Whereas elastase is primarily required for clearance of certain Gram-negative bacteria, cathepsin G has been shown to be effective against infection with Gram-positive bacteria including Streptococcus pneumoniae and Staphylococcus aureus, as well as certain fungal infections (Tkalcevic et al., 2000; Reeves et al., 2002; Pham, 2006; Standish and Weiser, 2009; Hahn et al., 2011). Here, CTSG is linked to infection.