Fig. 1.

IFN-λ is elevated in murine lupus. (A) IFN gene expression in healthy donor PBMCs. Cells were stimulated with the TLR7 agonist IMQ for 4 h and gene expression was quantified by qPCR (n = 4/group). (B) Schematic diagram of the IMQ-induced murine lupus model. (C) IFN-λ2/3 protein in murine lupus serum. Cytokine concentrations were measured by ELISA in mouse serum after 5 wk of IMQ treatment (n = 8 untreated, n = 16 treated). (D) Immunofluorescent staining for pDCs in murine lupus skin. TLR7 (green) and Siglec H (red) were detected in ear skin tissue after 5 wk of IMQ treatment. Tissue was counterstained with Hoechst (blue). (E) TLR7 expression in murine lupus skin. Gene expression was measured in ear tissue after 5 wk of IMQ treatment by qPCR (n = 4 WT, n = 4 Ifnlr1^−/−, n = 16 WT + IMQ, n = 12 Ifnlr1^−/− + IMQ). (F) IFN-λ2/3 production by pDCs. Mouse pDCs were isolated from splenocytes by MACS column and treated with 5 μg/mL IMQ for 24 h (n = 4 untreated, n = 5 IMQ). IFN-λ2/3 protein was measured by ELISA in culture supernatants. Optical density (OD) values were blank corrected and normalized to untreated samples. Data are represented as mean ± SEM. Statistics were calculated by nonparametric Mann–Whitney U test or one-way ANOVA with Sidak correction for multiple comparisons. *P < 0.05, **P < 0.01; ns, not significant. (Scale bars in D: 25 μm.)