Activation of bovine peripheral blood γδ T cells for cell division and IFN-γ production

Bovine peripheral blood γδ T cells have been evaluated for effector function (IFN-γ production) and clonal expansion in a variety of systems including following activation by mitogens, IL-12, and stimulation, through the T cell receptor (TCR) with anti-CD3 monoclonal antibody (mAb), a cell-bound molecule and a soluble antigenic extract. To evaluate cell division, carboxyfluorescein succinimidyl ester (CFSE) loading of cells and flow cytometric analysis were used, while IFN-γ production was evaluated by intracytoplasmic staining. It was found that bovine γδ T cells produced IFN-γ and clonally expanded when stimulated through the TCR/CD3 complex by a cell-associated autologous molecule on monocyte, by bacterial components following in vivo sensitization of γδ T cells with a leptospira vaccine or by anti-CD3 mAb. In addition, γδ T cells were activated efficiently for effector function but not clonal expansion by culturing with IL-12. In contrast, stimulation by Con A or PMA/ionomycin induced efficient replication but only low level IFN-γ production which was not enhanced by the presence of IL-12. In several systems the amount of IFN-γ produced per cell by γδ T cells was less than that produced by CD4 T cells in the same cultures.