Biological characterization of a chimeric mouse-human IgM antibody directed against the 17-1A antigen.
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.
Fogler
W E
WE
Department of Immunology, Centocor Inc., Malvern, PA 19355.
Sun
L K
LK
Klinger
M R
MR
Ghrayeb
J
J
Daddona
P E
PE
D000818:Animals; D000911:Antibodies, Monoclonal / Q000235:genetics / Q000276:immunology*; D000951:Antigens, Neoplasm / Q000276:immunology*; D003110:Colonic Neoplasms / Q000276:immunology* / Q000628:therapy; D003176:Complement C3 / Q000276:immunology; D003602:Cytotoxicity, Immunologic; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology; D007075:Immunoglobulin M / Q000235:genetics / Q000276:immunology*; D051379:Mice; D014407:Tumor Cells, Cultured
D000911:Antibodies, Monoclonal; D000951:Antigens, Neoplasm; D003176:Complement C3; D007074:Immunoglobulin G; D007075:Immunoglobulin M