Abstract
Objective : IgA nephropathy (IgAN) is the most common chronic glomerulonephritis. Although the glomerular deposition of complement components is well known, evidence of serological complement activation is inconclusive in patients with IgAN. We hypothesized that serum levels of complement components and regulatory proteins in patients with IgAN are correlated with its pathogenesis.
Materials & Methods : In the present study, complement components in 50 patients with IgAN and 50 healthy volunteers were measured. C5, C1 inhibitor, factor B, C4 binding protein, factor H, and factor I levels were measured by single radial immunodiffusion. Mannose-binding lectin and properdin were measured by the enzyme-linked immunosorbent assay. Correlations of complements in serum with clinical gradings for IgAN, i.e., the good prognosis group, relatively good prognosis group, relatively poor prognosis group, and poor prognosis group, were evaluated.
Results : CH50, C4, factor B, properdin, factor I, and factor H levels in IgAN patients were significantly higher than those in healthy controls. There were significant correlations between C4 and C1 inhibitor, and between C5 and C4 binding protein in patients with IgAN. In the poor prognosis group, C4 binding protein was significantly higher than in other groups of IgAN.
Conclusion : In IgAN, hypercomplementemia with increased complement regulatory proteins occurs. C4 binding protein analyses can be used to predict the disease prognosis of IgA nephropathy patients.
