Utility of clinical examinations and anti-Kveim monoclonal antibody in the diagnosis of sarcoidosis

The most reliable method for a diagnosis of sarcoidosis is histological examinations. However, compatible histological findings were detected among 60% of cases and 40% of cases was diagnosed by clinical evidence only (Clinical sarcoidosis). We assessed the diagnostic reliability of the cases based on clinical features only with a comparison of positivity between definite and clinical sarcoidosis for different clinical examinations. Chest X-ray, ACE, PPD skin test etc., % positivity of BHL, ACE, PPD skin test and 67Ga scan were positive in more than 80% of definite cases but only 50% in clinical cases except for 67Ga scan. This finding means that it is necessary to develop new clinical laboratory methods to diagnose clinical sarcoidosis. From these points of view, we prepared a monoclonal antibody (IHY-1) to the sarcoid granulomagenic agent contained in Kveim suspension by immunizing mice with Kveim suspension. IHY-1 is an IgM monoclonal antibody that did not react with erythrocytes, lymphocytes, monocytes, alveolar macrophages or macrophage derived cell lines. It reacted with granuloma epithelioid cells of sarcoidosis-affected lymph nodes. Also in the granuloma of cases accompanied by tuberculosis, the monoclonal antibody positively reacted with epithelioid cells although the reaction was not strong.