This suggests that Dppi, despite its importance in activating neutrophil serine peptidases like cathepsin G and elastase [30] and the demonstration of defective neutrophil responses and killing of some bacteria in cathepsin G and neutrophil elastase-deficient mice [2,35–37], does not overtly influence the severity or evolution of neutrophilic inflammation during the first 2 weeks of infection. Here, CTSC is linked to infection.