IL17A and cystic fibrosis: Another key protein in CF physiopathology, significantly increased in this disease, is the pro-inflammatory cytokine IL-17 that regulates granulopoiesis and neutrophil recruitment; it is produced mainly by CD3+CD4+ T-helper (Th), although was also identified in other “innate-like” tissue-resident lymphocytes and in neutrophils [35,103].