Abstract
Murine monoclonal IgG1 and IgM anti-DNP hybridoma antibodies were examined for their ability to mediate ADCC by murine and human effector cells. Adherent and nonadherent BALB/c mouse spleen cells, as well as null cells obtained from nu-nu (nude) mouse spleen, were able to kill SRBC-TNP50 via IgG1 anti-DNP hybridoma. The cytotoxicity was inhibited by IgG, but not IgM or IgA myeloma proteins, and IgG2a was more effective than IgG1. ADCC of SRBC-TNP mediated by IgG1 hybridoma was highly dependent on the TNP substitution ratio. SRBC-TNP50 and SRBC-TNP20 were readily lysed, but SRBC-TNP10 to SRBC-TNP0.5 target cells were increasingly insensitive to cytolysis. IgG1 hybridoma-mediated ADCC was also observed with human peripheral blood lymphocytes, as well as T lymphocytes isolated by E-rosetting. Depletion of FcG-bearing peripheral blood T cells by EAG-rosetting eliminated the IgG1-mediated ADCC.
Sera from mice bearing three different IgM anti-DNP hybridomas with hemolytic titers of 1/60,000 to 1/400,000 and up to 600 µg/ml of antibody were unable to mediate ADCC by all populations of mouse effector cells examined. In addition, human effector cells enriched for FcM-bearing cells by depletion of EAG-rosetting cells were unable to kill SRBC-TNP50 in the presence of IgM anti-DNP hybridoma.
Contaminating heterophile antibodies capable of mediating ADCC to SRBC and CRBC were found in the sera of IgM hybridoma-bearing mice. The activity was directed against erythrocyte membrane determinants, and not TNP determinants, and could be completely removed by absorption with erythrocytes. This heterophile antibody-mediated ADCC could be inhibited by both IgG2a-and IgM-aggregated myeloma protein.
Footnotes
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↵2 Recipient of a Nuffield Foundation Travel Fellowship.
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↵3 Address reprint requests to: A. H. Greenberg, Manitoba Institute of Cell Biology, 700 Bannatyne Avenue, Winnipeg R3E OV9, Canada.
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↵1 This work was supported by the Medical Research Council of Great Britain and the Medical Research Council of Canada.
- Received October 30, 1978.
- Accepted May 8, 1979.
- Copyright © 1979 by The American Association of Immunologists, Inc.
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