Fig. 7: The TGFβ-activating αvβ8 integrin on cDC1 licences IgA induction by this subset in vivo and in vitro.

a XCR1-β8^KO and littermate control (XCR1-β8^het) mice were orally challenged with RV. The total number of B cells, antigen-experienced IgD⁻ cells (left), total or RV-specific IgA⁺B220⁺CD138⁻ B cells (pre-gated on CD19⁺IgD⁻) (middle) and total or RV-specific IgA⁺ plasmablasts (B220⁻CD138⁺; pre-gated on CD19⁺IgD⁻) at 7 days post infection is plotted. Dots represent data from individual mice. Data were collected from three independent experiments with 4–5 mice per group each. b Splenic QM B cells were isolated by magnetic purification and cultured alone or with total CD11c⁺MHC⁺ DCs (+mLN DCs) isolated from mLN of C57Bl/6 mice in serum-free medium and in the presence of NP-Ficoll, anti-CD40 Ab and RA. Active TGFβ (act), latent TGFβ (lat) and/or a synthetic RGD (or RAD)-containing peptide were added as indicated. After 5 days cells were harvested and analysed for IgA expression by flow cytometry. Additional statistics: a₁-a₂, b₁-b₂, c₁-c₂, d₁-d₂ and e₁-e₂: *** (total n = 4-17) (c, d) CD103⁺ CD11b⁻ migratory cDC1 (+mig cDC1, (c, d)) or CD103⁺ CD11b⁺ migratory cDC2 (+mig cDC2, (c)) were sorted from the mLN of XCR1-β8^WT (C,D) or XCR1-β8^KO (d) mice as previously described and cultured with FACS-sorted QM B cells (gated as CD19⁺ B220⁺). Data is normalized to control cDC1 cultured with latent TGFβ + RAD for each replicate (total n = 4–7). Additional statistics: a₁-a₂, b₁-b₂, b₁-b₃:***, a₁-a₃:** Dots represent data from independent biological replicates. Data were collected from four (b) or three (c, d) independent experiments. Two-way ANOVA with Tukey post hoc was performed for statistical analysis. *p < 0.05, **p < 0.01, ***p < 0.001.