Representative features of thymic stromal lymphopoietin immunodetection in liver biopsy specimens from patients with cryoglobulinemic vasculitis. Specific fluorescent staining is seen in the cytoplasm of hepatocytes (A), and especially in perinuclear areas (B). No nuclear staining is demonstrable. Thymic stromal lymphopoietin (TSLP) immunostaining is detected in inflammatory infiltrates of portal tracts (C) and in biliary epithelium (D, E). The fluorescence signal is completely abolished by preincubation of the anti-TSLP antibody with TSLP protein (F). FITC, fluorescein isothiocyanate.