Abstract
The CD3 antigen is a surface structure associated with the T-cell receptor (TCR) to form a complex involved in antigen recognition and signal transduction. Reports on the structures of the CD3 molecules associated with alphabeta- and gammadelta-TCR have been contradictory. To investigate this issue, we raised a panel of monoclonal antibodies (mAb) against purified porcine CD3 molecules. Unlike the conventional anti-CD3, these mAb reacted specifically with peripheral gammadelta-T cells, but not with alphabeta-T cells. Immunoprecipitation showed that the antibody recognized a subset of CD3 molecules that were associated with gammadelta-TCR. Also unlike the conventional anti-CD3, these mAb, though directed at two different epitope groups, failed to induce antigenic modulation, T-cell proliferation and CD3-redirected cytotoxicity. Taken together, these results suggest that there are differences in the antigenicity, signal transduction potentials and probably structural differences between the CD3 molecules expressed at the surface of alphabeta- and gammadelta-T cells.