Class-switching of the IgM type anti-adenocarcinoma human antibody HB4C5 into an IgG1 type resulted in the loss of the antigen binding ability.
The heavy and light chain genes (mu and lambda) of the human anti-adenocarcinoma monoclonal antibody HB4C5 (MAb-C5) were cloned from the human-human hybridoma cell line HB4C5 and co-expressed in Chinese hamster ovary (CHO) and COS-7 cells. ELISA assay and the RI imaging of the cancer tissue xenografted into nude mice showed that the recombinant MAb-C5 retained the original antigen binding activity. We then replaced the IgM constant region of the MAb-C5 heavy chain gene with the human IgG1 constant region gene and co-expressed it with the light chain gene. This recombination was confirmed by a complete DNA sequencing and Western-blot analysis. Despite the fact that the DNA sequence, the expressed protein size, and the assembly of heavy and light chains were indicated to be normal, the IgG1 type MAb-C5 could not bind to the original antigen. This result suggest that this antibody alters its antigen binding property upon class-switching.
Haruta
H
H
Graduate School of Genetic Resources Technology, Kyushu University, Fukuoka, Japan.
Tachibana
H
H
Mochizuki
K
K
Hashizume
S
S
Kusakabe
K
K
Shirahata
S
S
Murakami
H
H
D000230:Adenocarcinoma / Q000000981:diagnostic imaging / Q000276:immunology*; D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000235:genetics / Q000276:immunology*; D000937:Antigen-Antibody Reactions / Q000276:immunology*; D001483:Base Sequence; D016466:CHO Cells; D019556:COS Cells; D006224:Cricetinae; D003574:Cytochrome c Group / Q000276:immunology; D004247:DNA; D004797:Enzyme-Linked Immunosorbent Assay; D006657:Histones / Q000276:immunology; D006801:Humans; D017578:Immunoglobulin Class Switching; D007075:Immunoglobulin M / Q000276:immunology*; D008175:Lung Neoplasms / Q000000981:diagnostic imaging / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D011877:Radionuclide Imaging; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology
D000911:Antibodies, Monoclonal; D003574:Cytochrome c Group; D006657:Histones; D007075:Immunoglobulin M; D011994:Recombinant Proteins; D004247:DNA