Tracheal epithelium and submucosal glands are predominant sites expressing Cytotoxic T Lymphocyte Antigen 2 alpha in the mouse

Cytotoxic T-lymphocyte antigen 2-alpha (CTLA 2-alpha) is cysteine proteinase inhibitor protein originally expressed in mouse activated T-cells and mast cells. Microarray, semi-quantitative PCR and Western blotting techniques identified CTLA 2-alpha as a novel lung tissue-specific secretory gene in the mouse. We also demonstrated the expression of CTLA 2-alpha in bronchiolar epithelial cells of the mouse lung. To extend these findings, we performed immunohistochemical analysis to determine the distribution of CTLA 2-alpha in the trachea. Results showed that CTLA 2-alpha is strongly expressed in pseaudostratified epithelium within columnar ciliated cells, and goblet cells that produce mucin. Staining was also evident in the submucosal glands within serous cells, and cuboidal cells lining ducts of submucosal glands. In the hyaline cartilage, CTLA 2-alpha was found in the cytoplasm of chondrocytes located in lacuna. The distribution pattern implicates an important role of CTLA 2-alpha in relation to immune defense of the trachea against infections and processing of secretions produced by the submucosal glands.