SERUM AND BAL CLARA CELL 10 KDA PROTEIN (CC10) LEVELS AND CC10-POSITIVE BRONCHIOLAR CELLS ARE DECREASED IN SMOKERS

Cigarette smoking has diverse effects on the structure and function of the lung, Smoking appears to reduce the levels of Clara cell 10 kDa p rotein (CC10) in the alveolar Lining fluid, but the influence of smoki ng serum on CC10 levels is still debated, and it has not been clear wh ether smoking reduces the number of CC10-producing lung cells, The aim s of this study were to clarify the influence of smoking on CC10 level s in the alveolar Lining fluid and bloodstream, and on the number of C C10-producing lung cells. CC10 concentrations were measured in sera an d bronchoalveolar lavage (BAL) fluids, by means of enzyme-linked immun osorbent assay using monoclonal and polyclonal antibody, and the immun ohistochemical expression of CC10 was examined in the lungs of nonsmok ers and smokers using the monoclonal antibody, TY-5, against CC10/huma n urinary protein-1. CC10 concentrations in sera and in BAL fluids fro m healthy smokers were significantly lower than in healthy nonsmokers, Immunohistochemical expression of CC10 was found exclusively in nonci liated bronchiolar epithelial cells, As compared to that of nonsmokers , the mean percentage of CC10-positive bronchiolar epithelial cells wa s significantly decreased in lung tissue specimens obtained from smoke rs who had normal results in pulmonary function tests. It was conclude d that smoking reduces the proportion of Clara cell 10 kDa protein-pro ducing bronchiolar epithelial cells, resulting in decreased levels of Clara cell 10 kDa protein in the lower respiratory tract and in the bl oodstream, The protein is a new blood biochemical and immunohistochemi cal marker, reflecting structural changes in peripheral airways induce d by cigarette smoking.