Characterization of red cell autoantibodies in consecutive DAT-positive patients with relation to in vivo haemolysis

Abstract

The clinical symptoms of patients with autoimmune haemolytic anaemia (AIHA) may range from no symptoms at all to severe haemolysis with life-threatening anaemia. The aim of the present study was to characterize the autoantibodies serologically and to evaluate their activity in vitro in monocyte monolayer assay (MMA) in consecutive direct antiglobulin test (DAT)-positive patients from a haematological department. We also aimed to evaluate the monocyte production of cytokines in vitro and relate all findings to in vivo haemolysis. Twenty-nine patients with positive DAT were included in the study and clinical characteristics were documented. The patients were divided into three groups based on laboratory parameters, severe haemolysis, moderate haemolysis and no sign of haemolysis. Severe haemolysis was related to a strongly positive DAT and positive results in MMA. When eluates were analysed in MMA, a positive result was associated with a higher concentration in the supernatants of interleukin (IL)-8 after 6 h incubation. We conclude that MMA activity and in vitro cytokine production may reflect the in vivo activity of autoantibodies. This may be of importance in understanding the mechanisms of haemolysis and in predicting the harmfulness of antibodies, especially when blood transfusions are needed.

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

“…Data from erythrophagocytosis tests are generally strongly correlated with the severity of AIHA involving IgG. 28 Our results differed somewhat from those of a previous study reporting moderate phagocytosis in a case of wAIHA with pure IgA. 14 This discrepancy was not due to the use of monocytes from healthy donors in our study, as similar negative results were obtained during the first few days of the follow-up, in coculture experiments with monocytes and sensitized RBCs obtained from fresh blood samples of the patient (data not shown).…”

The IgG-specific endoglycosidase EndoS inhibits both cellular and complement-mediated autoimmune hemolysis

“…[33][34][35] Therefore, we found it relevant to establish the role of EndoS regarding the in vitro response of monocytes exposed to sensitized RBCs by measuring the release of IL-8. Thus, THP-1 cells and monocytes were incubated with anti-D-sensitized RBCs, and the secretion of IL-8 was measured using ELISA.…”

Autoimmune hemolytic anemia: transfusion challenges and solutions

“…1,5 It has been recommended that compatible blood must be transfused to AIHA patients carrying RBC-specific autoantibodies; however, some authors ignore the specificity of the autoantibody because some reports have not demonstrated significant differences in the survival of antigen-specific compatible RBCs used for transfusion, or have shown that the benefit was minimal. 1,2,17,18 Patients with CAIHA present positive DAT result with anti-C3 or anti-(C3+IgG) reagents but negative with antiIgG reagent. Table 2 summarizes the immunohematological findings in patients with various types of AIHA.…”

“…These symptoms generally occur in patients with very profound anemia showing hemoglobin levels below 5 g/dL (Table 4). 1,6,17,18,28,34 In mild or moderate anemias (Hb>8 g/ dL) RBC transfusion is rarely necessary or desirable, as symptoms generally are controlled with appropriated therapy. For patients showing hemoglobin level between 5 and 8 g/dL the clinical decision for transfusion is more difficult.…”

“…RBC transfusion may be necessary particularly for the symptomatic elderly, for patients with coronary artery disease with increased risk of cardiac or cerebral events, and life-threatening situations related to the anemia. 13,14,[17][18][19][20] First-line treatment of individuals with AIHA consists of glucocorticoids that often results in early improvement of the hemolytic state interrupting the hemoglobin level decrease usually 24-72 hours after therapy has been started. Another possible initial treatment for severe or refractory patients is the use of anti-CD20 monoclonal antibody (rituximab) that may rapidly reduce the hemolysis making RBC transfusion unnecessary.…”