Functional properties and effect on growth suppression of human neuroblastoma tumors by isotype switch variants of monoclonal antiganglioside GD2 antibody 14.18.
Functional properties and effect on growth suppression of human neuroblastoma tumors by isotype switch variants of monoclonal antiganglioside GD2 antibody 14.18.
复制标题
单克隆抗神经节苷脂 GD2 抗体 14.18 的同种型转换变体的功能特性及其对人神经母细胞瘤生长抑制的影响。
作者：
K. Mujoo;T. Kipps;H. Yang;D. Cheresh;U. Wargalla;D. Sander;R. Reisfeld
在荧光激活细胞分选仪的帮助下，从产生抗GD 2单克隆IgG 3的杂交瘤14.18产生IgG同种型转换变体杂交瘤的完整家族。由相应同种型转换变体杂交瘤14 G1、14 G2 b或14 G2 a产生的IgG 1、IgG 2b和IgG 2a单克隆抗体（Mab）对生物化学定义的GD 2抗原和表达GD 2的神经母细胞瘤靶细胞系具有与14.18亲本细胞系产生的IgG 3 Mab相同的结合活性。这使我们能够检查每种抗GD 2抗体对表达GD 2的神经母细胞瘤细胞的相对体外和体内细胞毒性能力，而不依赖于抗体结合亲和力或特异性。由14.18、14 G2 a或14 G2 b而非14 G1产生的单克隆抗体可以在人补体存在下针对神经母细胞瘤肿瘤细胞指导有效的补体依赖性细胞毒性。由亲本14.18或14 G2 a产生的Mab在指导抗体依赖性细胞介导的细胞毒性方面比由14 G2 b产生的Mab更有效，并且14 G1的Mab是无活性的。然而，尽管存在这些体外差异，但由该开关变体家族的每个成员产生的抗体抑制BALB/c无胸腺nu/nu小鼠中人神经母细胞瘤肿瘤细胞的生长。这些研究表明，除了Fc-导向的补体依赖性细胞毒性或抗体依赖性细胞介导的细胞毒性之外的机制可能是这些特定抗体的体内抗肿瘤作用的原因。
A complete family of IgG isotype switch variant hybridomas was generated from the anti-GD2 monoclonal IgG3-producing hybridoma, 14.18, with the aid of the fluorescence-activated cell sorter. The IgG1, IgG2b, and IgG2a monoclonal antibodies (Mabs) produced by respective isotype switch variant hybridomas 14G1, 14G2b, or 14G2a, have binding activities for the biochemically defined GD2 antigen and GD2-expressing neuroblastoma target cell lines identical to that of IgG3 Mabs produced by the 14.18 parent cell line. This permitted us to examine the relative in vitro and in vivo cytotoxic capacities of each of the anti-GD2 antibodies for GD2-expressing neuroblastoma cells independent of antibody binding affinity or specificity. Mabs produced by 14.18, 14G2a, or 14G2b, but not 14G1, can direct efficient complement-dependent cytotoxicity against neuroblastoma tumor cells in the presence of human complement. Mabs produced by the parent 14.18 or by 14G2a are more efficient in directing antibody-dependent cell-mediated cytotoxicity than Mabs produced by 14G2b, and Mabs of 14G1 are inactive. However, despite these noted in vitro differences, antibodies produced by each member of this switch variant family suppress the growth of human neuroblastoma tumor cells in BALB/c athymic nu/nu mice. These studies suggest that a mechanism(s) other than Fc-directed complement-dependent cytotoxicity or antibody-dependent cell-mediated cytotoxicity may account for the in vivo antitumor effects of these particular antibodies.