As shown in Figures 4(b) and 4(d), pneumococcal infection resulted in an increase of TNFR2 mRNA expression in infected WT and IL-6−/− mice, whereas the infected TNFR1−/− and TNFR1-IL-6−/− mice did not show an induction of the expression. This evidence concerns the gene IL6 and pneumococcal infection.