In vitro, PVL activates PMNs to release potent proinflammatory mediators (IL-8 and leukotriene-B4) and granule enzymes (β-glucuronidase, hydrolase, and lysozyme) and to produce reactive oxygen metabolites that may cause tissue injury [6–10]. The gene discussed is CXCL8; the disease is periventricular leukomalacia.