Serum levels of secretory immunoglobulin A in liver disease.

Secretory immunoglobulin A (sIgA) in serum was measured in patients with various liver diseases using enzyme immunoassay specific to sIgA. Marked elevation of the serum sIgA concentrations was found in liver diseases especially in intrahepatic or extrahepatic cholestasis. In chronic hepatitis and liver cirrhosis serum sIgA correlated significantly with leucine aminopeptidase (r = 0.69), GOT (r = 0.66), alkaline phosphatase (r = 0.55), and direct bilirubin (r = 0.42). In acute hepatitis their levels correlated significantly with total bilirubin (r = 0.59) and GPT (r = 0.55). In acute hepatitis and acute exacerbation of chronic hepatitis the major peaks of serum sIgA were observed later than those of liver enzymes. These results suggest two mechanisms working to elevate the serum sIgA levels in liver diseases. In chronic hepatitis, liver cirrhosis, and intrahepatic and extrahepatic cholestasis the raised serum sIgA probably reflects reflux of bile, a rich source of secretory component and sIgA, into circulation. In acute or chronic massive liver necrosis elevation of sIgA may be associated with liver regeneration. Serial measurement of serum sIgA with other conventional parameters will contribute much to the understanding of the pathophysiology of liver diseases.