Difficulties in identifying antibodies in the Dombrock blood group system in multiply alloimmunized patients

BACKGROUND: Although red cell (RBC) antibodies of the Dombrock blood group system have been reported to cause acute and delayed hemolytic transfusion reactions, the difficulty in identifying these antibodies in patients with multiple RBC alloantibodies has not previously been discussed. The cases of four sickle cell disease patients who developed Dombrock system antibodies after transfusion, three of which were discovered in association with hemolytic transfusion reactions, are reported. CASE REPORTS: Patient 1 was a 36-year-old woman with multiple RBC alloantibodies. Because of the lack of an increment in hematocrit after transfusion, an investigation was performed; it revealed anti-Do(b) in the serum. Patient 2 was a 30-year, old woman with known anti-C, -E, -K, -S, -Fy(a), and -Bg(a). She had received a transfusion 10 days previously. Before further transfusion was begun, antibody identification revealed weak nonspecific reactions, which were thought to be HLA antibodies. She developed acute hemolysis during RBC exchange for acute chest syndrome; anti-Do(a) was identified in both the serum and eluate. She received 2 units of Do(a-) RBCs without complication. Patient 3 was a 35-year-old woman with known anti-C, -E, -K, -Fy(a), and -N and a warm autoantibody. Two weeks after transfusion, she had a delayed hemolytic transfusion reaction coincident with the identification of anti- Do(a). Patient 4 was a 33-year-old woman with known anti-C, -V, -K, -Fy(a), - Fy3, Jk(b), -S, -N, and -Yt(b), who developed anti-Do(a) 8 weeks after transfusion. CONCLUSION: An association of Dombrock blood group system antibodies with hemolytic reactions is demonstrated in alloimmunized sickle cell disease patients. In all four cases, identification of Dombrock system antibodies was delayed because high-titer low-avidity antibodies, HLA antibodies, or autoantibodies were thought to explain the serologic findings. The presence of Dombrock System antibodies should be considered when unexplained serologic reactivity occurs during antibody identification in this population.