CFTR targeting during activation of human neutrophils

Cystic fibrosis transmembrane conductance regulator (CFTR), a cAMP-activated chloride channel, plays critical roles in phagocytic host defense. However, how activated neutrophils regulate CFTR channel distribution subcellularly is not well defined. To investigate, we tested multiple Abs against different CFTR domains, to examine CFTR expression in human peripheral blood neutrophils by flow cytometry. The data confirmed that resting neutrophils had pronounced CFTR expression. Activation of neutrophils with soluble or particulate agonists did not significantly increase CFTR expression level, but induced CFTR redistribution to cell surface. Such CFTR mobilization correlated with cell-surface recruitment of formylpeptide receptor during secretory vesicle exocytosis. Intriguingly, neutrophils from patients with Delta F508-CF, despite expression of the mutant CFTR, showed little cell-surface mobilization upon stimulation. Although normal neutrophils effectively targeted CFTR to their phagosomes, Delta F508-CF neutrophils had impairment in that process, resulting in deficient hypochlorous acid production. Taken together, activated neutrophils regulate CFTR distribution by targeting this chloride channel to the subcellular sites of activation, and Delta F508-CF neutrophils fail to achieve such targeting, thus undermining their host defense function.