CXCL1 and infection: Similarly, IL-6 levels were significantly higher in WT mice than in C5ar1−/− mice infected with Spn alone (P<0.05 respectively).There were no significant differences in the levels of CXCL1/KC among wild-type and C5ar1−/− mice at 24 h infected with Spn alone, but there were significant differences at 48 and 72 h post infection.