Immunohistochemical labeling of carbonic anhydrase isoenzymes in labial glands of infants

In salivary glands, the concurrent availability of HCO3^- is required for normal mucus release that is guaranteed by the carbonic anhydrases in this area. Due to lack of detailed carbonic anhydrase data in minor salivary glands, we identified various carbonic anhydrases (CA) in the human labial glands of infants in this study. Specifically, the CA isoenzymes II, III, IV, VI, VII, and XII were investigated in secretory and ductal epithelial cells. CA II was detected in serous glandular cells and sporadically in ductal cells, CA III in myoepithelial cells and skeletal muscle cells, CA IV in ductal cells, endothelial cells, erythrocytes, and skeletal muscle. The first immunohistochemical analysis of CA VII in salivary glands resulted in a positive reaction in serous glandular cells and ductal cells, as well as in skeletal muscle and endothelial cells. CA XII was sporadically localized at the basolateral membrane of ductal cells and in serous glandular cells. Mucous endpieces were negative in all carbonic anhydrases tested. Knowledge of carbonic anhydrases distribution in healthy tissues supports their assessment as biomarkers for cancer diagnosis, prevention, and therapy.