Behçet's Syndrome (BS) is a systemic vasculitis characterized by variable vessel involvement and an elusive etiology, though immunogenetic studies strongly implicate the IL-23/IL-17 axis which bridges innate and adaptive immunity, orchestrating type 17 T-cell responses thus modulating neutrophil function- with this cell a central player in both BS clinical features and immunopathology. This evidence concerns the gene IL17A and necrotizing vasculitis.