CXCL8 and infection: In addition, infection of neutrophils with WT, ΔT4, and UV-killed L. pneumophila strains resulted in IL-8 production compared to unstimulated cells (ANOVA, P < 0.0001) but IL-8 production of neutrophils induced by WT L. pneumophila was significantly less than the ΔT4, and UV-killed L. pneumophila strains (ANOVA, P < 0.0001) (Fig. 7C; Fig. S10A through E).