Figure 4. Elevated numbers of inflammatory cells after A.baumannii infection in aged mice. Young and aged mice were infected intratracheally with 5×106 CFU LAC-4 and BALF were collected at 0 h and 24 hpi. Number of total cells (A), monocytes (B), macrophages (C), and neutrophils (D) in BALF of young and aged mice were determined. Data are presented as mean ± SEM of five mice per condition and represent one of 2 independent experiments. Statistical analyses were performed by Student’s t test. **, P < 0.01.