IgA antibody to lipid A in alcoholic liver disease.

To find out whether the increased immunoglobulin A (IgA) levels commonly reported in patients with alcoholic liver disease (ALD) are part of the immune response to gut-derived endotoxin antigen, an enzyme-linked immunoabsorbent assay was used to measure serum levels of antibodies to lipid A (the shared core of various lipopolysaccharides and the biologically active component of endotoxins) in patients with various diseases and in controls. Of 41 patients with ALD, 35 had significantly raised titres of IgA anti-lipid A. Rises of antilipid A were found in the secretory fraction of IgA as well, and titres of IgG antibody were also consistently increased. IgM titres were high in only 7 of 35 ALD patients tested. Patients with other diseases did not show significantly high titres of IgA antibodies to lipid A even though many had rises in total concentration of their serum IgA.