Thus, to determine whether the increased DSS colitis severity in p47phox−/− mice was associated with a distinct pattern of leukocyte infiltration, DSS day 9 colon sections were evaluated using immunohistochemistry (IHC) for the presence of myeloperoxidase (MPO)-producing neutrophils, Mac-1-expressing myeloid cells (monocytes, macrophages, granulocytes), CD3+ T cells, and CD138+ plasma cells. The gene discussed is MPO; the disease is colitis.