Fig. 4

Serum interferon- α (IFN-α) level is positively correlated with IFN-α producing capacity of imiquimod-stimulated plasmacytoid dendritic cells (pDCs) in systemic lupus erythematosus (SLE). Serum levels of IFN-α were measured by ELISA. The correlation of the serum IFN-α level with the SLE Disease Activity Index 2000 (SLEDAI) (a) and frequencies of CpG or imiquimod-induced IFN-α-producing pDCs (b) were examined by Spearman correlation