Atypical presentation of acute phase, antibody‐induced haemolytic anaemia in an infant

Abstract

We describe a case of 'warm' antibody-induced haemolytic anaemia (WAIHA) in which marked depression of red cell Rh antigen expression resulted in the patient presenting with severe anaemia but a negative direct antiglobulin test (DAT). The serum contained potent IgG Rh antibodies. Unlike two previously reported cases (Koscielak, 1980; Veer et al. 1981) in which the diagnosis of WAIHA was established before the DAT became negative, this patient presented with negative serological findings during his first episode of anaemia. As a result, the serum antibodies appeared to be allo- not autoimmune in nature and to be unrelated to the patient's anaemia. Confirmation of the autoimmune nature of the Rh antibodies was not possible until nearly 2 years after the first episode of anaemia.

Nonhemolytic antibody-induced loss of erythrocyte surface antigen

“…Suppression of blood group antigens has most often been documented in the setting of AIHA. [1][2][3][4][5][6][7][8][9][10][11][12][13] The precise frequency of antigen suppression in AIHA is uncertain, but approximately 10% of patients with AIHA have a negative DAT. Although the percentage of patients with DATnegative AIHA who have antigen suppression is unknown, the frequency of antigen suppression in AIHA may be significant.…”

“…by guest www.bloodjournal.org From a patient with an alloantibody against a clinically significant antigen, such as Rh, Kell, Kidd, or Duffy. However, antigens in each of these blood group systems have also been shown to be capable of undergoing a process of antigen suppression in the setting of autoantibodies, [1][2][3][4][5][6][7][8][9][10][11][12][13] and antigen suppression on transfused RBCs has been confirmed in the case of several alloantibodies. 2,3 In the rare cases that crossmatchincompatible transfusions are given, either as a "least incompatible" unit or due to a clerical error, a progressive decrease in DAT is interpreted as antibody-mediated destruction of the transfused RBCs.…”

“…However, some RBCs can escape antibody-mediated hemolysis through selective loss of the antigen recognized by alloantibodies or autoantibodies. "Antigen suppression" of this type has most often been observed with Kell blood group antigens, [1][2][3][4][5][6][7][8] but the phenomenon has also been reported with Rh (including D and e), 9,10 Kidd, 11,12 Duffy, 13 Lutheran, 3 and other blood group antigens such as LW, Co, Ge, En a , AnWj, and Sc1. 13 When suppression of antigen occurs, patient specimens test negative by the direct antiglobulin test (DAT), which measures the presence of antibody on the surface of RBCs by incubating RBCs with anti-human immunoglobulin (Ig).…”

IgG-Mediated Immune Suppression to Erythrocytes by Polyclonal Antibodies Can Occur in the Absence of Activating or Inhibitory Fcγ Receptors in a Full Mouse Model

“…Although Ag loss has been reported involving Abs against several different blood group Ags (60)(61)(62)(63)(64)(65), there is little understanding of this phenomenon or its contribution to IgG-mediated suppression. Studies in animal models have shown that it requires the binding of multiple Abs to the RBC, and individual monoclonal Abs did not induce Ag loss (59).…”

Nonhemolytic antigen loss from red blood cells requires cooperative binding of multiple antibodies recognizing different epitopes

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] This phenomenon has been reported involving antibodies against several different blood group antigens, including single-pass transmembrane proteins (Kell and Kidd) and multipass transmembrane proteins (Duffy and Rh). [1][2][3][4][5][6][7][8][9][10][11][12][13][14] Western blot analysis of human RBCs that have undergone antigen loss suggest that for at least one case of antigen loss in the Kell system, the entire protein that carries the blood group antigen is removed from the RBC, as opposed to just a destruction of the part of the molecule that constitutes the antigen. 4 Although antigen loss has been described in multiple case reports, there is little mechanistic understanding of this phenomenon.…”