Abstract: In order to investigate the mechanism of ultraviolet in triggering and exacerbating cutaneous lupus erythematosus,we conducted an in vitro experiment to study the effect of UVB irradiaton on the expression of Ro/SSA antigen on cultured human keratinocytes by indirect immunofluorenscence(IIF).The results revealed that the treatment of keratinocytes with serial doses of UVB (50mJ/cm²,100mJ/cm²,200mJ/cm²) induced Ro/SSA antigen expression on the cell membrane.The Ro/SSA expression showed a dose dependent pattern with the maximal expression of 10 7% at the dose of 200mJ/cm².When 10^-5 mol/L 17 β estradiol was added to the culture medium 48 hours prior to 200mJ/cm² UVB exposure,it significantly increased Ro/SSA expression (17 2%) as compared with that induced by UVB alone(10.7%),which reveals that UVB irradiaton and estradiol treatment may bave synergetic action on the expression of Ro/SSA.From these results,we speculate that Ro/SSA expression on the surface of keratinocytes induced by UVB may function as an important trigger for antibody dependent keratinocyte damage in photosensitive cutaneous lupus erythematosus.

Key words: UVB, Keratinocyte, Ro/SSA