IgA red cell autoantibodies and autoimmune hemolysis

Abstract

Autoimmune hemolysis due to IgA antibodies alone in rare, with red cell destruction occurring through mechanisms similar to those for IgG. Most commonly, IgA acts synergistically with other immunoglobulins (usually IgG) and complement; the hemolysis may be severe. Whether IgA autoantibodies alone can activate complement remains controversial, but increasing evidence suggests that they can, possibly via the alternative pathway, and that this activation may result in intravascular hemolysis.

Warm Autoimmune Hemolytic Anemia: Clinical Profile and Management

“…Autoimmune diseases, particularly SLE, account for a considerable proportion of secondary WAIHA cases. IgA class antibodies are present in about 14% of patients with WAIHA and almost always occur associated with IgG or IgM [44,45]. Immunotherapy is defined as "the treatment of disease by inducing, enhancing, or suppressing an immune response".…”

IgA-mediated human autoimmune hemolytic anemia as a result of hemagglutination in the spleen, but independent of complement activation and FcαRI

“…1,[4][5][6][7][8] Some of the features of these reported cases, including disease severity, high binding potency of IgA for RBCs with very little free antibody detectable in the serum, no strong evidence of blood group specificity, and in some cases, refractoriness to first-line treatment (administration of high doses of glucocorticosteroids), seem to be characteristic. 1 IgA antibodies exist in several forms, monomeric IgA, dimeric IgA, and polymeric IgA, all of which interact to some extent with the human IgA Fc receptor (Fc␣RI/CD89). 9 The distribution of polymeric and monomeric forms of IgA in the serum differs between species.…”

“…IgA class antibodies are present in approximately 14% of patients with warm-type autoimmune hemolytic anemia (wAIHA) and are almost always associated with IgG or IgM. 1,2 In these cases, warm IgA autoantibodies (optimal reaction at 37°C) generally have a specificity spectrum similar to that of warm IgG autoantibodies. 3 However, wAIHA associated exclusively with IgA antibodies, reacting optimally at 37°C, remains rare.…”

Autoimmune Hemolytic Anemia Predominantly Associated with IgA Anti-E and Anti-c

“…Although only IgA was found in 0.8-2.0% of AIHA (10), the 14% of IgA autoantibodies was reported in the warmtype AIHA, such as IgG+IgA (5.8%), and IgG+IgM+IgA (8%) using sensitive enzyme-treated DAT (2). The presence of more than one type of antibodies on RBCs, even when undetected by agglutination methods, has been reported to be the major cause of hemolysis along with other factors, such as the quantity of bound IgG, the IgG subclass pattern, and complement (2,11). IgA acts synergistically with other immunoglobulins, usually IgG.…”