DIFFICULTIES IN IDENTIFYING ANTIBODIES IN THE DOMBROCK BLOOD-GROUP SYSTEM IN MULTIPLY ALLOIMMUNIZED PATIENTS

BACKGROUND: Although red cell (RBC) antibodies of the Dombrock blood g roup system have been reported to cause acute and delayed hemolytic tr ansfusion reactions, the difficulty in identifying these antibodies in patients with multiple RBC alloantibodies has not previously been dis cussed. The Gases of four sickle cell disease patients who developed D ombrock system antibodies after transfusion, three of which were disco vered in association with hemolytic transfusion reactions, are reporte d. CASE REPORTS: Patient I was a 36-year-old woman with multiple RBC a lloantibodies. Because of the lack of an increment in hematocrit after transfusion, an investigation was performed; it revealed anti-Do(b) i n 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 pre viously. Before further transfusion was begun, antibody identification revealed weak nonspecific reactions, which were thought to be HLA ant ibodies. She developed acute hemolysis during RBC exchange for acute c hest syndrome; anti-Do(a) was identified in both the serum and eluate. She received 2 units of Do(a-) RBCs without complication. Patient 3 w as 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 hem olytic 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 wee ks after transfusion: CONCLUSION: An association of Dombrock blood gro up system antibodies with hemolytic reactions is demonstrated in alloi mmunized sickle cell disease patients. In all four cases, identificati on of Dombrock system antibodies was delayed because high-titer low-av idity antibodies, HLA antibodies, or autoantibodies were thought to ex plain the serologic findings. The presence of Dombrock system antibodi es should be considered when unexplained serologic reactivity occurs d uring antibody identification in this population.