Bronchoalveolar lavage fluid (BALF) in patients suffering from granulomatosis with polyangiitis (Wegener’s) (GPA) demonstrated an increased neutrophil cell count, elevated MPO, CXCL8/IL-8 and G-CSF concentrations and the presence of antineutrophil cytoplasmic antibodies, suggesting that the innate immune system, in particular PMNs, are crucial effector cells in this disease (42). Here, CSF3 is linked to granulomatosis with polyangiitis.