Immunostaining of a representative frozen section of respiratory papilloma with antibody preparations to hBD-1 or hBD-2. Defensins were detectable as strong perinuclear staining of hBD-2 (A) and cytoplasmic immunostaining of hBD-1 (B) in all papilloma sections. Tissue section was counterstained with DAPI (C), and a merged picture was shown in (D). Arrows indicate areas of negative staining for hBD-1 and hBD-2 immunostaining. Tissue sections exposed to antibody preparations derived from preimmune or unrelated immunogens showed no reactivity (data not shown).