Immunohistochemical Study On The Distribution Of Beta-Defensin 1 And Beta-Defensin 2 Throughout The Respiratory Tract Of Healthy Rats

The distributions of beta-defensin 1 and 2 in secretory host defense system throughout respiratory tract of healthy rats were immunohistochemically investigated. In the nasal epithelium, a large number of non-ciliated and non-microvillous cells (NCs) were immunopositive for both beta-defensin 1 and 2, whereas a small number of goblet cells (GCs) were immunopositive only for beta-defensin 1. Beta-defensin 2-immunopositive GCs were few. In the nasal glands, a small number of acinar cells and a large number of ductal epithelial cells were immunopositive for both beta-defensins. In the laryngeal and tracheal epithelia, a very few NCs and GCs were immunopositive for both beta-defensins. In laryngeal and tracheal glands, a very few acinar cells and a large number of ductal epithelial cells were immunopositive for both beta-defensins. In the extra-pulmonary bronchus, a small number of NCs were immunopositive for both beta-defensins. A small number of GCs were immunopositive for beta-defensin 1, whereas few GCs were immunopositive for beta-defensin 2. From the intra-pulmonary bronchus to alveoli, a very few or no epithelial cells were immunopositive for both beta-defensins. In the mucus and periciliary layers, beta-defensin 1 was detected from the nose to the extra-pulmonary bronchus, whereas beta-defensin 2 was weakly detected only in the nose and the larynx. These findings suggest that the secretory sources of beta-defensin 1 and 2 are mainly distributed in the nasal mucosa and gradually decrease toward the caudal airway in healthy rats.