Characterization of the glomerular antibody in acute poststreptococcal glomerulonephritis.

Glomerular-fixed antibody was eluted from the kidney of a 17-year-old patient who died 2 weeks after the onset of acute poststreptococcal glomerulonephritis. Elevated titers of antibodies to streptococcal enzymes were found in the serum but not in the glomerular eluate. Streptococcal M protein and anti-M protein reactivity were not detected in the eluate. Immunoglobulin G was the only serum protein demonstrated in the eluate, and it was found to have anti-IgG activity highly concentrated with respect to the serum. These studies appear to indicate that anti-IgG is involved in the immune pathogenesis of acute poststreptococcal glomerulonephritis. Native IgG may be rendered autoimmunogenic by the streptococcus with subsequent antibody production to the neoautoimmunogen. Alernatively, anti-IgG may be produced to the IgG incorporated in an exogenous streptococcal antigen-antibody complex.