TNF and infection: Lack of WSX-1 did not affect the proportion of Th1 cells that were IFN-γ+, TNF+ or both IFN-γ+TNF+ on days 0, 7 or 9 of infection (Figure 1D, E and results not shown); however, significantly higher frequencies of T-bet+Th1 cells derived from WSX-1−/− mice co-produced IFN-γ and TNF on day 14 of infection (Figure 1D, E) compared with cells from WT mice.