Fig. 3.
TLR-immunoreactive cells in human colonic specimens express an enteroendocrine cell (EEC) marker, serotonin. A: double staining of the colon with anti-serotonin (FITC) and anti-TLR1 (Texas red) antibodies. The asterisk shows a TLR1+serotonin+ cell in the intestinal crypt. Magnification: ×400. Scale bar = 50 μm. B: double staining of the colon with anti-serotonin (FITC) and anti-TLR2 (Texas red) antibodies. Asterisks show TLR2+serotonin+ cells in the intestinal crypt. Magnification: ×400. Scale bar = 50 μm. IECs expressing TLRs have features reminiscent of an EEC lineage, including a pyramidal shape with a large basolateral surface, an apically displaced nucleus, and a granular appearance.