Immunofluorescence patterns in chronic membranoproliferative glomerulonephritis (MPGN).

90 patients, whose renal biopsies showed on light microscopy a pattern of MPGN, have been studied by immunofluorescence. 10 cases showed dense intramembranous deposits. Fluoresceinated antisera against IgG, IgA, IgM, C3, fibrinogen, IgD, IgE, C4, C1q, properdin and C3A were employed. Granular depostis of C3 were observed in all cases; IgG, IgM, properdin, C1q and C4 were found in 2/3 cases; IgA, IgE and C3A were rarely found. The localization of these deposits was parietal and often also mesangial. On the basis of glomerular deposition of C3 with or without immunoglobulins (Ig), we separated the cases into three groups: 1) C3 + Ig (59 cases), 2) predominant C3 (19 cases), 3) isolated C3 (12 cases). Most patients with dense deposits disease were classified in the third group. Deposits of C1q and C4 were found only in the first two groups. The localization of C3 deposits showed a more frequent mesangial extension in the second and third groups. Patients in these 3 groups also had different serum complement profiles. No significant differences in the major clinical features could be found in the 3 groups. Variable immunofluorescence patterns, in agreement with other serological parameters, confirm the heterogeneity of pathogenetic mechanisms in patients with MPGN.