenaido T, Gewirth Daniel, Kelsoe Garnett, Chen Pojen, Haynes Barton F
Department of Medicine, Duke Human Vaccine Institute, Duke University School of Medicine, RP1 Circuit Drive, Durham, NC 27710, USA.
J Immunol. 2007 Apr 1;178(7):4424-35. doi: 10.4049/jimmunol.178.7.4424.
Two neutralizing human mAbs, 2F5 and 4E10, that react with the HIV-1 envelope gp41 membrane proximal region are also polyspecific autoantibodies that bind to anionic phospholipids. To determine the autoantibody nature of these Abs, we have compared their reactivities with human anti-cardiolipin mAbs derived from a primary antiphospholipid syndrome patient. To define the role of lipid polyreactivity in binding of 2F5 and 4E10 mAbs to HIV-1 envelope membrane proximal epitopes, we determined the kinetics of binding of mAbs 2F5 and 4E10 to their nominal gp41 epitopes vs liposome-gp41 peptide conjugates. Both anti-HIV-1 mAbs 2F5 and 4E10 bound to cardiolipin with K(d) values similar to those of autoimmune anti-cardiolipin Abs, IS4 and IS6. Binding kinetics studies revealed that mAb 2F5 and 4E10 binding to their respective gp41 peptide-lipid conjugates could best be defined by a two-step (encounter-docking) conformational change model. In contrast, binding of 2F5 and 4E10 mAbs to linear peptide epitopes followed a simple Langmuir model. A mouse mAb, 13H11, that cross-blocks mAb 2F5 binding to the gp41 epitope did not cross-react with lipids nor did it neutralize HIV-1 viruses. Taken together, these data demonstrate the similarity of 2F5 and 4E10 mAbs to known anti-cardiolipin Abs and support the model that mAb 2F5 and 4E10 binding to HIV-1 involves both viral lipid membrane and gp41 membrane proximal epitopes.
两种与HIV-1包膜糖蛋白41（gp41）膜近端区域发生反应的人源中和单克隆抗体（mAb）2F5和4E10也是能与阴离子磷脂结合的多特异性自身抗体。为了确定这些抗体的自身抗体性质，我们将它们与源自一名原发性抗磷脂综合征患者的人抗心磷脂单克隆抗体的反应性进行了比较。为了确定脂质多反应性在2F5和4E10单克隆抗体与HIV-1包膜膜近端表位结合中的作用，我们测定了单克隆抗体2F5和4E10与其标称的gp41表位相对于脂质体-gp41肽缀合物的结合动力学。抗HIV-1单克隆抗体2F5和4E10与心磷脂的结合解离常数（K(d)）值与自身免疫性抗心磷脂抗体IS4和IS6相似。结合动力学研究表明，单克隆抗体2F5和4E10与其各自的gp41肽-脂质缀合物的结合最适合用两步（相遇-对接）构象变化模型来定义。相比之下，2F5和4E10单克隆抗体与线性肽表位的结合遵循简单的朗缪尔模型。一种能交叉阻断单克隆抗体2F5与gp41表位结合的小鼠单克隆抗体13H11，既不与脂质发生交叉反应，也不能中和HIV-1病毒。综上所述，这些数据证明了2F5和4E10单克隆抗体与已知抗心磷脂抗体的相似性，并支持了单克隆抗体2F5和4E10与HIV-1的结合涉及病毒脂质膜和gp41膜近端表位的模型。
