Blood monocytes and serum and bone marrow lysozyme in sarcoidosis

Serum lysozyme (LZM) concentrations were correlated to the number of neutrophils and monocytes in patients with sarcoidosis and nongranulomatous diseases. In sarcoidosis patients with an increased activity of serum angiotensin converting enzyme (ACE), a positive correlation was noted between LZM and blood monocytes. In sarcoidosis patients with normal ACE activity, as well as in patients with non-granulomatous diseases, a correlation was found between blood neutrophils and LZM, but not between blood monocytes and LZM. LZM was found in bone marrow plasma and in serum in a ratio of 1.5 to 1. Sarcoidosis patients had 30% higher LZM levels than healthy controls. The concentration of LZM in bone marrow plasma did not correlate to detectable granulomas in bone marrow specimens. The positive correlation between blood monocytes and LZM in patients with clinically active sarcoidosis is possibly due to recruitment of bone marrow monocytes for the granuloma formation.