The importance of serum immunoglobulin levels and IgG subclass composition of circulating immune complexes in patients with post-streptococcal glomerulonephritis - abstract

ABSTRACT

Immunoglobulin levels, circulating immune complexes and IgG subclasses in the immune complexes were studied in sera from 34 patients with post-streptococcal acute glomerulonephritis (PSAGN). Serum IgG levels were depressed in 91 percent of PSAGN patients while serum IgA (82 percent) and IgM (97 percent) levels were elevated when compared with the mean values for 106 children all under 10 years of age. Circulating immune complexes were prepared by the 3 percent polyethylene glycol (PEG) 6,000 precipitation method and IgG- and IgM-containing immune complexes of PSAGN patients were elevated compared with those of controls. No IgA-containing complexes were seen in these patients. IgG-complexes returned to normal levels within 3-6 months after onset. In contrast, IgM-contain complexes, which were heightened at onset of illness, remained elevated even after six months. Subclass determinations of circulating IgG-containing immune complexes from PSAGN patients showed that IgGl and IgG2 were predominant while IgG3 was much reduced. IgGl-, IgG2- and IgG3- containing complexes returned to normal values within 3 months, but IgG2 complexes appeared to rise again at 6 months. IgG3-containing immune complexes appear to initiate glomerular injury in PSAGN patients whereas IgG2- containing immune complexes may be implicated in long-term glomerulonephritis (AU)