The purpose of this study was to characterize 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
IgA between 9-13S (8.94 fold), 13-17S (4.49 fold) and 17-21S (1.63 fold) fractions on 5-40%
sucrose density gradient ultracentrifugation at physiological pH. All fraction between 9.12S decreased at
acid pH, however a 3.28 fold increase in fractions where
polymeric IgA is expected to appear.
IgG eluted at
acid pH from autopsy kidney was studied by the same procedures. At pH 7.4 about 55% of that
IgA have a molecular weight comprised between 9-12S, decreasing to around 25% at
acid pH. The existence of true
polymeric IgA in serum and kidney was based on the capacity of high molecular weight
IgA to bind human
secretory component. The amount of
immune complexes with monomeric
IgA were higher than those with
polymeric IgA in serum as well as in kidney. However, the percentage of heavy
IgA (probably
polymeric IgA) in kidney were, in each patient, higher than those observed in serum. Our results show the presence of high amounts of monomeric and
polymeric IgA, both partially as
immune complexes, in serum and kidneys of patients with
alcoholic liver disease and
IgA glomerulonephritis. Furthermore, our data suggest a role for human liver in the clearance of serum
IgA such as has been demonstrated in the some animal species, especially in rats.