Uptake of luminal FIX antigen by APCs in the small intestine. Immunohistochemistry of small intestine of hemophilia B mice. (A) Representative sections of villi from duodenum, jejunum, ileum, or (B) PP stained with antibody against FIX (red), F4/80 (green), and CD11c (blue) of mice fed with CTB-FIX expressing plant material. (C) Same stain of villi from ileum of a control mouse fed with WT material (NC, negative control). (D) Staining with antibody against FIX (red), CD103 (green), and CD11c (blue) of villi or (E) PPs from a mouse fed with CTB-FIX expressing or (F) WT plant material. Triangles in panel A point to yellow FIX⁺F4/80⁺ cells (yellow). Purple cells in panels A, B, and D are FIX⁺CD11c⁺ DCs. White/light blue cells in panels D and E are FIX⁺CD11c⁺CD103⁺ DCs (examples are indicated with triangles).