de Boer Esther C W, Mulder Femke V M, Neri Silvia, Wiskerke-van Stuijvenberg Marije, Arts Janine J G, Tol Simon, Beuger Boukje, Bosman Matthieu C J, Thielen Noortje, van der Griend René, Folman Claudia C, de Haas Masja, van Bruggen Robin, Pouw Richard B, Vos Josephine M I
Sanquin Research and Landsteiner Laboratory of the Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, The Netherlands.
Department of Pediatric Immunology, Rheumatology, and Infectious Diseases, Emma Children's Hospital, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands.
Transfusion. 2025 Jun;65(6):1132-1144. doi: 10.1111/trf.18270. Epub 2025 May 12.
Autoimmune hemolytic anemia (AIHA) is typically mediated by immunoglobulin G (IgG) or immunoglobulin M (IgM) antibodies, and more rarely by immunoglobulin A (IgA). The mechanism of red blood cell (RBC) destruction in IgA-mediated AIHA is not well understood. We report a case of severe AIHA with intravascular hemolysis, positive for IgA. Hemolysis did not subside despite multiple transfusions and treatment lines, leading to a fatal outcome. Here, we set out to investigate underlying pathophysiological mechanisms.
To investigate the underlying pathophysiological methods, standard hematological methods were used, as well as erythrophagocytosis assays and flow cytometry using patient RBCs and plasma, to investigate anti-RBC antibodies, complement activation, and vesiculation.
Blood smear analysis revealed significant heterogeneity in RBC size and volume, and the presence of ghost cells, indicating RBC damage. While the patient's RBCs were found opsonized with IgA and IgG autoantibodies, phagocytosis by neutrophils was not induced in vitro, nor did sensitized donor RBCs with patient plasma. Using flow cytometry, we detected vesicles in the patient's plasma and observed patient plasma-induced vesiculation of healthy donor RBC. Patient plasma showed marked complement activation, and the vesicles in the patient plasma were also complement-opsonized, as well as bound by IgA, IgG, and IgM.
Based on these findings, we suggest vesiculation of RBCs as evidenced by the presence of vesicles and ghost cells in the patient, and subsequent complement activation induced by the vesicles. This could have driven the aggravation of the disease in this patient, resulting in a fatal outcome.
自身免疫性溶血性贫血（AIHA）通常由免疫球蛋白G（IgG）或免疫球蛋白M（IgM）抗体介导，很少由免疫球蛋白A（IgA）介导。IgA介导的AIHA中红细胞（RBC）破坏的机制尚不清楚。我们报告一例严重AIHA伴血管内溶血，IgA呈阳性。尽管进行了多次输血和多种治疗，溶血仍未消退，导致了致命的结果。在此，我们着手研究潜在的病理生理机制。
为了研究潜在的病理生理方法，使用了标准血液学方法，以及红细胞吞噬试验和使用患者红细胞和血浆的流式细胞术，以研究抗红细胞抗体、补体激活和囊泡形成。
血涂片分析显示红细胞大小和体积存在显著异质性，且存在影细胞，表明红细胞受损。虽然发现患者的红细胞被IgA和IgG自身抗体调理，但体外未诱导中性粒细胞吞噬，用患者血浆处理的供体致敏红细胞也未出现吞噬现象。使用流式细胞术，我们在患者血浆中检测到囊泡，并观察到患者血浆诱导健康供体红细胞形成囊泡。患者血浆显示出明显的补体激活，患者血浆中的囊泡也被补体调理，同时结合有IgA、IgG和IgM。
基于这些发现，我们认为患者体内存在囊泡和影细胞证明红细胞发生了囊泡形成，随后囊泡诱导了补体激活。这可能导致了该患者病情加重，最终导致致命结果。
