IL6 and infection: In the same way, compared with spleen cells from PBS-inoculated mice that were stimulated in vitro with TcAg, spleen cells isolated from infected mice inoculated with EV Y before infection produced approximately half the levels of pro-inflammatory cytokines TNF-α and IL-6 when stimulated in vitro with TcAg (Figures 3H,L, P < 0.01 and P < 0.0001, respectively).