[UV-A exposure of the human epidermis enhances the binding of antibodies to SSA/Ro in vitro].

Normal and psoriatic skin specimens (n = 15) were processed to give 4-micron-thick frozen sections and exposed to a single UV irradiation in vitro. We used monochromatic UV-B (313 nm) and UV-A (365 nm). The doses were as follows: 10(3)/10(4) J/m2 (UV-B) or 4.10(3)/8.10(4) J/m2 (UV-A). We investigated the effect on epidermal binding of antibodies to SSA/Ro using the indirect immunofluorescence technique. Untreated and UV-B-treated human skin failed to bind anti-SSA/Ro. UV-A exposure disclosed reticular or granular staining of epidermal nuclei and a perinuclear halo. The effect was nearly the same throughout the dosage range. The combination of UV-A and methoxsalen increased the intensity of staining. Normal and psoriatic skin behaved in the same way.