Serum and glomerular IgG in poststreptococcal glomerulonephritis are correlated

Among 75 patients hospitalized for poststreptococcal acute glomerulonephritis, 33 (44%) had an elevated serum level of IgG. The IgA level was elevated in 11 of 39 patients (28%). Paradoxically, of 20 biopsied patients with elevated IgG levels, IgG was absent from the glomerular deposits in 11, while of 23 with normal IgG levels, IgG was absent from the glomerular deposits in only 2 (P <0.001). Also, patients with an elevated level more frequently had antistreptolysin O titers > or =833 Todd units (P < 0.001). Elevated IgG did not correlate with severity of disease, with age of the patient, or with the serum albumin or C3 level. There appears to be a subset of patients with elevated serum IgG levels who with high frequency have IgG absent from their glomerular deposits. Thus, failure to form antibody to a glomerular-bound protein produced by the nephritogenic streptococcus, widely assumed to be the origin of the IgG in the glomerular deposits, is in some way significantly associated with elevated serum levels of IgG and of antibody to streptolysin O.