Interference with blood compatibility testing with DARA. (A) DARA binds to CD38 expressed on RBCs, leading to agglutination on indirect Coombs testing even in the absence of allo- or autoantibodies against RBC antigens. (B) In the presence of DARA and RBC antibodies, agglutination occurs. (C) Incubating reagent RBCs with DTT before adding patient serum will denature CD38 on RBC cells and prevent agglutination. Alternatively, the patient’s serum can be incubated with an anti-ID that neutralizes DARA and prevents its interaction with CD38. Either technique allows for the discrimination of clinically relevant RBC antibodies during pretransfusion antibody screening (D). Abs, antibodies; anti-ID, anti-idiotype Ab. Adapted from van de Donk et al32 with permission.
