Characterization of the porcine gammadelta T-cell receptor structure and cellular distribution by monoclonal antibody PPT27.

The T-cell receptor (TCR) is the critical structure involved in antigen recognition of T lymphocytes. Although the pig has a large proportion of circulating T lymphocytes bearing the gammadelta TCR, their study has been impeded due to the lack of specific antibodies. Here a monoclonal antibody (mAb) PPT27 directed to gammadelta TCR is described. Flow cytometry analyses showed that the mAb recognized a subset of T lymphocytes of which the majority expressed no CD2, CD4 and CD8 whilst the minority bore CD2 and CD8. The mAb precipitated a protein of 86 000 MW under non-reducing conditions and a doublet of 43 000 MW under reducing conditions from peripheral blood T lymphocytes lysed in nonidet P-40 buffer, whilst it precipitated the CD3-TCR complex from the cells lysed in digitonin. Further analysis revealed that the antibody recognized the majority, but not all, of the gammadelta T cells, suggesting that there may be more isotypes of gammadelta TCR than currently believed. The antibody was unable to stimulate gammadelta T cells to proliferate in vitro, suggesting that these cells are activated by a different activation mechanism from that of alphabeta T cells.