Autoimmune hemolytic anemia predominantly associated with IgA anti-E and anti-c

Primary IgA-mediated Autoimmune Hemolytic Anemia in an Infant Successfully Treated With Rituximab

Autoimmune hemolytic anemia (AIHA) is uncommon in the pediatric population and is often associated with an infectious etiology or postvaccination. Mostly, the child presents with a positive direct antiglobulin test. The diagnosis can be challenging, as in our case with an immunoglobulin A-mediated AIHA. In addition to supportive therapy, such as a red blood cell transfusion, steroids are the first choice of treatment. Rituximab, as second-line treatment, can be given in conjunction. We report the first case of immunoglobulin A-mediated AIHA treated with rituximab in the literature.

IgA-mediated autoimmune hemolytic anemia in an infant

Autoimmune Hemolytic anemia (AIHA) a relatively uncommon form of hemolytic anemia in children, occurs due to the premature destruction of red blood cells caused by presence of autoantibodies directed against antigens on RBCs. Warm reactive AIHA is the most common form due to IgG isotype of immunoglobulin class binding to autologous RBCs at 37⁰C and confirmed with a positive DAT screening. We present a case of DAT-negative primary warm AIHA in an infant due to IgA antibody. A 10 month old male infant presented with dark colored urine and irritability for past two months, with associated history of fever, diarrhea and vomiting. He had received one red cell transfusion 10 days prior. On physical examination he had pallor with tachycardia without splenomegaly. On investigation his hemoglobin was 5.8 g/dl, WBC 25.9 × 10³/mm³ and normal platelets counts. Peripheral blood smear had spherocytes and biochemical values showed high bilirubin and LDH. Immunohematological work up revelaed polyspecific DAT was negative but monospecific DAT screening showed strong (4+) positivity for IgA and a weak IgG positivity. The patient was diagnosed as IgA-mediated Warm AIHA and was started on prednisolone at 2 mg/kg/day following which hemoglobin improved over the next 2 months. After 2 weeks, prednisolone was tapered and stopped by the end of 3 months. Patients with clinical and laboratory evidence of acute hemolysis, an additional screening for IgA antibody may be done even in cases where poly-specific DAT is negative. Early detection helps in avoiding further investigations and provide efficient management.

Severe Autoimmune Hemolytic Anemia in an Infant Caused by Warm-reactive IGM and IGA Autoantibodies: A Case Report and Review of the Literature

Warm-reactive IgM autoimmune hemolytic anemia is uncommon and carries a poor prognosis in adults. There have been rare reports in children, generally associated with an underlying immunologic deficiency, and outcomes are quite variable. Warm IgM in combination with other antibodies has not been reported in children. We report the first case of severe, steroid-responsive autoimmune hemolytic anemia caused by both warm-reactive IgM and IgA autoantibodies in an otherwise healthy 3-month-old.

Clinical features and outcomes of autoimmune hemolytic anemia: a retrospective analysis of 32 cases

Background

There has been no report on the clinical features or natural history of autoimmune hemolytic anemia (AIHA) in the Korean adult population. This study retrospectively analyzed the clinical characteristics and long-term outcomes of AIHA in the Korean adults.

Methods

Patients newly diagnosed with AIHA between January 1994 and December 2010 at Chungnam National University Hospital were enrolled. Patient characteristics at diagnosis, response to treatment, and the natural course of the disease were documented.

Results

Thirty-two patients (31 females and 1 male) with a median age of 48 years (range, 17-86) were enrolled. Of these, 21.9% were initially diagnosed with secondary AIHA. Thirteen patients (40.6%) were initially diagnosed with Evans' syndrome. Of the 29 patients who were placed on therapy, 27 (93.1%) showed a partial response or better. Nevertheless, 1 year after initiating treatment, 80% of the patients were still treatment-dependent. During follow-up (median length 14 months; range, 0.5-238), 14 of 25 patients (56.0%) who were initially diagnosed with primary warm antibody AIHA were found to have systemic lupus erythematosus (SLE). Median time to conversion to SLE was 8.0 months (95% CI, 4.3-11.7), and the probabilities of conversion at 12 and 24 months were 63% and 91%, respectively. Younger age (<60 years) and a positive fluorescent anti-nuclear antibody test were associated with a higher probability of SLE conversion (P=0.01 and P<0.001, respectively).

Conclusion

Primary AIHA is rare. Regular, vigilant testing for SLE is required in patients initially diagnosed with AIHA.

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

Autoimmune hemolytic anemia (AIHA) due to warm-acting IgA autoantibodies is rare. We explored the pathogenic mechanisms underlying destruction of red blood cells (RBCs) in a patient with severe AIHA mediated exclusively by polymeric immunoglobulin A (pIgA) anti-Band 3 autoantibodies. The follow-up period was 17 months. RBCs were not destroyed by complement activation as no deposition of complement was observed on the patient's RBCs. pIgA eluted from the patient's RBCs did not induce RBC destruction through phagocytosis by monocytes or antibody-dependent cell-mediated cytotoxicity by natural killer cells. Induction of eryptosis (ie, RBC apoptosis) due to direct alteration of the RBC membrane by pIgA autoantibodies was also excluded. By contrast, upon incubation with pIgA-opsonized RBCs, substantial RBC membrane transfers (ie, trogocytosis) to monocytes were observed that might contribute to RBC immune destruction. This effect was poorly inhibited by blockers of Fc receptors, excluding a major contribution of FcαRI to this process. Histologic analysis revealed a massive accumulation of agglutinated RBCs with little sign of erythrophagocytosis in the spleen. These results, together with the efficacy of splenectomy 17 months after AIHA onset, suggest that the trapping and subsequent sequestration of agglutinated RBCs in the spleen are the principal pathogenic mechanisms of pIgA-mediated AIHA.