Characteristics of serum IgA and liver IgA deposits in alcoholic liver disease.

Patients with alcoholic liver disease frequently reveal an increase in IgA serum concentration and IgA deposits in a continuous pattern along hepatic sinusoids. We investigated whether the hepatic IgA deposits are a passive reflection of changes in concentration or composition of IgA in the circulation, or represent a distinct effect of alcohol on the liver. Forty-one patients with alcoholic liver disease (daily alcohol intake at least 50 gm for more than five consecutive years) were compared with 41 patients with nonalcoholic liver disease. Patients in both groups were matched for serum IgA and histopathological changes in the liver biopsy. IgA deposits in the liver were found in 78% of the alcoholic patients and in 12% of the nonalcoholic patients. The presence of deposits was not related to histopathological changes in the liver or to the serum IgA concentration. In serum IgA subclass distribution, alcoholic patients differed from nonalcoholic patients by a slight but significant shift to IgA2; in contrast, the hepatic IgA deposits in alcoholic patients were almost of the IgA1 subclass. Serum secretory component (which is an equivalent of serum secretory IgA) was elevated in both alcoholic and nonalcoholic patients; patients with a liver biopsy revealing hepatitis showed the highest level. In contrast, the hepatic deposits did not contain secretory component. We conclude that the continuous deposits of IgA along liver sinusoids are not a passive reflection of changes in concentration or composition of circulating IgA, but may represent a distinct effect of alcohol on the liver related to the role of this organ in IgA metabolism.