In contrast, IL-10 and IL-4 deficiency made respective KO-mice more resistant to infection (Cenci et al., 1998, 2001; Del Sero et al., 1999; Clemons et al., 2000a): neutralization of IL-10 was reported to up-regulate production of nitric oxide, contributing to an effective fungicidal (Romani et al., 1994), and IL-4 cured 70% of infected mice when administered exogenously while protecting them from a second lethal challenge (Cenci et al., 1997). This evidence concerns the gene IL10 and infection.