RESUMEN
BACKGROUND: Lupus erythematosus (LE) and dermatomyositis (DM) are interface dermatitis, histologically characterized by formation of colloid bodies and a CD4+ CD8+ lymphocyte infiltrate. Colloid bodies are examples of intraepidermal apoptosis. Granzyme (Gr)B, synthesized by activated cytotoxic lymphocytes, is a serine protease able to prime apoptosis. GrB+ lymphocytes have been previously found in infiltrates in skin lesions from other types of interface dermatitis. AIM: To evaluate, on histological skin specimens from patients with LE and DM, GrB expression as a mediator of keratinocyte apoptosis in lymphocyte infiltrate. METHODS: In total, 22 patients with cutaneous LE [9 with discoid lupus erythematosus (DLE), 9 with subacute lupus erythematosus (SCLE) and 4 with systemic lupus erythematosus (SLE)] and 20 patients with DM were studied. Skin specimens underwent immunohistochemical staining with antibodies to CD3, CD4, CD8 and GrB. RESULTS: Immunohistochemical study with GrB was positive in 17 of the 22 patients with LE but only 2 of the 20 patients with DM. In LE, in systemic and subacute forms of LE, the median obtained was < 10 (+) whereas in the chronic forms, the median was 10-50% (++). Patients with DM were negative for GrB. CONCLUSIONS: In LE, a correlation between GrB+ lymphocyte and the presence of DLE form was found, but in DM, GrB is poorly expressed. GrB labels a subpopulation of effector cells involved in ongoing cytotoxic action and should be considered as a specific marker showing the extent of the direct local cytotoxic damage. GrB could play a role in the induction of skin apoptosis mechanisms in LE.