CT imaging and histological examination of bowels affected by neutropenic enterocolitis. (A-B) Abdominal computed tomography (CT) imaging of patients (G2, left; G1, right) being treated with a GO-containing therapy regimen with grade 4 enteritis/colitis. Clinical and CT-based findings confirmed them to be cases of neutropenic enterocolits; red arrow indicates colonic wall thickening; yellow star, ascites and peritoneal contrast enhancement as a sign of peritoneal irritation. Immunohistochemistry was performed on 6-μm sections of formalin-fixed, paraffin-embedded tissue. After antigen retrieval, slides were incubated with antibodies against CD33 (PWS44; Leica) or cleaved caspase-3 (5A1E; 1:200; Cell Signaling Technology). The signal was visualized using the ImmPress anti-rabbit immunoglobulin G polymer kit (Vector Laboratories) according to the manufacturer's instructions. The total number of positive cells was quantified in 10 HPFs. H&E(hematoxylin and eosin) staining of colon (normal [C] and colitis [F]). CD33 stains stromal cells in normal (D) and inflamed colon (G), whereas no staining is observed in epithelial cells. Immunohistochemistry for cleaved caspase 3 (normal [E] and colitis [H]) highlights apoptotic epithelial cells (indicated by red arrow). Panels F-H are specimens of the ileocecal resection of a patient being treated with 3+7 + GO (G2).