Pietersz G A, Wenjun L, Sutton V R, Burgess J, McKenzie I F, Zola H, Trapani J A
Austin Research Institute, Austin Hospital, Heidelberg, Victoria, Australia.
Cancer Immunol Immunother. 1995 Jul;41(1):53-60. doi: 10.1007/BF01788960.
Mouse monoclonal antibodies to CD19 detect an antigenic determinant expressed exclusively on the surface of B lymphocytes, and have previously been shown to be potentially useful therapeutic reagents for human B cell lymphoma. We report the production and characterization of a mouse/human chimeric antibody, cCD19, with potent in vivo antitumour activity. The genes encoding the variable domains for heavy (VH) and light (VL) chains were subcloned into eukaryotic expression vectors containing human constant region genes (IgG1 and kappa), and co-transfected into non-secreting Sp2/0 mouse myeloma cells. Intraperitoneal administration of cCD19 produced inhibition of growth of subcutaneous CD19+ Sultan human B lymphoma tumours in scid/scid mice. When the antibody was administered 18 and 20 days after subcutaneous tumour inoculation, an approximately 30% reduction in tumour size was noted by day 29. cCD19 faithfully mimicked the in vitro binding characteristics of mCD19 as (a) the chimeric antibody was shown by flow cytometry to bind exclusively to cell lines that expressed CD19, (b) cCD19 was able to inhibit the binding of mCD19 on CD19+ cells completely and (c) the affinity of binding of the two antibodies was not significantly different [Ka = (2.03 +/- 1.5) x 10(8)]. In bio-distribution studies, up to 14.8% of the total injected antibody dose per gram of tissue was localized in CD19+ Sultan tumours at 24 h approximately, 14.4% was present in the tumors at 48 h, and about 13.7% at 72 h. These levels were comparable to mCD19 administered in the same fashion. cCD19 conjugated to idarubicin was specifically and strongly cytotoxic to CD19+ cells cultured in vitro, and demonstrated an IC50 of 0.17 microM, similar to that of mCD19 (0.32 microM) and approximately 14-fold greater than the IC50 of free idarubicin. The specific cytotoxic capacity of cCD19 and its likely reduced immunogenicity suggest that it may potentially be of use in the treatment of refractory B cell lymphoma in humans.
针对CD19的小鼠单克隆抗体可检测出仅在B淋巴细胞表面表达的一种抗原决定簇，并且先前已证明其可能是治疗人类B细胞淋巴瘤的有效治疗试剂。我们报告了一种具有强大体内抗肿瘤活性的小鼠/人嵌合抗体cCD19的制备及特性。编码重链（VH）和轻链（VL）可变区的基因被亚克隆到含有人类恒定区基因（IgG1和κ）的真核表达载体中，并共转染到不分泌的Sp2/0小鼠骨髓瘤细胞中。腹腔注射cCD19可抑制scid/scid小鼠皮下CD19+苏丹人B淋巴瘤肿瘤的生长。当在皮下接种肿瘤后第18天和第20天给予该抗体时，到第29天肿瘤大小约减少30%。cCD19忠实地模拟了mCD19的体外结合特性，因为（a）流式细胞术显示该嵌合抗体仅与表达CD19的细胞系结合，（b）cCD19能够完全抑制mCD19与CD19+细胞的结合，并且（c）两种抗体的结合亲和力无显著差异[Ka =（2.03±1.5）×10⁸]。在生物分布研究中，每克组织中注射的抗体总剂量的高达14.8%在约24小时时定位在CD19+苏丹肿瘤中，48小时时肿瘤中存在14.4%，72小时时约为13.7%。这些水平与以相同方式给予的mCD19相当。与伊达比星偶联的cCD19对体外培养的CD19+细胞具有特异性且强烈的细胞毒性，其IC50为0.17微摩尔，与mCD19（0.32微摩尔）相似，约为游离伊达比星IC50的14倍。cCD19的特异性细胞毒性能力及其可能降低的免疫原性表明它可能潜在地用于治疗人类难治性B细胞淋巴瘤。
