Fogler W E, Sun L K, Klinger M R, Ghrayeb J, Daddona P E
Department of Immunology, Centocor Inc., Malvern, PA 19355.
Cancer Immunol Immunother. 1989;30(1):43-50. doi: 10.1007/BF01665029.
A chimeric antibody was constructed in which the murine H- and L-chain variable regions of mAb 17-1A, raised against human colorectal cancer cells, were joined with the human constant mu and kappa regions. Transfection of these constructs into the murine myeloma Sp2/0 resulted in the expression and secretion of a pentameric Ig, designated chimeric 17-1A IgM. The chimeric 17-1A IgM was subsequently compared to a previously described chimeric 17-1A IgG1 for biological activities. Both chimeric mAbs were equally effective (weight basis) in competing against the binding of murine 125I-17-1A to cultures of HT-29 colon carcinoma cells. The calculated association constants for the chimeric 17-1A IgM and IgG1 were 1.63 x 10(8) l/mol and 3.41 x 10(7) l/mol, respectively. Unlike chimeric 17-1A IgG1, the chimeric 17-1A IgM was able to render colon carcinoma target cells susceptible to lysis by both xenogeneic (rabbit) and human complement. The extent of complement-mediated lysis dependent upon chimeric 17-1A IgM was correlated to 17-1A antigen expression on target cells. HT-29 colon carcinoma cells treated with chimeric 17-1A IgM did not directly result in antibody-dependent cellular cytotoxicity by human peripheral blood monocytes. However, chimeric 17-1A IgM greatly enhanced the deposition of C3 on complement-treated HT-29 cells, and concomitant incubation with monocytes resulted in heightened lysis of the tumor cells. The feasibility of enhancing host defense against gastrointestinal malignancies by the administration of this chimeric 17-1A IgM may have certain clinical advantages.
构建了一种嵌合抗体，其中针对人结肠癌细胞产生的单克隆抗体17-1A的鼠源重链和轻链可变区与人恒定μ链和κ链区域连接。将这些构建体转染到鼠骨髓瘤Sp2/0中，导致一种五聚体Ig的表达和分泌，命名为嵌合17-1A IgM。随后将嵌合17-1A IgM与先前描述的嵌合17-1A IgG1进行生物学活性比较。两种嵌合单克隆抗体在竞争鼠源125I-17-1A与HT-29结肠癌细胞培养物结合方面（以重量计）同样有效。嵌合17-1A IgM和IgG1的计算缔合常数分别为1.63×10⁸ l/mol和3.41×10⁷ l/mol。与嵌合17-1A IgG1不同，嵌合17-1A IgM能够使结肠癌靶细胞对异种（兔）和人补体介导的裂解敏感。补体介导的依赖于嵌合17-1A IgM的裂解程度与靶细胞上的17-1A抗原表达相关。用嵌合17-1A IgM处理的HT-29结肠癌细胞不会直接导致人外周血单核细胞产生抗体依赖性细胞毒性。然而，嵌合17-1A IgM极大地增强了C3在补体处理的HT-29细胞上的沉积，并且与单核细胞共同孵育导致肿瘤细胞的裂解增强。通过给予这种嵌合17-1A IgM来增强宿主对胃肠道恶性肿瘤防御的可行性可能具有一定的临床优势。
