Characterization of the polarized airway system and expression of anthrax receptors in NHBE cells. (A) TEM image of cross section obtained from untreated lung epithelial layers ALI-cultured for 5 weeks. A crosscut with apical cilia, different cell types including goblet cells, tight junction formation and cell interdigitations is depicted. Scale bar represents 5 µm. (B) Expression of differentiation markers caveolin 1, human defensins 1 (hBD-1) and 2 (hBD-2) in cell culture-plated cells (2D) versus polarized airway system (3D) (RT-PCR). Actin served as loading control. (C) Expression of surfactant A and B (SP-A, SP-B) in differentiated lung epithelial layers (RT-PCR of 3D, see B). PCR bands were not detected in 2D conditions (not shown). (D) Increased MUC5AC expression in polarized lung epithelium (RT-PCR). Actin was used as loading control. (E) Expression of anthrax receptors ATR/TEM8 and CMG2 in NHBE 2D (RT-PCR). Actin served as loading control. (1.34 MB TIF)