IL6 and granulomatosis with polyangiitis: Among the various cytokines and chemokines, interleukin (IL)-6 plays diverse and critical roles in the pathogenesis of MPA and GPA, owing to the following reasons: First, IL-6 secreted from antigen-presenting cells along with transforming growth factor beta may drive T helper (Th)17 cell differentiation, which, in turn, may accelerate tumour necrosis factor alpha and IL-1β production, thereby inducing neutrophil priming [2,3,4].