Aller S C, Cho D, Kim Y B
Department of Microbiology and Immunology, Finch University of Health Sciences, Chicago Medical School, Illinois 60064-3095.
Cell Immunol. 1995 Apr 1;161(2):270-8. doi: 10.1006/cimm.1995.1036.
G7 and PNK-E mAbs recognize distinct porcine NK cell and granulocyte function-associated molecules that enhance and induce a significant cytolytic response against tumor cell targets through a mechanism of re-directed cytotoxicity. The present study shows that the G7 and PNK-E molecules are present on the surface of porcine neutrophils, monocytes, and pulmonary alveolar macrophages as a physically and functionally associated cytolytic trigger molecular complex. Two-color flow cytometric analysis demonstrates that most, if not all, neutrophils are G7 and PNK-E antigen positive. In contrast, monocytes and PAM contain both G7 and PNK-E positive as well as G7 positive and PNK-E negative subpopulations. mAb binding competition experiments indicate that pretreatment of phagocytes with G7 mAb can block subsequent binding by PNK-E mAb, suggesting that these antigens are physically associated on the surface of porcine phagocytes. Fluorescent co-capping experiments utilizing G7 and PNK-E mAbs clearly demonstrate a physical association between G7 and PNK-E antigens present on the surface of porcine neutrophils. Pretreatment of phagocytes with F(ab')2 fragments of G7 and PNK-E mAbs shows that F(ab')2 G7 mAb blocks subsequent induction of phagocyte-mediated tumor cell cytotoxicity by whole PNK-E mAb but pretreatment with F(ab')2 PNK-E does not block subsequent induction of phagocyte-mediated tumor cell cytotoxicity by whole G7 mAb. In addition, pretreatment of neutrophils and mononuclear phagocytes with F(ab')2 fragments of G7 mAb blocks subsequent whole PNK-E mAb-dependent activation of a phagocytic cell intracellular oxidative burst response but pretreatment with F(ab')2 PNK-E does not block subsequent G7 mAb-dependent activation of a phagocytic cell intracellular oxidative burst response. These data reinforce a physical and functional association between the G7 and PNK-E molecules. Recent identification of the G7 antigen as the porcine homolog of Fc gamma RIII indicates that the G7 and PNK-E mAbs recognize a unique and previously uncharacterized Fc gamma R cytolytic trigger molecular complex present on the surface of porcine neutrophils, monocytes, and PAM.
G7和PNK-E单克隆抗体识别不同的猪自然杀伤细胞和粒细胞功能相关分子，这些分子通过重定向细胞毒性机制增强并诱导针对肿瘤细胞靶标的显著细胞溶解反应。本研究表明，G7和PNK-E分子以物理和功能相关的细胞溶解触发分子复合物形式存在于猪中性粒细胞、单核细胞和肺泡巨噬细胞表面。双色流式细胞术分析表明，大多数（如果不是全部）中性粒细胞为G7和PNK-E抗原阳性。相比之下，单核细胞和肺泡巨噬细胞包含G7和PNK-E均阳性以及G7阳性而PNK-E阴性的亚群。单克隆抗体结合竞争实验表明，用G7单克隆抗体预处理吞噬细胞可阻断PNK-E单克隆抗体随后的结合，这表明这些抗原在猪吞噬细胞表面物理相关。利用G7和PNK-E单克隆抗体进行的荧光共帽实验清楚地证明了猪中性粒细胞表面存在的G7和PNK-E抗原之间的物理关联。用G7和PNK-E单克隆抗体的F(ab')2片段预处理吞噬细胞表明，F(ab')2 G7单克隆抗体可阻断全PNK-E单克隆抗体随后诱导的吞噬细胞介导的肿瘤细胞细胞毒性，但用F(ab')2 PNK-E预处理不能阻断全G7单克隆抗体随后诱导的吞噬细胞介导的肿瘤细胞细胞毒性。此外，用G7单克隆抗体的F(ab')2片段预处理中性粒细胞和单核吞噬细胞可阻断随后全PNK-E单克隆抗体依赖性的吞噬细胞细胞内氧化爆发反应激活，但用F(ab')2 PNK-E预处理不能阻断随后G7单克隆抗体依赖性的吞噬细胞细胞内氧化爆发反应激活。这些数据强化了G7和PNK-E分子之间的物理和功能关联。最近将G7抗原鉴定为FcγRIII的猪同源物表明，G7和PNK-E单克隆抗体识别存在于猪中性粒细胞、单核细胞和肺泡巨噬细胞表面的一种独特且先前未表征的FcγR细胞溶解触发分子复合物。
