CXCL2 and infection: In contrast, while the levels of the neutrophil chemoattractants, CXCL1 and CXCL2, in the BALF were significantly higher above baseline in the PA14 mice within 4 h after infection, this response was attenuated in mice pre-exposed to LPS, again showing a fine tuning of the inflammatory response by LPS (Fig. 1g).