Hemolytic anemia after kidney transplantation: a prospective analysis

BACKGROUND: Hemolysis may occur in 9% to 40% of patients after solid organ transplantation and be caused by the passenger lymphocyte syndrome (PLS). STUDY DESIGN AND METHODS: We have prospectively examined 217 kidney transplant recipients before (Day ?1) and after (up to Days +10, +20, and +30) surgery. ABO‐identical transplant was performed in 180 (82.9%) patients, while 37 (17.1%) individuals received ABO‐compatible nonidentical grafts. Direct antiglobulin tests (DATs) were performed by tube technique (polyspecific anti‐human globulin [IgG + C3d]), positive DAT samples were further tested by gel agglutination (monospecific anti‐IgG, ‐IgM, ‐IgA, or ‐C3), and eluates were prepared from DAT‐positive red blood cells (RBCs) by the dichloromethane elution test. RESULTS: We observed that 34 of 217 (15.7%) patients developed a positive DAT up to Day +30. The percentage of patients with positive DATs was significantly higher in those having ABO‐compatible nonidentical transplants compared to those that received ABO‐identical grafts (10/37 = 27.0% vs. 24/180 = 13.3%; p = 0.037). Specific RBC antibodies (anti‐A or anti‐B) were found in only 5 of 37 (13.5%) patients having ABO‐compatible nonidentical transplants who presented with clinical hemolysis. We found only three reactive eluates from 24 patients with positive DATs who received ABO‐identical transplants but had no hemolysis. CONCLUSIONS: Our data collected prospectively demonstrated that: 1) positive DATs occurred in 15.7% of all patients up to Day +30 after a kidney transplant; 2) the DAT positivity occurred up to Day +10 in 9.7% of all transplanted patients; 3) the majority of the transplant recipients with a positive DAT had a nonreactive RBC eluate; and 4) PLS was the cause of a positive DAT in 13.5% of patients submitted to ABO‐compatible nonidentical kidney transplants.