In contrast to these studies, it has been shown that IL-12 and IFN-γ can mediate protective effects against Streptococcus pneumoniae by promoting neutrophil accumulation [30] and that IFN-γ produced by neutrophils during Streptococcus pneumoniae infection was important in host defence as mice deficient in IFN-γ had impaired bacterial clearance [31]. This evidence concerns the gene IFNG and pneumococcal infection.