[The Ro/SSA antigen-antibody system. Studies of the effect of UVA-/PUVA irradiation and fibroblast activity on immune reaction with autoantibodies].

The Ro/SSA antigen-antibody system is of great importance with regard to the cutaneous manifestations and the photosensitivity of patients suffering from lupus erythematosus (LE). On account of in vitro investigations on cultured fibroblasts taken from psoriatic skin, we evaluated both the effect of UVA/PUVA irradiation and that of the metabolic activity of cells on this antigen-antibody system. We found that UVA irradiation is able to demask Ro/SSA. Thus it becomes accessible so subsequent antibody binding, which can be seen as nuclear fluorescence positive for IgM. Incubation of vital cells with these autoantibodies and subsequent irradiation resulted in a high degree of cytoplasmic fluorescence (IgG, IgM) in part of the fibroblasts exposed to UVA. Regarding the clinical application of light protective agents in LE patients with antibodies to Ro/SSA, UVA light--aside from UVB--should be taken into consideration.