Serum amyloid protein SAA, C-reactive protein and lysozyme in leprosy.

Serum amyloid protein (SAA) appears to be the precursor of amyloid protein AA, the non-immunoglobulin fibril protein of secondary amyloidosis. Since amyloidosis is known to occur in high frequency associated with lepromatous leprosy (LL), we have examined the SAA levels in untreated LL patients and compared them to the levels observed in patients with tuberculoid leprosy (TT) and a large number observed in healthy controls. We found that SAA is markedly elevated in LL when compared to TT and controls. No clear correlation could be established with C-reactive protein, a well-documented acute phase reactant, or serum lysozyme levels that reflect the presence of monocyte activity. This study showed that SAA levels in leprosy do not appear to be a reflection of inflammatory activity or monocyte turnover. Whether amyloidosis will be more prevalent in patients who have higher SAA levels remains to be determined.