Presence of a variant form of the estrogen receptor in peripheral blood mononuclear cells from normal individuals and lupus patients

Estrogen may participate in the pathogenesis of systemic lupus erythematosus (SLE) via its intracellular receptor. To investigate the presence of various isoforms of the estrogen receptor (ER) in SLE we isolated RNA from mononuclear cells of lupus patients and normal controls. Using RT-PCR we were able to identify both the full length wild-type form and an isoform of the ER which precisely lacks exon V in both patient and normal individuals. Our results, although limited, suggest that normal individuals can express both the wild-type and truncated version at the same time, whereas lupus patients only express either the wild-type or the truncated ER. This finding may lead to a better understanding of the reasons for the prevalence of lupus in females and of the estrogenic effects on SLE disease activity.