Induction of Ro/SSA antigen expression on keratinocyte cell membrane by heat shock and phorbol 12-myristate 13-acetate as well as estradiol and ultraviolet B.

Skin is one of the main target organs in lupus erythematosus and in some circumstances, skin lesions precede systemic manifestations. Previous studies have demonstrated that Ro/SSA antigen antibody might be involved in the pathogenesis of lupus erythematosus. The present study was performed to investigate the factors regulating expression of Ro/SSA antigens on the cell surface of keratinocytes. Cultured normal human keratinocytes were treated with 50-200 mJ/cm(2) of ultraviolet B (UVB) irradiation, 10(-9) to 10(-5) mol/l of 17beta-estradiol, 5-10 microg/l of phorbol 12-myristate 13-acetate (PMA), and 42 and 45 degrees C heat shock, respectively. The Ro/SSA antigen expressions were determined by indirect immunofluorescence. The results showed that keratinocytes receiving UVB irradiation expressed Ro/SSA antigen on cell membranes in a dose-dependent fashion. 17beta-estradiol treatment also induced Ro/SSA antigen expression dose-dependently. Keratinocyte expression of Ro/SSA antigens was also induced by heat shock stimulation. The 45 degrees C heat shock showed a stronger effect than 42 degrees C heat shock. Keratinocytes incubated for 24 h after heat shock had more antigen-expressing cells than those incubated for 6 h after heat shock. PMA at 5 and 10 microg/l also strongly induced Ro/SSA antigen expression. These results suggest that Ro/SSA antigen expression can be regulated by many factors and that protein kinase C signal transduction pathway might be involved in this process.