Effects of complement inactivation and IgG depletion on skin reactivity to autologous serum in chronic idiopathic urticaria

J Allergy Clin Immunol. 2000 Sep;106(3):567-72. doi: 10.1067/mai.2000.108913.


Background: Intradermal injection of autologous serum elicits a wheal-and-flare response in about 60% of patients with chronic idiopathic urticaria (CIU). This reactivity has been attributed to the presence of IgG autoantibodies directed against IgE or the alpha-chain of the high-affinity IgE receptor (FcepsilonRIalpha) expressed on basophils and mast cells, leading to the hypothesis that at least some forms of CIU could be sustained by an autoimmune process.

Objectives: The aim of this study was to investigate the relationship between the presence of anti-IgE or anti-FcepsilonRI antibodies and the ability to induce wheal-and-flare responses in CIU sera selected for the capacity to give a positive skin test response.

Methods: Fifteen patients with CIU and a positive skin test response to autologous serum were injected intradermally with native serum and with serum heated at 56 degrees C for 30 minutes and then adsorbed on Sepharose-protein G to obtain IgG depletion. Serum levels of anti-IgE and anti-FcepsilonRIalpha antibodies were measured by ELISA by using purified IgE and recombinant RIalpha-soluble double-fusion protein RIalpha-human serum albumin-RIalpha, respectively. The histamine-releasing activity of sera was tested by using ELISA with whole human blood from a healthy donor.

Results: All patients had positive cutaneous responses to native serum injection. Anti-FcepsilonRIalpha antibodies were present in 14 of 15 native sera, only two of which were able to induce in vitro basophil degranulation. On the contrary, detectable amounts of anti-IgE antibodies were not found in any serum. IgG depletion by protein G resulted in complete (10/14 samples) or considerable (4/14 samples) removal of anti-FcepsilonRIalpha antibodies. The two sera endowed with functional activity lost their capacity to trigger histamine release from basophils after heating and protein G adsorption. Nonetheless, heat-decomplemented/IgG-depleted sera elicited wheal-and-flare reactions comparable with those observed with untreated sera.

Conclusions: These results strongly suggest that skin reactivity to autologous serum could be due to as yet unidentified non-Ig reactants present in the sera of patients with CIU.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Antibodies / blood
  • Antibodies, Anti-Idiotypic / blood
  • Antibodies, Anti-Idiotypic / immunology
  • Autoantibodies / blood
  • Chronic Disease
  • Complement Inactivator Proteins / pharmacology*
  • Female
  • Histamine / blood
  • Humans
  • Immunoglobulin G / physiology*
  • Male
  • Middle Aged
  • Receptors, IgE / immunology
  • Skin / immunology*
  • Skin Tests
  • Urticaria / blood*
  • Urticaria / etiology


  • Antibodies
  • Antibodies, Anti-Idiotypic
  • Autoantibodies
  • Complement Inactivator Proteins
  • Immunoglobulin G
  • Receptors, IgE
  • anti-IgE antibodies
  • Histamine