Stimulating B cells with R848 (TLR7/8 agonist) and IFNα showed a trend toward an increase in the percentage of CD19+CD24hiCD38hi cells from CHC, but not in active on-treatment JDM patients [with PGA > 3.5 (range 0–10)] (Figures S5A,B in Supplementary Material). Here, CD19 is linked to juvenile dermatomyositis.