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 ci rcumstances, skin lesions precede systemic manifestations. Previous studies have demonstrated that Ro/SSA antigen antibody might be involved in the pa thogenesis of lupus erythematosus. The present study was performed to inves tigate the factors regulating expression of Ro/SSA antigens on the cell sur face of keratinocytes. Cultured normal human keratinocytes were treated wit h 50-200 mJ/cm(2) of ultraviolet B (UVB) irradiation, 10(-9) to 10(-5) mol/ l of 17 beta -estradiol, 5-10 mug/l of phorbol 12-myristate 13-acetate (PMA ), and 42 and 45 degreesC heat shock, respectively. The Ro/SSA antigen expr essions were determined by indirect immunofluorescence. The results showed that keratinocytes receiving UVB irradiation expressed Ro/SSA antigen on ce ll membranes in a dose-dependent fashion. 17 beta -estradiol treatment also induced Ro/SSA antigen expression dose-dependently. Keratinocyte expressio n of Ro/SSA antigens was also induced by heat shock stimulation. The 45 deg reesC heat shock showed a stronger effect than 42 degreesC heat shack. Kera tinocytes incubated for 24 h after heat shock had more antigen-expressing c ells than those incubated for 6 h after heat shock. PMA at 5 and 10 mug/l a lso 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. (C ) 2000 Elsevier Science Ireland Ltd. All rights reserved.