Fig. 3

Splenic marginal zone B cells and plasma cells show elevated MZB1 levels in aged lupus-prone mice. a MZB1 immunohistochemistry in young (10 weeks of age) and aged (30 weeks of age) BWF1 mice. Spleen, scale bar = 50 μm; kidney, salivary gland, scale bars = 20 μm. b Increased proportion of MZB1⁺ cells observed in various organs in aged BWF1 mice compared with young BWF1 mice (ANOVA, p < 0.05). c Spleen cells sorted as B220⁺CD21^high CD23^low (MZ B cells) and B220^–CD138⁺ (plasma cells). Percentages of B-cell subsets among total spleen cells in young (10–12 weeks of age) and aged (30–34 weeks of age) BWF1 mice compared with those in aged (30–34 weeks of age) B6 mice (n = 3–5 each group). Proportion of total MZ B cells increased on average by 8.8% in aged BWF1 mice compared with young BWF1 and B6 mice (ANOVA, p < 0.05). d MZB1 expression in each B-cell subset in young (10–12 weeks of age) and aged (30–34 weeks of age) BWF1 mice compared with aged (30–34 weeks of age) B6 mice (n = 3–5 each group). MZB1 expression in MZ B cells in aged BWF1 mice significantly higher than that in B6 mice (p < 0.05). In plasma cells, MZB1 expression in aged BWF1 mice significantly higher than that in young BWF1 and B6 mice (ANOVA, p < 0.05). e Representative histogram of MZB1 expression in MZ B cells in aged B6 mice and young and aged BWF1 mice. Blue line represents isotype control. GC germinal center, FoB follicular B, HPF high-power field, gland salivary gland, IF interfollicular area, LN lymph node, MZ B marginal zone B, w weeks, *p<0.05