To determine if the second wave of neutrophil recruitment in response to WT infection was due to induction of neutrophil-attracting chemokines, we analyzed the gene expression of KC, LIX and MIP-2 (ELR+ CXC chemokines that are important in neutrophil recruitment in mice and are functional homologues of IL-8 in humans) in lung samples on days 1, 2, 4 and 7 post-inoculation with 5×105 CFU of either WT or ΔPT strains. The gene discussed is CXCL8; the disease is infection.