Primus F J, Finch M D, Masci A M, Schlom J, Kashmiri S V
Division of Immunology, Beckman Research Institute, City of Hope, Duarte, California 91010.
Cancer Res. 1993 Jul 15;53(14):3355-61.
The purpose of this study was to determine if human colon cancer cells transduced with monoclonal antibody (MAb) genes become sensitive to immune destruction through coexpression of both the MAb and its reactive antigen. Murine retroviral expression vectors were constructed with the heavy or light chain genes of an anti-human colon carcinoma MAb, D612, that mediates antibody-dependent cell-mediated cytotoxicity (ADCC). Transduction of D612 MAb genes into the D612 antigen-positive (> 95%) human colon carcinoma cell line, LS-174T, was carried out by sequential cocultivation with PA317 packaging cells producing infectious virions containing the light or heavy chain expression vectors. Six cultures survived drug selection, two of which were found to have elevated levels of both light and heavy immunoglobulin chain activity in their supernatants. IgG secretion levels (24 h) were 1-2 ng/1 x 10(6) cells. Low but definite antigen reactivity was also present in supernatants obtained from these LS-174T transductants. Immunocytochemical staining of transduced tumor cells revealed that > 95% of the cells were positive for IgG expression. Thus, LS-174T transductants were capable of producing both the D612 MAb and D612-reactive antigen. Analysis of transductants by flow cytometry further revealed that > 95% of the cells had murine immunoglobulin on their surfaces. ADCC mediated by human natural killer cells against nontransduced tumor cells was observed when the latter cells were co-cultivated in the presence of transductants producing both D612 heavy and light chains but not in the presence of tumor cells transduced with light chain only. LS-174T cells transduced with both D612 heavy and light chain genes were more sensitive to cytotoxicity mediated by natural killer cells than were light chain gene only transductants. ADCC contributed to the greater sensitivity of the former transductants to cytotoxicity based on its inhibition by anti-FcR gamma III antibody. Thus, these studies demonstrate that tumor cells transduced with genes encoding for MAbs that can participate in ADCC reactions are able to sensitize nontransduced tumor cells to immune destruction as well as to direct killer cells against themselves. These studies may lead to a new immunotherapeutic approach for the treatment of cancer based on MAb gene therapy.
本研究的目的是确定转导了单克隆抗体（MAb）基因的人结肠癌细胞是否通过MAb与其反应性抗原的共表达而对免疫破坏变得敏感。构建了携带抗人结肠癌MAb D612重链或轻链基因的鼠逆转录病毒表达载体，该MAb介导抗体依赖性细胞介导的细胞毒性（ADCC）。通过与产生含有轻链或重链表达载体的感染性病毒粒子的PA317包装细胞连续共培养，将D612 MAb基因转导至D612抗原阳性（>95%）的人结肠癌细胞系LS-174T中。6个培养物在药物筛选中存活，其中2个培养物的上清液中轻链和重链免疫球蛋白活性水平升高。IgG分泌水平（24小时）为1-2 ng/1×10⁶个细胞。从这些LS-174T转导子获得的上清液中也存在低但确定的抗原反应性。转导肿瘤细胞的免疫细胞化学染色显示，>95%的细胞IgG表达呈阳性。因此，LS-174T转导子能够产生D612 MAb和D612反应性抗原。通过流式细胞术对转导子进行分析进一步显示，>95%的细胞表面有鼠免疫球蛋白。当非转导肿瘤细胞在同时产生D612重链和轻链的转导子存在下共培养时，观察到人类自然杀伤细胞介导的针对非转导肿瘤细胞的ADCC，但在仅转导轻链基因的肿瘤细胞存在下未观察到。转导了D612重链和轻链基因的LS-174T细胞比仅转导轻链基因的转导子对自然杀伤细胞介导的细胞毒性更敏感。基于抗FcRγIII抗体对其的抑制作用，ADCC导致前者转导子对细胞毒性更敏感。因此，这些研究表明，转导了可参与ADCC反应的MAb编码基因的肿瘤细胞能够使非转导肿瘤细胞对免疫破坏敏感，并能引导杀伤细胞攻击自身。这些研究可能会导致基于MAb基因治疗的癌症新免疫治疗方法。
