Daratumumab (DARA), an immunoglobulin that targets CD38 on myeloma cells, was recently approved by the U.S. FDA. DARA, however, also binds to CD38 on red blood cells (RBCs), which interferes with blood compatibility testing if the patient also needs a blood product. While DARA does not affect ABO/RhD typing, positive agglutination reactions occur in indirect antiglobulin tests, antibody detection panels, and antihuman globulin crossmatches in all types of media. A new method using dithiothreitol (DTT) has been described to inhibit DARA interference by denaturing cell surface CD38 on RBCs. In order to validate this new method, 25 blood bank laboratories in North and South America, Europe and Asia Pacific were given paired plasma samples: one sample contained DARA and the second sample contained DARA plus a clinically relevant antibody (anti-D, anti-Fya or anti-s). By using DTT, all 25 laboratories were able to distinguish DARA interference and detect the unknown antibody with all testing methods (gel, tube or solid phase). By using DTT, blood service labs may provide safe blood products to patients taking DARA.
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For how long time (hour/Days) can you store and use the DTT-treated RBC for screening or identification?
We antigen typed DTT treated panel cells every other day for 2 weeks and the antigen strength was not affected. During the testing we washed the cells before antigen typing. When we let the treated cells sit for more than 4-5 days without washing them they hemolyzed. So our experience is that if you wash them every other day you can use them up to 2 weeks. We tested for all clinically significant antigens.