Association of Clara cell 10-kDa protein, spontaneous regression and sarcoidosis.

Sarcoidosis is a systemic granulomatous disorder with a high rate of spontaneous regression. Clara cell 10-kDa protein (CC10), the predominant product of nonciliated bronchiolar epithelial cells, is a potent immunoregulatory and anti-inflammatory agent. CC10 levels were measured in sera and bronchoalveolar lavage (BAL) fluids from 31 sarcoidosis patients (nine progressive disease and 22 regressive disease) and their relevance to spontaneous regression investigated. The inhibitory effects of recombinant CC10 on interferon gamma (IFN-gamma) production were examined using lipopolysaccharide (LPS)-stimulated sarcoid BAL fluid cells, and the blocking effects of monoclonal antibody TY-5, directed against CC10, on CC10 function were also tested. Serum and BAL fluid CC10 levels in the regressive disease group were significantly higher than those in the progressive disease group (serum, p<0.05; BAL fluid, p<0.005) and healthy subjects (serum, p<0.0001; BAL fluid, p<0.005). CC10 inhibited, in part, IFN-gamma production from LPS-stimulated sarcoid BAL fluid cells (CC10 inhibition: 1,000 ng x mL(-1), 30%; 100 ng x mL(-1), 14%). TY-5 restored IFN-gamma production by blocking CC10 function. Sarcoidosis patients with regressive disease showed increased Clara cell 10-kDa protein levels in their sera and bronchoalveolar lavage fluids. Clara cell 10-kDa protein may be a regulator of the inflammatory process in sarcoidosis.