Differential effects of tumour necrosis factor-alpha and interleukin-12 on isopentenyl pyrophosphate-stimulated interferon-gamma production by cord blood Vgamma9 T cells.

Lower numbers of Vgamma9Vdelta2 T cells in cord blood (CB) than in adult peripheral blood (PB), as well as their impaired ability to produce interferon-gamma (IFN-gamma) in response to stimulation, are associated with functional deficiency in the immune system in newborns. In this study, we stimulated CB Vgamma9 T cells with their T-cell receptor-specific ligand, isopentenyl pyrophosphate (IPP), plus exogenous costimulatory cytokines such as interleukin-2 (IL-2), IL-12 and tumour necrosis factor-alpha (TNF-alpha), which are known to play important roles in the activation of PB gammadelta T cells. Our data show that CB Vgamma9 T cells are able to produce IFN-gamma at levels comparable to PB Vgamma9 T cells by the addition of TNF-alpha in the presence of IPP and IL-2; however, under the same culture conditions, IL-12 does not efficiently activate CB Vgamma9 T cells to produce IFN-gamma. The frequency of TNF-alpha receptor II-positive Vgamma9T cells and the expression levels of TNF-alpha receptor II are similar in CB and PB; in contrast, the frequency of IL-12 receptor betaI (IL-12RbetaI) -positive Vgamma9T cells and expression levels of IL-12RbetaI are significantly lower in CB than PB. TNF-alpha but not IL-12 increases the expression of IL-2Rbeta on CB Vgamma9 T cells. These results provide new insights into the role of TNF-alpha in the activation of CB Vgamma9 T cells.