CD30 and CD30L expression in regressing lesion (LyP, patient no. 4). Two-color immunofluorescence on frozen sections. (a) CD30 staining (FTIC, see Materials and Methods, original magnification × 200). Inset: particular of the area indicated by arrow. (b) CD30L staining (PE, see Materials and Methods, original magnification × 200). Inset: particular of the area indicated by arrow.