Halo giant congenital melanocytic nevus: in vitro immunologic studies

We have assessed in vitro humoral and cell-mediated immune reactions of a patient with a giant congenital melanocytic nevus that showed clinical and histologic evidence of spontaneous regression. Nevus cell-specific antibody was detected in the patient's serum, which was cytotoxic to epidermal cells isolated from the pigmented nevus and specifically to cells of a human melanoma line in a complement-dependent fashion. The presence of epidermal Langerhans cells, known to be antigen-presenting cells, was required for nevus cell-specific activation of the patient's T lymphocytes. Antibody-independent inhibition of melanoma cell growth was detected by the use of the patient's mononuclear cells. Therefore both humoral and cell-mediated immunity may be involved in nevus cell rejection and halo formation.