DETECTION OF MONOMERIC AND POLYMERIC IGA CONTAINING IMMUNE-COMPLEXES IN SERUM AND KIDNEY FROM PATIENTS WITH ALCOHOLIC LIVER-DISEASE

Abstract

This study characterized circulating IgA and the IgA deposited in the glomeruli of patients with alcoholic liver disease. In the 6 patients studied there was an increased proportion in monomeric IgA (3.5-fold) and 9-13S IgA (8.94-fold), 13-17S IgA (4.49-fold) and 17-21S IgA (1.63-fold) fractions on 5-40% sucrose density gradient ultracentrifugation at physiological pH. All 9-21S fractions decreased at acid pH; a 3.28-fold increase occurred in fractions where polymeric IgA is expected to appear. IgA eluted at acid pH from autopsy kidney was studied by the same procedures. At pH 7.4 .apprx. 55% of this IgA sedimented at 9-21S, decreasing to .apprx. 25% at acid pH. The existence of true polymeric IgA in serum and kidney was based on the capacity of high MW IgA to bind human secretory component. The amount of monomeric IgA immune complexes was higher than that of polymeric IgA immune complexes in serum and in kidney. The percentage of heavy IgA (probably polymeric IgA) in kidney was higher than that in serum. The presence of high amounts of monomeric and polymeric IgA, both partially as immune complexes, was shown in serum and kidneys of patients with alcoholic liver disease and IgA glomerulonephritis. A role for human liver in the clearance of serum IgA, as has been demonstrated in some animal species, especially rats, is suggested.