Affiliations: [a] Ryerson Polytechnical Institute, Toronto, Canada | [b] National Laboratory for Immunology, Laboratory Centre for Disease Control, Ottawa, Canada
Note: [] Address reprint requests to Dr. K.C. Gupta, Department of Applied Chemical and Biological Sciences, Ryerson Poly technical Institute, Toronto, Ontario, Canada, M5B K3.
Abstract: Human tonsillar lymphocytes immunized in vitro with diphtheria toxoid were fused with the heteromyeloma cell line SP2/HPT. Hybrids were selected on hypoxanthine-thymidine aminopterin (HAT) medium and assayed for antibody production both by ELISA and Western blotting. Four stable hybridoma cell lines producing 3–7 μg/mL of human IgG1 antibodies were isolated. In Western blotting studies these antibodies show binding to the B fragment of diphtheria toxin. Cells from the subclone P2-13/G35 were injected i.p. in pristane-primed nude mice, and ascites fluid was collected after 4–6 weeks. The monoclonal antibody neutralized the cytotoxicity of diphtheria toxin in the Vero cell assay system. This human monoclonal antibody may have a potential in the immunotherapy of diphtheric disease.
Keywords: diphtheria toxin, human lymphocytes, in vitro immunization, human monoclonal antibodies, toxin neutralization, B fragment binding
