New monoclonal antibodies against the epithelioid cells in sarcoid granulomas.

Sarcoidosis is a systemic granulomatous disease of unknown etiology. Extensive investigations of granulomas have suggested several possible causes, but these are still controversial. We previously developed an anti-Kveim monoclonal antibody, IHY-1, which reacts with sarcoid granulomas as well as with epithelioid cells of various granulomatous diseases including tuberculosis. In the present study, we developed 2 new anti-Kveim monoclonal antibodies, IHY-2 and IHY-3, which react with epithelioid cells in sarcoidosis but not in tuberculosis. These antibodies reacted with a small population of alveolar macrophages in sarcoidosis and hypersensitivity pneumonitis by flow cytometry, as well as with most epithelioid cells in sarcoid granulomas by immunoperoxidase technique, suggesting that these cells expressed the antigen present in the Kveim reagent. Although the antigens recognized by these antibodies have not yet been identified, these monoclonal antibodies might become useful tools to elucidate the etiology of sarcoidosis.