title: Evidence of an autologous immune complex pathogenic mechanism in acute poststreptococcal glomerulonephritis.
abstract: Clinical and experimental studies have suggested a role for antiimmunoglobulins in the pathogenesis of glomerulonephritis associated with streptococcal infection. We attempted to localize anti-IgG in the kidneys of 22 patients who had renal biopsies performed 7 to 66 days after the onset of acute poststreptococcal glomerulonephritis (APSGN). In addition to routine localization of immunoglobulins and C3, specimens were stained with neuraminidase-treated, heat-aggregated, and unmodified IgG. Twelve biopsies showed staining with fluorescein-labeled human neuraminidase-treated IgG. A lesser number gave positive staining with the other IgG preparations. Following treatment of slides with 0.01 M citrate buffer, seven previously negative biopsies showed positive staining with neuraminidase-treated IgG. The demonstration of anti-IgG by these methods was possible in 19 out of 22 biopsies. It correlated best with the presence of C3 and IgG, and to a lesser extent with IgM, in the renal glomerulus. These results and our previous finding of elevated levels of serum anti-IgG early in the course of APSGN, and as early as 8 days following the antecedent streptococcal infection, support a role for anti-IgG in the immune pathogenesis of APSGN. Although our series of studies support the hypothesis that anti-IgG is formed to an IgG modified enzymatically by streptococcal product, the formation of this autoantibody to IgG incorporated in an exogenous (streptococcal antigen-antibody) complex can not be ruled out.
mesh_terms: D000293:Adolescent; D000936:Antigen-Antibody Complex; D001323:Autoantibodies / Q000276:immunology*; D001485:Basement Membrane / Q000276:immunology; D002648:Child; D002675:Child, Preschool; D003176:Complement C3 / Q000032:analysis; D005260:Female; D005452:Fluoresceins; D005921:Glomerulonephritis / Q000209:etiology* / Q000276:immunology; D006801:Humans; D007074:Immunoglobulin G / Q000032:analysis; D007075:Immunoglobulin M / Q000032:analysis; D007678:Kidney Glomerulus / Q000276:immunology; D008297:Male; D013290:Streptococcal Infections / Q000150:complications* / Q000276:immunology; D013997:Time Factors
chemical_list: D000936:Antigen-Antibody Complex; D001323:Autoantibodies; D003176:Complement C3; D005452:Fluoresceins; D007074:Immunoglobulin G; D007075:Immunoglobulin M