E2 treatment enhances IFN-α production induced by nucleic acid-containing immune complexes present in sera from SLE patients. PBMCs from postmenopausal women (5 × 105 cells/well) were stimulated with 1% SLE serum in the presence of different concentrations of necrotic supernatant from frozen-thawed (FT) PBMCs. IFN-α concentration in 24-hour culture supernatants was measured by ELISA. (A) IFN-α production by PBMCs from 2 representative postmenopausal women before (open bar) or after transdermal E2-therapy (solid bar). (B) Data obtained from 6 subjects before (S2) and after (S3) E2 treatment. PBMCs were stimulated as in panel A with 1% SLE serum with 15% FT, and IFN-α production was normalized to pDC numbers and expressed as picograms per milliliter pDCs. Individual data are shown, and bars represent mean values. P values were determined using the Wilcoxon signed rank test.