CXCR2 and cystic fibrosis: While the levels of IL-8 and lipopolysaccharide are increased in patients with CF (S1 Fig, [40–42]) and both of these molecules have been shown to decrease surface levels of CXCR2 [43, 44], it is intriguing that the surface levels of CXCR2 on leukocytes from CF patients were found to be elevated as compared to levels on cells from non-CF individuals (Fig 3).