Chronic P. aeruginosa biofilm infections in cystic fibrosis patients are dominated by a Th2 response with increased and decreased levels of IL4 and IFNγ, respectively (Moser et al., 2000; Hartl et al., 2006), suggesting that P. aeruginosa biofilms persist by reducing host proinflammatory responses to infection. The gene discussed is IL4; the disease is infection.