At the cellular level, MPO induces T cell proliferation in a dose dependent manner in antineutrophil cytoplasmic antibodies (ANCA) associated vasculitis and healthy donors [7], as well as having an immunosuppressive role, mediated by IL-10 [8] and by dendritic cell suppression through reduced CD86 and IL-12 expression (6). Here, MPO is linked to vasculitis.