Specificity of eluted antibody from renal tissues of patients with IgA nephropathy.

A study on the specificity of antibodies eluted from renal biopsy specimens in patients with IgA nephropathy is described. Renal biopsy specimens were obtained from patients with IgA nephropathy and other glomerular diseases. These specimens were treated with citrate buffer (pH 3.2) and the "eluate" was neutralized by sodium hydroxide. The "eluate" was then applied to the acid-treated sections obtained from the same and other patients with IgA nephropathy as well as to those with other glomerular diseases. The sections were stained with FITC-labeled heavy-chain-specific anti-human IgA antisera and examined with a fluorescent microscope. It was demonstrated that the antibodies obtained from patients with IgA nephropathy specifically recombined with the glomerular mesangial areas in such patients, while these antibodies did not combine with renal tissues obtained from patients with out IgA nephropathy. The eluted antibodies combined with autologous tissues, but only one-third of them combined with allogeneic renal specimens with IgA nephropathy. It is concluded that IgA antibodies deposited in glomeruli are specific to mesangial areas of patients with IgA nephropathy and that these antibodies show some heterogeneity among patients with this disorder.