Biological characterization of a chimeric mouse-human IgM antibody directed against the 17-1A antigen

Autor: Fogler, William E., Sun, Lee K., Klinger, Mark R., Ghrayeb, John, Daddona, Peter E.
Zdroj: Cancer Immunology, Immunotherapy; January 1989, Vol. 30 Issue: 1 p43-50, 8p
Abstrakt: Summary 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 µ and ? 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 murine125I-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 × 108 1/mol and 3.41 × 107 1/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 complementtreated 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.
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