Complexes of IgA with FcalphaRI/CD89 are not specific for primary IgA nephropathy

Kidney Int. 2003 Feb;63(2):514-21. doi: 10.1046/j.1523-1755.2003.00756.x.


Background: The presence of IgA together with the myeloid IgA-receptor FcalphaRI/CD89 in the circulation of patients with IgA nephropathy (IgAN) has been suggested as a specific pathogenic factor for mesangial deposition. However, in a recent study we found these complexes also in serum samples from healthy subjects. To investigate whether these circulating complexes are specific for IgAN, the levels and characteristics of IgA-CD89 complexes were analyzed in patients with IgAN and healthy controls.

Methods: Specific ELISAs with different poly- and monoclonal antibodies and a sensitive dot-blot method were used to measure IgA-CD89 levels in serum and purified IgA samples obtained from healthy volunteers (N = 30) and patients with IgAN (N = 35). Fractionated samples of purified IgA were used to compare the size characteristics of the IgA-CD89 complexes.

Results: Almost all CD89 in serum of patients with IgAN and controls was associated with high molecular weight IgA. Quantitative analysis of IgA-CD89 complexes in purified IgA revealed no significant difference between patients with IgAN and controls. No correlation was found between levels of IgA-CD89 complexes and clinical parameters associated with progressive IgAN.

Conclusions: CD89 in the circulation is found mainly linked to high molecular weight IgA. The presence of these complexes is not specific for IgAN. Therefore, if IgA-CD89 complexes are involved in the pathogenesis of primary IgA nephropathy, additional factors are required to explain the IgA-CD89 complex-mediated renal inflammation.

MeSH terms

  • Adult
  • Antigens, CD / blood*
  • Antigens, CD / isolation & purification
  • Case-Control Studies
  • Chemical Fractionation
  • Enzyme-Linked Immunosorbent Assay / methods
  • Glomerulonephritis, IGA / blood*
  • Humans
  • Immunoglobulin A / blood*
  • Immunoglobulin A / chemistry
  • Immunoglobulin A / isolation & purification
  • Male
  • Middle Aged
  • Molecular Weight
  • Receptors, Fc / blood*
  • Receptors, Fc / isolation & purification


  • Antigens, CD
  • Fc(alpha) receptor
  • Immunoglobulin A
  • Receptors, Fc