Detection of thymic stromal lymphopoietin and hepatitis C virus core proteins in the skin biopsies of cryoglobulinemic vasculitis patients by indirect immunofluorescence. Thymic stromal lymphopoietin (TSLP) immunoreactivity is present in the epidermis (A), both in basal (B) and suprabasal (C) layers. In the dermis, TSLP immune reactants are localized in the vessel walls (D). There is no TSLP signal in the skin of normal subjects (E). Intense signal of TSLP-specific immune reactants in human tonsil section as positive control (F). Hepatitis C virus (HCV) core protein immune deposits are found only in the dermis, whereas keratinocytes never displayed positivity (G). Intravascular HCV core immunostaining completely fills the vessel lumen (H, I) or is localized perivascularly (J). FITC, fluorescein isothiocyanate.