Galactose-deficient IgA1 in sera of IgA nephropathy patients is present in complexes with IgG

Kidney Int. 1997 Aug;52(2):509-16. doi: 10.1038/ki.1997.361.


IgA1 proteins from sera of patients with IgA nephropathy (IgAN) are galactosylated to a lesser degree than those from healthy controls. The increased reactivity of intact or de-sialylated serum IgA1 with N-acetylgalactosamine (GalNAc)-specific lectins, Helix aspersa (HAA) and Caragana arborescens (CAA) and de-sialylated IgA1 with Helix pomatia (HPA) and Bauhinia purpurea (BPA) indicated that the Gal deficiency is in glycans located in the hinge region of IgA1 molecules. De-sialylated IgA from sera of 81 IgAN patients bound biotin-labeled lectin HAA more effectively than did de-sialylated IgA from 56 healthy controls (P < 0.0001). Similar results were observed for 67 IgAN patients and 52 controls with second lectin, CAA (P < 0.001). The binding patterns for 9 patients with mesangial proliferative glomerulonephritis of non-IgA origin were similar to those for controls. Incompletely galactosylated IgA1 capable of binding GalNAc-specific lectins was detected in complexes with IgG as demonstrated by ELISA, size-exclusion chromatography and sucrose gradient ultracentrifugation. The formation of IgA1-IgG complexes may affect the serum level of IgA1 by reducing the rate of its elimination and catabolic degradation by the liver.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Carbohydrate Sequence
  • Chromatography, High Pressure Liquid
  • Female
  • Galactose / chemistry
  • Galactose / deficiency*
  • Glomerulonephritis, IGA / blood*
  • Glomerulonephritis, IGA / immunology
  • Humans
  • Immunoglobulin A / blood*
  • Immunoglobulin A / chemistry
  • Immunoglobulin A / immunology
  • Immunoglobulin G / immunology
  • Immunoglobulin G / metabolism*
  • Immunoglobulin M / metabolism
  • Lectins
  • Male
  • Middle Aged
  • Molecular Sequence Data
  • Proteoglycans / chemistry
  • Proteoglycans / metabolism


  • Immunoglobulin A
  • Immunoglobulin G
  • Immunoglobulin M
  • Lectins
  • Proteoglycans
  • Galactose