Apoptosis is the mode of keratinocyte death in cutaneous graft-versus-host disease

Background: Satellite cell necrosis is a histopathologic hallmark of cutaneous graft-versus-host disease (GVHD) after allogeneic bone marrow transplantation. Although this interaction of lymphocytes with keratinocytes has features of immune cytolytic destruction, the details of the process are not known. Objective: Our purpose was to investigate whether apoptosis is involved in the process of GVHD. Methods: We used TdT-mediated dUTP-biotin nick end labeling (TUNEL) technique with biotinylated nucleotides. Formalin-fixed, paraffin-embedded sections from skin biopsy specimens of patients with GVHD and normal skin were studied. Results: Labeling of scattered individual keratinocytes in the epidermis and adnexal epithelium undergoing cytolytic degeneration and a proportion of the adjacent lymphocytes was noted in all specimens of GVHD. Conclusion: The positive staining of keratinocytes by the TUNEL method indicates that cell destruction in cutaneous GVHD involves apoptosis.