Immunohistochemical expression of granzyme B and perforin in discoid lupus erythematosus

Discoid lupus erythematosus (DLE) is a chronic photosensitive dermatosis characterized by scarring and atrophy. Granzyme B is a serine protease found in the cytoplasmic granules of cytotoxic lymphocytes and natural killer cells. Perforin permits delivery of the cytotoxic granzymes A and B into target cells to induce apoptosis and cause target cell death. The current study investigated the expression of granzyme B and perforin in 25 cases of DLE and in 10 cases of normal skin by immunohistochemistry and correlated their expression with the clinicopathological features in the studied DLE group. Both granzyme B and perforin were expressed in DLE with absent expression in normal skin. They were parallelly expressed in DLE where granzyme B was associated with features of chronicity such as old age (p = 0.05) and long duration of the disease (p = 0.05). Perforin expression in DLE was associated with male gender (p = 0.04) and outdoor workers (p = 0.04). Finally, expression of both granzyme B and perforin in dermal lymphocytic inflammatory infiltrate in DLE may indicate the cytotoxicity of the infiltrate. The parallel expression of both molecules may refer to the cooperative relationship between them to enhance cytotoxicity. Higher expression of granzyme B than perforin may indicate the presence of other pathways for granzyme B release independent from perforin.