Barbanti E, Corti A, Ghislieri M, Casero D, Rifaldi B, Portello C, Breme U, Trizio D, Marcucci F
Department of Immunology, Farmitalia Carlo Erba, Nerviano, Italy.
Hybridoma. 1993 Feb;12(1):1-13. doi: 10.1089/hyb.1993.12.1.
Tumor Necrosis Factor alpha (TNF alpha) is an inflammatory cytokine which exists mainly as a 51kD complex built up of 3 identical, noncovalently-linked polypeptide subunits. We have raised monoclonal antibodies (mAb) against human TNF alpha (huTNF alpha). One of these mAb (mAb78, mouse IgG1k) was studied in detail. mAb78 expresses a recurrent idiotype typical of the BALB/c anti-huTNF alpha antibody response. HuTNF alpha bound to mAb78 with an affinity constant (Kobs) of 3.2 x 10(10)M-1. The number of huTNF alpha-binding sites per mAb78 molecule was approximately 0.7. At concentrations higher than the Kobs mAb78 neutralized huTNF alpha at a approximately 1.3:1 molar ratio. mAb78 precipitated huTNF alpha in a double immunodiffusion assay in agar. Gel-filtration experiments of mAb78-huTNF alpha mixtures, that had been set up in large antigen excess, detected complexes of 570 kD as the smallest ones formed under these conditions. We propose that these results are accommodated best by a model according to which cyclic complexes built up of 3 mAb78 and 2 huTNF alpha molecules are the smallest units formed upon interaction of the reagents. In view of this model we discuss how huTNF alpha and mAb78 can undergo a precipitin reaction.
肿瘤坏死因子α（TNFα）是一种炎症细胞因子，主要以由3个相同的、非共价连接的多肽亚基组成的51kD复合物形式存在。我们制备了针对人TNFα（huTNFα）的单克隆抗体（mAb）。其中一种mAb（mAb78，小鼠IgG1κ）进行了详细研究。mAb78表达了典型的BALB/c抗huTNFα抗体反应的复发独特型。HuTNFα以3.2×10¹⁰M⁻¹的亲和常数（Kobs）与mAb78结合。每个mAb78分子的huTNFα结合位点数量约为0.7。在高于Kobs的浓度下，mAb78以约1.3:1的摩尔比中和huTNFα。mAb78在琼脂双免疫扩散试验中沉淀huTNFα。在大量抗原过量条件下建立的mAb78 - huTNFα混合物的凝胶过滤实验检测到570kD的复合物是在这些条件下形成的最小复合物。我们提出，这些结果最适合用一个模型来解释，根据该模型，由3个mAb78和2个huTNFα分子组成的环状复合物是试剂相互作用时形成的最小单位。鉴于此模型，我们讨论了huTNFα和mAb78如何发生沉淀反应。
