Immunohistochemical demonstration of lysozyme in the lymph nodes and Kveim reaction papules in sarcoidosis.

Lysozyme (LZM) was demonstrated by an immunoperoxidase method in some but not all epitheloid-cell granulomas, free macrophages and giant cells in the lymph nodes and Kveim reaction papules of patients with sarcoidosis. In inactive disease, LZM staining was weak or absent in fibrotic lymph nodes. The pattern of LZM staining in Kveim reaction papules was similar to that seen in the "active" sarcoid lymph nodes. The presence of LZM in sarcoid tissue explains the high concentration of serum LZM in patients with active sarcoidosis and the extent of LZM distribution in tissues is probably an index of disease activity.