Lichen planus and chronic graft-versus-host reaction. In situ identification of immunocompetent cell phenotypes.

The purpose of the present study was to examine the phenotype of the cutaneous immunocompetent cells in lichen planus and chronic graft versus host (GVH) reaction infiltrates, by the use of monoclonal antibodies directed against T cell populations and Langerhans cells. Our results in lichen planus suggest an immunological reaction similar to the delayed hypersensitivity reaction, including all the immunocompetent cell subpopulations, with a first stage of antigenic information by Langerhans cells (OKT6+, BL6+, HLA-DR+) and helper cells, and a second stage mediated by suppressor/cytotoxic cells. The results from the study of GVH reaction also suggest an effect mediated by suppressor/cytotoxic cells (OKT3+, OKT4-, OKT8+, HLA-DR+). Our results favour the existence of a lymphocytotoxic process in lichen planus and chronic GVH reaction.