Fig. 7

Bleomycin-induced fibrosis promotes germinal center IgA⁺ B-cells and IgA⁺ plasma cells. (a) Mice were sacrificed 21 days after saline or bleomycin exposure and analyzed for fibrosis indices and inflammation. (b) Representative hematoxylin and eosin (h&e) staining of cryo-sections of lung tissue after PBS or bleomycin exposure. Histological analysis revealed that pulmonary fibrosis was present in mice 21 days after bleomycin exposure as shown by typical characteristics including thickening of alveolar walls with or without obvious damage and formation of fibrous bands. The dashed square shows a probable TLO structure, which showed a center GL-7-positive cells (present on GC B-cells) surrounded by IgD- positive naïve B-cells . (c) Total fibrosis score (TFS). The TFS is the product of the Ashcroft scale and level of lung involvement (see additional methods 1). ((d) Proportion of GC B-cells (CD19⁺CD95⁺IgD^low), IgA GC B-cells (CD19⁺CD95⁺IgD^lowIgA⁺), plasma cells (CD19^lowCD138⁺), and IgA⁺ plasma cells (CD19^lowCD138⁺IgA⁺) of alive cells in lungs. (e) Correlation of the proportion of GC B cells of alive cells in bronchoalveolar lavage fluid (BALF) and TFS. Non-parametric two-tailed Mann-Whitney test was used. Correlation coefficients were calculated using Spearman’s rank method. Data are expressed as mean and dots represent individual values of 4–7 mice per group and representative of 2 or more independent experiments. * P < 0.05 ** P < 0.01 *** P < 0.001