A study assessing the effects of infection of IECs with STECs (97-3250: STEC O26: H11, 4865/96: STEC O145: H28) and HS (commensal E. coli O9:H4) on the expression of cytokine mRNA and protein found that 97-3250 promoted greater polymorphonuclear leukocytes (PMN) penetration than 4865/96 or HS by upregulating the expression of various chemokines, including CXCL8/IL-8, and by enhancing PMN chemotaxis. This evidence concerns the gene CXCL8 and infection.