IL17A and granulomatosis with polyangiitis: Th17 cells promote the priming and recruitment of neutrophils, facilitate auto-antibody production and have direct, detrimental effects on parenchymal cells at the site of inflammation.[12,13] In GPA, it was shown that patients with active disease had higher levels of IL-17 than those in remission which could suggest a role for treatment targeting IL-17 in this disease.[14,15]