Figure 4. T cell-directed TGF-β is required for GC B cell and isotype-switched antibody responses during influenza infection.
5 × 106 CD44lo Thy1.2+ CD4 T cells from TGF-βRIIf/f Lck-cre− (WT) or TGF-βRIIf/f Lck-cre+ (KO) mice were adoptively transferred into congenic Thy1.1+ OT-II TCR transgenic mice and infected with WSN-GP33/66 the following day. 14 days p.i., GC B cells (Fas+, GL7+ IgM−) (A) and IgG1+ GC B cells (B) in the MLN and spleen (SPL) were assessed by flow cytometry (left plots) and enumerated in bar graphs (right). (C) Splenic PNA+ GCs (green, highlighted by red ellipses) were assessed by immunofluorescent microscopy of frozen sections and the numbers of GC/tissue section was calculated using Imaris software. (D–E) Influenza-specific IgG and IgA were measured from bronchoaviolar lavage fluid (BAL) by ELISA at day 10 p.i. (D) or longitudinally at the indicated time points (E). Data in panels A–B are representative of four independent experiments (n = 3–5 mice/group/experiment). The bar graphs in panels C–D show cumulative data from two independent experiments (n = 3–5 mice/group/experiment), the images in panel C are from representative mice of these cohorts. *p < 0.05, **p < 0.005, ***p < 0.0005.