Presence of apoptotic cells and phagocytosis by macrophages comparing controls and patients with or without infiltrates. (a) Numbers of sunburn cells (SBCs) in patients with infiltrates, patients without infiltrates, and controls before and up to 10 days after irradiation. ■, patients with infiltrates (IP); ●, patients without infiltrates (P); ○, controls (C). Extensive phagocytosis of apoptotic keratinocytes by macrophages in the epidermis of patients with infiltrates. (b) Representative biopsy showing CD68 staining combined with haematoxylin staining using diaminobenzidine (DAB) for visualisation of CD68-positive cells. Magnification, ×400. Two macrophages that contain multiple phagocytic vacuoles (black arrows) are shown. One vacuole clearly contains an apoptotic cell (checkered arrow). (c) Representative biopsy showing CD68 staining using DAB for visualisation, combined with haematoxylin eosin staining. Magnification, ×400. White arrow indicates macrophages not involved in phagocytosis, and checkered arrows indicate eosinophilic particles that are being ingested by macrophages. UVB, ultraviolet B light.