Human neutrophils express MHC Class II, either following in vitro activation via CD11b [8,9], with IFNγ, and GM-CSF [10,11] or following in vivo activation in RA synovial fluid [4,12], in patients with active Wegener's Granulomatosis [13], in patients receiving GM-CSF [14], and in persistent localized Staphylococcus aureus infections [15]. This evidence concerns the gene CSF2 and granulomatosis with polyangiitis.