IgG, IgA and IgM rheumatoid factors in patients with glomerulonephritis.

Rheumatoid factors (RF), autoantibodies to IgG, have been postulated to have some pathogenetic role in the development of some types of glomerulonephritis. A simple and sensitive solid-phase fluorescence immunoassay was employed to determine whether IgG, IgA and IgM RF were detectable in sera from patients with various types of glomerulonephritis, rheumatoid arthritis (RA) and those with various streptococcal infections. IgG, IgA and IgM RF were significantly increased in the majority of patients with RA, lupus nephritis (SLE), acute poststreptococcal glomerulonephritis (APSGN) and various streptococcal infections. The titers of IgG and IgA RF were significantly higher in patients with APSGN than in those with simple pharyngitis. IgM RF was increated in patients with IgA nephropathy (IgA-N) and in those with membranoproliferative glomerulonephritis type I (MPGN). No significantly high RF was observed in membranous nephropathy (MN) or chronic mesangial proliferative glomerulonephritis without IgA deposition (PGN). It is suggested that some autologous immune mechanisms may be involved in the pathogenesis of some types of glomerulonephritis.