Fig. 1.

B cell populations express IL-27. (A, B, and D) IL-27p28-eGFP mice were infected with 2 × 10⁶ PFU LCMV Cl-13 intravenously. (C) IL-27p28-eGFP mice and WT C57BL/6 mice were infected with 2 × 10⁶ PFU LCMV Cl-13. (A) Analysis of single-cell RNA-seq of splenocytes at days 1, 9, 25, and 30 p.i. (A, Left) Dimensionality-reduced uniform manifold approximation and projection (UMAP) plot and expression of cluster marker genes. (A, Right) Cluster distribution of IL-27p28-GFP⁺ and IL-27p28-GFP⁻ cells at each time point; the identity of each cluster is indicated by color. (B) Time-resolved distribution of cells within each cluster; the graph indicates relative abundances of IL-27p28-GFP⁺ (denoted IL-27-GFP⁺) and IL-27p28-GFP⁻ (denoted IL-27-GFP⁻) cells in each cluster scaled to peak relative abundance within each experimental group. (C) GFP expression on B cells (1, 25, and 30 d p.i.) or plasma cells (9 d p.i.) was determined by flow cytometry, gated on splenic B cells or plasma cells in IL-27p28-eGFP reporter mice and WT mice (the latter as a negative control for background fluorescence). (D) Frequencies of antibody-secreting cells (ASCs) in CD45.2⁺GFP⁺ and CD45.2⁺GFP⁻CD138⁻ populations were determined using IgG B cell ELISpot at day 9 p.i. Data in C and D are representative of two experimental replicates and the error bar represents mean ± SD from nine mice per group. FITC, fluorescein isothiocyanate; N.D., not detected.