Melanophages in inflammatory skin disease demonstrate the surface phenotype of OKM5+ antigen-presenting cells and activated macrophages.

Previous studies in our laboratory revealed that ultraviolet light induces the appearance of epidermal melanophages that have potent antigen-presenting ability, that can activate autoreactive T cells, and that exhibit the immunophenotype OKM5+, OKM1-, T6-, and DR+. Therefore we undertook immunophenotyping of melanophages in selected inflammatory mucocutaneous lesions to determine whether the OKM5+, OKM1- phenotype was limited to ultraviolet-induced inflammation or whether the occurrence of melanophages expressing this antigen-presenting cell phenotype was a more generalized phenomenon. Ten of the eleven patients with chronic inflammatory skin lesions demonstrated melanophages expressing the OKM5+, OKM1-, T6-, DR+ immunophenotype. In addition, they often expressed Mo3e, a marker of activated macrophages. In contrast, melanophages of a patient with post-inflammatory hyperpigmentation, although DR+, failed to express OKM5. These results are taken to support an active role for OKM5+, OKM1-, T6-, DR+ melanophages in inflammatory skin disease because these cells demonstrate the phenotype of activated inflammation-producing monocytes and potent antigen-presenting cells.