Fig. 2: pIgR^−/− mice spontaneously develop COPD-like lung pathology and adaptive immune activation.

a Representative image of emphysema in an 18-month-old pIgR^−/− and age-matched WT mouse (hematoxylin and eosin, scale bar = 50 μm). b Measurement of mean linear intercept (MLI), a morphometric measurement of emphysema, in WT and pIgR^−/− mice at the indicated ages. c Representative image of small airway wall thickening in an 18-month-old pIgR^−/− and age-matched WT mouse (Masson’s trichrome, scale bar = 50 μm). d Measurement of VV_airway, a morphometric measurement of small airway wall thickness, in WT and pIgR^−/− mice at the indicated ages. e Example of a tertiary lymphoid structure (TLS) in an 18-month-old pIgR^−/− mouse as indicated by immunostaining for B220. Scale bar = 50 μm. f Morphometric analysis of TLS area in lungs of WT or pIgR^−/− mice at the indicated ages. g–j Quantification of total, CD45⁺, CD19⁺, CD3⁺, CD4⁺, and CD8⁺ cells in the lungs of 18-month-old WT and pIgR^−/− mice by flow cytometry. b, d *p < 0.0001 compared to age-matched WT mice (2-way ANOVA with Bonferroni post hoc test); n = 5–6 mice group. f *p < 0.001 compared to 18-month-old WT mice (2-way ANOVA with Bonferroni post hoc test); n = 3 mice/group. g *p < 0.05 compared to 18-month-old WT mice (t-test); n = 9–12 mice/group. h *p < 0.05 compared to 18-month-old WT mice (Mann–Whitney test); n = 9–12 mice/group. i, j *p < 0.01 compared to age-matched WT mice (2-way ANOVA with Bonferroni post hoc test); n = 3–12 mice/group. Box-and-whisker plots represent median, interquartile range, and range.