Langerhans cells in SLE skin. A role in lymphocyte migration and activation in situ

Langerhans cells in SLE skin and mucosa were studied by using monoclonal anti-T6 and anti-Ia antibodies and avidin-biotin-peroxidase complex staining. Langerhans cells were present in cell infiltrates of natural SLE skin lesions. In developing early skin lesions induced with test antigen, Langerhans cells were the predominant inflammatory cells, suggesting that migration of Langerhans cells into the inflammatory site in fact precedes lymphocyte migration. These findings agree with the hypothesis of the role of dendritic cells in lymphocyte circulation and antigen presentation under physiological and pathological conditions. Many of the infiltrating local T lymphocytes in both natural and test antigen induced SLE lesions were activated Ia+ cells. This suggests an active immune response in both natural and test antigen induced skin lesions in SLE. The low immunomodulatory T4/T8 ratio in situ in SLE skin lesions might suggest that T8+ cells exert immunosuppressive control on the local inflammation.