S100A8 and infection: In plasma, low S100A8/A9 levels in uninfected mice (median 126 ng/ml) increased approximately 8-fold 5 days post-infection with S. Typhimurium irrespective of the inoculum (median 969 ng/ml with 105 CFU; 980 ng/ml with 106 CFU, P = 0.024; Fig 2A).