Susceptibility to UVB light in cultured keratinocytes of cutaneous lupus erythematosus.

In this study, we investigated UVB-light-induced cytotoxicity and the binding of antibodies to extractable nuclear antigens on cultured keratinocytes from patients with cutaneous lupus erythematosus (LE). Keratinocytes from cutaneous LE patients showed a higher susceptibility to single-dose UVB light irradiation compared to keratinocytes from normal controls. The binding of antibodies to U1RNP and Ro/SS-A antigens on cultured keratinocytes was induced by UVB light and more up-regulated when cultured keratinocytes were reacted with autologous sera. Antibody-dependent cellular cytotoxicity (ADCC) was induced when cultured keratinocytes irradiated with UVB light were combined with autologous sera, using peripheral mononuclear cells of normal controls. Immunohistochemical studies of skin biopsy specimens from patients with systemic LE revealed an increased number of epidermal Langerhans cells at the peripheral sites of skin lesions and a relative dominance of infiltrative CD8-positive lymphocytes in the central area of skin lesions. Based on these findings we suggested that ADCC mechanisms were involved in the development of skin lesions, and the distribution of Langerhans cells and infiltrated CD8 cells were responsible for the expansion and persistence of lesions.