The neutrophil response to MV + LPS was attenuated in the lpr mice There were significantly less PMN in the BAL of lpr mice exposed to LPS + MV than in the B6 mice (2.2 x 0.5 x 10 3 vs 1.3 ± 0.2 x 10 4 cells, p < 0.05) (Figure 1-A) . A similar pattern was seen for lung MPO activity (Figure 1-B) . However, the lung concentrations of the PMN chemoattractants KC and MIP2 (CXCL2), although increased in response to MV + LPS, were similar in the lpr and B6 mice; this was also true for the pro-inflammatory cytokine TNFα (Figure 1 , C-F). Interleukin 6, GM-CSF, and VEGF were not affected by the administration of MV + LPS and were similar in the B6 and lpr mice (data not shown). These data suggest that both lung PMN recruitment and airspace PMN migration were impaired in the absence of functional Fas, but the difference in neutrophil recruitment seen in this model cannot be explained by differences in KC or MIP-2 release.