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.