IL17A and cystic fibrosis: Moreover, innate and memory T cell-derived IL-17, as well as neutrophil-derived IL-17, are significantly increased in CF airways during pulmonary exacerbation which, in turn, is associated with increased production of the pro-neutrophilic cytokines CXCL8, IL-6, G-CSF and GM-CSF [39, 125–128].