Résumé
Elevated levels of secretory IgA in serum have been demonstrated in several liver dysfunctions such as hepatic cytolysis and cholestasis. However, these possible alterations at an eary stage of liver diseases have not yet been investigated. We studied a cohort of chronic alcoholic patients without cirrhosis in order to assess the changes in serum secretory IgA and other forms of secretory component, the split product of the polymeric Ig-receptor of epithelial cells. The possible diagnostic value of these measurements in the assessment of alcoholic disease was compared to that of serum gamma-glutamyl transpeptidase activity.
Serum levels of secretory IgA and IgM and free secretory component, were quantified by an enzyme-linked immunosorbent assay in 71 patients with chronic alcoholic liver disease without cirrhosis and in 45 healthy controls. Patients were divided into two groups according to the severity of the liver abnormalities. In addition, the reversibility of serum secretory IgA, IgM and free secretory component abnormalities after alcohol withdrawal was evaluated in 15 patients.
Serum levels of the three molecular forms of secretory component were significantly higher than those measured in control subjects, both in the whole population of patients and in the two groups of alcoholic patients without cirrhosis. In all groups, serum secretory IgA levels were correlated to free secretory component but not to total IgA levels. Serum secretory IgA levels were as discriminative as gammaglutamyl transferase activity in distinguishing between chronic alcoholic patients without cirrhosis and non-alcoholic subjects. The abnormalities of serum secretory IgA concentrations were reversible after alcohol withdrawal.
The results of this study demonstrate that serum secretory IgA and free secretory component levels are significantly increased in patients with chronic alcoholic liver disease, even at a very early stage of the disease, and decrease after alcohol withdrawal. Serum secretory IgA could therefore be used as an additional marker of mild liver abnormalities in chronic alcoholic subjects, and of the effectiveness of alcohol withdrawal. Release of polymeric Ig-receptor into the serum could share a similar physiopathological mechanism with gamma-glutamyl transpeptidase.