Development of an enzyme-linked immunosorbent assay for Clara cell 10-kDa protein: in pursuit of clinical significance of sera in patients with asthma and sarcoidosis.

We have produced nine monoclonal antibodies to human CC10/protein-1 and analyzed their characterization. TY-5, TY-7, and TY-8 recognized restricted possible hydrophobic epitopes and their binding to CC10 prevented the other clones from CC10 binding, suggesting that these antibodies induce strong conformational change. TY-1, TY-2, TY-3, TY-6, and 6D4 recognize amino acid residues 61-68 and the presence of disulfide bonds might be essential for epitope expression of these five clones. The best combination was TY-1 and TY-2 in developing an enzyme-linked immunosorbent assay (ELISA), whereas TY-5 was most suitable for immunohistochemistry and immunoblotting. We found significantly lower serum CC10 levels in asthmatic subjects and higher serum CC10 levels in sarcoidosis subjects than in controls. Data of CC10 levels in BAL fluids of sarcoidosis subjects were similar to those in the circulation. CC10-positive epithelial cells were significantly lower in small airways of asthmatic subjects than in controls, and CC10-positive epithelial cells were inversely correlated with T cell and mast cell accumulation in the airways of asthmatic subjects. CC10 may be a downregulator in both Th1- and Th2-mediated chronic inflammatory diseases. The use of these MoAbs and recombinant CC10 is a powerful tool to investigate the clinical roles of CC10/P1 and the structure and function of CC10/P1.