Immune hemolysis after fludarabine-based reduced intensity conditioning and allogeneic PBSC transplantation for CML with minor ABO incompatibility

Abstract

Dear Editor, Fludarabine is commonly used in reduced intensity conditioning (RIC) regimens and has been linked to immune hemolysis [1, 2]. We report the first case of severe immune hemolysis in the fludarabine-based RIC allogeneic peripheral blood stem cell transplantation (PBSCT) for chronic myelogenous leukemia (CML) in the setting of minor ABO incompatibility. A 47-year-old woman diagnosed with CML underwent allo-PBSCTwith an HLA-matched related donor in February 2007, while in the accelerated phase. Conditioning consisted of busulfan, 2 mg/kg/day (days −6 and −5), fludarabine, 30 mg/m2/day (days −6 to −2), and anti-thymoglobulin, 10 mg/kg/day (days −4 to −1). GVHD prophylaxis consisted of cyclosporine, 5 mg/kg/day, and mycophenolate mofetil, 45 mg/kg/day. There was minor ABO incompatibility between the donor (O Rh-positive) and the recipient (B Rhpositive). The donor's anti-B antibody titer in saline test tube at 37°C was 1:8 IgG. The conditioning regimen and stem cell infusion were both uneventful. Eight days after PBSCT, she developed mucocutaneous pallor, asthenia, and nausea. Laboratory studies indicated severe hemolysis with a drop in the hemoglobin level, an increase in the serum bilirubin and lactic dehydrogenase (LDH) levels, and complete disappearance of haptoglobin (graph). Peripheral blood contained spherocytes. No fragmentation was observed. Renal function and clotting studies were normal. Thorough microbiological studies were negative. Investigations for hepatitis A, B, and C viruses, VDRL, HTLV I and II, HIV, HSV, adenovirus, parvovirus, EBV, HHV-6, cytomegalovirus, and toxoplasmosis were negative. Computed tomography (CT) of the chest and sinuses was normal, and CT of the abdomen showed only splenomegaly. Serological screening for autoimmune diseases was negative. None of the medications she was receiving was known to cause hemolysis. The direct antiglobulin test (DAT) was positive for IgG and C3d. Recipient red blood cells (RBC) were repeatedly B positive. The serum anti-B antibody titer in saline test tube at 37°C was 1:2 IgG. Antibodies eluted from the patient's RBCs showed pan-agglutination against group O antibody panel cells. Allo-antibodies were excluded by adsorption studies. The diagnosis of immune intravascular hemolysis was established. The lowest recorded hemoglobin level was 5 g/dl, and the highest levels of bilirubin and LDH were respectively 7 mg/dl (normal, 0.2 to 1.0 mg/dl) and 791 IU/ l (normal, 120 to 200 IU/l). Methylprednisolone, 2 mg/kg/day intravenously, was administered from day +8 for five consecutive days and was then gradually withdrawn over 2 months. The hemoglobin level improved rapidly, and the hemolysis panel normalized (Fig. 1). Repeated anti-B titers in saline test tube at 37°C were respectively 1:8 and 1:16 on days +11 and +14. On day +14, the DAT was negative, and the patient's blood group was O Rh positive. She received a total of six units of type O Rhpositive packed red blood cells from days +10 to +13, and no further transfusions were necessary. VNTR analysis on R. Calixto : F. Ostronoff :M. Ostronoff :A. Sucupira : R. Florencio :A. P. S. Maior :M. C. Domingues Hematology and Bone Marrow Transplantation Unit, Real-Hospital Portugues, Recife, PE, Brazil