A UNIQUE SUBSET OF RAT AND HUMAN INTESTINAL VILLUS CELLS EXPRESS THE CYSTIC-FIBROSIS TRANSMEMBRANE CONDUCTANCE REGULATOR

Background/Aims: In the intestine, the cystic fibrosis transmembrane c onductance regulator (CFTR) has been localized to the apical pole of c rypt epithelial cells. Recent data indicate that some villus cells may also express CFTR, although the identity of these cells has not been established. The aim of the current study was to characterize the dist ribution, morphology, and surface marker expression of CFTR-expressing villus cells. Methods: Immunofluorescence and immunoelectron microsco py was performed using anti-CFTR and enzyme marker antibodies. Results : In the rat and human proximal small intestine, a subpopulation of sc attered villus and superficial crypt epithelial cells label brightly w ith anti-CFTR antibodies. The fluorescent signal is detected throughou t the cells with its greatest concentration apically. At the ultrastru ctural level, labeling involves the brush border and a prominent subap ical vesicular compartment. The cells resemble adjacent villus enteroc ytes in their abundance of mitochondria and expression of basolateral Na+-K+-adenosine triphosphatase yet differ in their absence of brush-b order sucrase and lactase expression. Conclusions: A previously unchar acterized subpopulation of villus cells with high levels of intracellu lar CFTR expression exists in the proximal small intestine. Morphologi cal and cytochemical studies suggest that this subset of villus cells has a unique transport function.