CXCR2 and infection: Aged individuals show increased neutrophil levels in airways/bronchoalveolar lavage fluid [373,374,375].Elderly patients with pneumococcal pneumonia show increased pulmonary infiltration of neutrophils [376].Some animal models show reduced neutrophil numbers at infection sites in aged mice (Staphylococcus aureus and Pseudomonas aeruginosa), even though local chemokine levels are high and circulating neutrophils express high CXCR2 levels [359,371,376]. However, other models of inflammation have given different results [377].