Anti‐IFC antibodies in a patient with CHAPLE syndrome: Implications for blood management

CHAPLE syndrome is an extremely rare autosomal recessive condition hallmarked by a complete loss of the CD55 protein, hyperactivation of complement, angiopathic thrombosis and protein-losing enteropathy based on primary lymphangiectasia.1 The mechanism behind this syndrome is believed to reside in the fact that CD55, also known as the decay accelerating factor, mitigates complement activation and thus modulates the immune response.1, 2 Importantly, the CD55 protein harbours the entire Cromer blood group system and patients with CHAPLE syndrome characteristically produce antibodies against these antigens when exposed to red blood cells (RBCs) from CD55+ individuals.3-5 The clinical characteristics of these antibodies have not been well documented and are thus largely unclear. We describe the laboratory and clinical effects of anti-IFC antibodies in a 19-year-old female with CHAPLE syndrome and a medical history of liver cirrhosis due to the Budd–Chiari syndrome. The medical history and clinical spectrum of this patient were previously outlined in detail by Ozen et al.,1 as case 8.1. In the years thereafter, the diagnosis and progression of several hepatocellular carcinoma lesions prompted the initiation of the first documented orthotopic liver transplantation (OLT) procedure performed in a patient with CHAPLE syndrome. Due to the likely scenario that the Budd–Chiari-induced portal hypertension would necessitate perioperative blood transfusion and the limited availability of clinical data regarding anti-IFC antibodies, we utilised this unique opportunity to investigate the in vivo potential of the antibodies of causing a haemolytic transfusion reaction. To this end, the patient was subjected to a controlled test transfusion of CD55+ donor RBCs. Informed consent and approval of the Institutional Review Board were obtained. The RBCs were matched for the most frequent clinically relevant blood group antigens, to minimise the risk of further alloimmunisation. From an allogenic CD55+ donor RBC unit containing 6.7 × 1012 RBCs/L, 100 ml blood was infused at a constant rate over a period of 60 min. Subsequently, blood was sampled at various time points as shown in Figure 1. The transfusion was preceded by administration of 0.4 g/kg intravenous immunoglobulin and 100 mg hydrocortisone, in accordance with the recommendation of the International Blood Group Reference Laboratory and existing literature.6 RBC-bound antibodies were detected using monospecific direct antiglobulin tests (DATs) and further investigated in RBC eluates, which were prepared using the commercially available DiaCidel method (Biorad). The kinetics of the administered CD55+ donor RBCs were assessed by means of flow cytometry (BD Biosciences). Routine haemocytometry and chemistry analyses were performed on an XN-10 (Sysmex Corp.) and Cobas 8000 (Roche Diagnostics) analyser, respectively. The calculations of CD55+ donor RBC-recoveries were based on an estimated whole blood volume of 3.77 L, as derived from the Nadler equation,7 a haematocrit of 0.284 L/L and a mean corpuscular volume of 95 fl. Baseline laboratory parameters at start of the test transfusion are shown in Table 1. Despite a haptoglobin concentration below the detection limit, the free haemoglobin concentration in plasma was low at 1 μmol/L and the DAT and RBC eluate were negative. In the circulation, the donor RBCs were well distinguishable from patient RBCs based on CD55-expression and binding of human IgG antibodies (Figure S1). Our data revealed that elimination of the CD55+ donor RBCs started within 20 min after transfusion, as indicated by the divergence of the calculated and measured recoveries (Figure 1). The theoretical maximum recovery was 4.7%, which should have been reached at the end of the test transfusion, i.e., 1 h after the start of the transfusion. However, the actual maximum recovery at that time-point was 1.4%. Albeit the DAT remained negative throughout follow-up, the more sensitive eluate testing of the membrane-bound antibodies showed a reaction pattern that corresponded with that of anti-IFC antibodies (Figure 1). In vivo elimination of the CD55+ donor RBCs was almost complete after 2 h. Total and direct bilirubin, as parameters of haemoglobin degradation, started to increase 1 h after transfusion and peaked ~4 h after transfusion, at concentrations more than double that of baseline values (Figure 1). Conversely, plasma free haemoglobin and indirect bilirubin remained low, indicating that CD55+ donor RBCs were eliminated predominantly through extravascular haemolysis. The positive acute phase proteins complement factors C3 and C4 and C-reactive protein showed a coinciding increase, suggesting that the elimination of the CD55+ donor RBCs was followed by an acute phase response. Despite the acute phase response, no noticeable haemodynamic effects or other clinical signs of a transfusion reaction occurred in the 48 h after the test transfusion. During OLT, three autologous blood units were administered without complications. Following the OLT, the antibody screening was negative for at least 6 consecutive days, suggesting that the anti-IFC antibodies had been transiently removed from the circulation by the liver graft (Figure S2). The main limitation of this study is that conclusions and recommendations are based on a single patient with congenital CD55 deficiency. It is possible that anti-IFC antibodies vary between patients in their potential of causing a haemolytic transfusion reaction. This could for example hold true in patients with a transient evanescence of CD55 expression and production of anti-IFC antibodies.8 Furthermore, it should be emphasised that the transfusion reaction described in this report, was observed under an immunosuppressive and immune modulatory therapeutic regimen, which may have affected the clearance mechanism and efficiency of the anti-IFC antibodies.6, 9 Nevertheless, due to the extensive clinical implications of our findings and the scarcity of other known clinical data, clinicians should strive to avoid transfusion of IFC-incompatible blood in patients with CHAPLE syndrome, irrespective of the presence of anti-IFC antibodies. A second, minor, limitation was the preclusion of the use of haptoglobin as a marker of haemolysis, due to the fact that its concentration was already below the detection limit at the start of the test transfusion. In conclusion, anti-IFC antibodies are capable of inducing an acute extravascular haemolytic transfusion reaction and IFC-compatible blood should be strongly considered for elective blood transfusion in patients with CHAPLE syndrome. As CD55− allogenic blood is unavailable globally, it is imperative that these patients build an adequate blood supply through either CD55-compatible family members or autologous blood donation whenever their clinical situation permits. Isidor Minović performed the research, analysed the data, and drafted the paper; Martin R. Schipperus, Anja B. U. Mäkelburg, Kornelis Meijer, Michaël V. Lukens, Frans van der Heide, Ilhama Abbasova, Jenny E. Kootstra-Ros, Johan H. Meekers, and André B. Mulder designed the study and critically revised the manuscript; Jenny E. Kootstra-Ros, Johan H. Meekers, and André B. Mulder contributed the reagents for the chemistry, immunohematology, and flow cytometry analyses. The authors would like to thank Dr. K. M. K. de Vooght for her valuable assistance in the coordination of blood samples, Dr. H. L. Laevis for her contribution in the patient's care towards liver transplantation, all technicians of the Blood Transfusion Laboratory of the University Medical Center Groningen for their dedication in the measurements of the antibody titres and G. Postema for performing the flow cytometry analyses. Figure S1 Figure S2 Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.