IL6 and eosinophilic granulomatosis with polyangiitis: 1. G-CSF, GM-CSF, IL-6, IL-15, sIL-2Rα, and BCA-1/CXCL13 have been identified as a novel biomarkers of disease activity in GCA and EGPA. 2. Differences of biomarker levels between diseases independent of disease activity, were more apparent than differences related to disease activity.