Red Cell Autoantibodies

Wilma Barcellini, Alberto Zanella

Research output: Chapter in Book/Report/Conference proceedingChapter


Anti-red blood cell (RBC) autoantibodies are the causative agents of autoimmune hemolytic anemia (AIHA), whose estimated incidence is one to three cases per 100,000 per year. The most frequent are immunoglobulin (Ig)G, which are usually directed against epitopes of the Rh system, react at 37 °C, mainly determine extravascular hemolysis, and are responsible for the ''warm'' forms (WAIHA). IgM are pentameric autoantibodies able to fix complement more efficiently than other isotypes, cause intravascular hemolysis, are directed against the I/i system, have an optimal temperature of reaction at 4 °C, and are responsible for the ''cold'' forms of autoimmune hemolytic anemia (cold hemoagglutinin disease, CHD). AIHAs can be distinguished as primary (idiopathic) and secondary to other diseases (autoimmune, infections, lymphoproliferative, or neoplastic diseases) and show great clinical heterogeneity, from compensated forms without anemia to fulminating disease. The gold standard for the detection of anti-RBC antibodies is the direct antiglobulin test (DAT) or Coombs test. DAT-tube is the traditional agglutination technique usually performed with broad-spectrum Coombs reagents; the use of monospecific anti-IgG, anti-IgM, and anti-C3 antisera is recommended to define the class of the autoantibody, along with its thermal characteristics. It is worth mentioning a simple test, the spontaneous agglutination of RBCs at 20 °C, a characteristic feature indicating the presence of cold IgM autoantibodies. DAT-tube may give false-negative results due to the small number of RBC-bound IgG molecules below the threshold of the test (estimated 400 molecules per RBC). Moreover, the tube technique with polyspecific (IgG+C) may fail to detect IgA autoantibodies; the use of monospecific antisera against IgA can overcome the DAT negativity. Another cause of DAT-negativity may be the presence of low-affinity autoantibodies, which can be detected by low ionic strength solutions (LISS) or cold washings. More sensitive methods include microcolumn, solid-phase, complement-fixation antibody-consumption test, enzyme-linked and radiolabelled tests, flow-cytometry, mitogen-stimulated-DAT, and the dual direct antiglobulin test. Despite all the above-mentioned tests, 5-10% of AIHA may be DAT negative, and the diagnosis is made after exclusion of other causes of hemolysis and on the basis of the clinical response to therapy.

Original languageEnglish
Title of host publicationAutoantibodies: Third Edition
PublisherElsevier B.V.
Number of pages7
ISBN (Print)9780444563781
Publication statusPublished - Dec 2013


  • Anti-red cell autoantibodies
  • Autoimmune hemolytic anemia
  • Cold hemoagglutinin disease
  • Diagnosis
  • Direct antiglobulin test

ASJC Scopus subject areas

  • Immunology and Microbiology(all)


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