To find the correlation of the numbers of PMNs at various time points with the severity of the disease in mice infected with E. coli, the PLCs of the mice were collected at 18, 48, and 72 hours after infection, counted by hemocytometer or flow cytometry after staining with fluorescence-labeled mAb of anti-CD45 and anti-CD11b. This evidence concerns the gene ITGAM and infection.