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Detection of red blood cell antibodies in mitogen‐stimulated cultures from patients with hereditary spherocytosis
Author(s) -
Zanii Anna,
Vercellati Cristina,
Imperiali Francesca G.,
Marcello Anna P.,
Fattizzo Bruno,
Fermo Elisa,
Bianchi Paola,
Grossi Claudia,
Cattaneo Alessandra,
Cortelezzi Agostino,
Zanella Alberto,
Barcellini Wilma
Publication year - 2015
Publication title -
transfusion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.045
H-Index - 132
eISSN - 1537-2995
pISSN - 0041-1132
DOI - 10.1111/trf.13257
Subject(s) - hereditary spherocytosis , antibody , red blood cell , medicine , spherocytosis , immunology , splenectomy , spleen
BACKGROUND Hereditary spherocytosis (HS) is a congenital hemolytic anemia caused by defects in red blood cell (RBC) membrane proteins leading to premature RBC clearance in the spleen. The presence of RBC autoantibodies has never been extensively investigated in HS. STUDY DESIGN AND METHODS RBC antibody–bound immunoglobulin (Ig)G was investigated in 91 consecutive HS patients by mitogen‐stimulated direct antiglobulin test (MS‐DAT), a sensitive method able to magnify latent RBC antibody autoimmunity and related with hemolytic variables, previous splenectomy, and type of membrane defect. RESULTS A total of 61% of HS cases had RBC antibodies by MS‐DAT (29 Band 3, 17 spectrin deficiency, and nine no defined defect). The amount of RBC‐bound IgG was greater in HS compared with controls (236 ± 192 ng/mL vs. 52 ± 29 ng/mL, p < 0.0001), although lower than that observed in autoimmune hemolytic anemia (AIHA; 634 ± 371 ng/mL vs. 236 ± 192 ng/mL, p < 0.0001). Western blot experiments showed that purified IgG fraction from MS‐DAT–positive patients bind to α‐ and β‐spectrin, Band 3, and Band 4.9. Positive cases displayed increased reticulocytosis and slightly reduced hemoglobin (Hb) values compared to negative ones. Patients displaying RBC‐bound IgG of more than 250 ng/mL (the positive threshold of AIHA) showed increased number of spherocytes and mainly had spectrin deficiency. RBC‐bound IgG and free Hb increased over time after storage at 4°C, a surrogate of ex vivo aging, more evidently in HS than controls, and particularly in Band 3 deficiency. CONCLUSION RBC autoantibodies were detected by MS‐DAT in more than a half of HS patients. Positive cases showed a more evident hemolytic pattern suggesting a pathogenic role of these autoantibodies in RBC opsonization and splenic removal.