2018 Volume 67 Issue 2 Pages 233-237
Daratumumab (DARA) is a human monoclonal IgG antibody preparation against CD38, which was developed to treat multiple myelomas (MMs). CD38 is expressed not only on myeloma cells but also on red blood cells; hence, it may cause a false positive result of the indirect antiglobulin test (IAT) in patients administered with DARA. In this study, we encountered cases with positive IAT results, which were assumed to be caused by DARA, and investigated the duration of DARA’s interference with IAT as well as a method of avoiding DARA’s interference by the dithiothreitol (DTT) processing of red blood cells (RBCs). Our subjects included 4 MM patients using DARA. In the DTT processing of RBCs, 100 μL of 3–5% RBC suspension was washed 4 times with PBS. Then, 400 μL of 0.2 mol/L DTT was added to the suspension, and the suspension was warmed at 37°C for 30 min and then washed 4 times with PBS. For the duration of DARA’s interference with IAT, a positive IAT result was observed on day 3 after starting DARA administration. One patient that we investigated became negative on day 137 after the completion of DARA administration. The positive IAT reaction induced by DARA became negative with the DTT processing of RBCs. The processing did not deactivate blood group antigens other than K, and examination for irregular antibody expression was possible, suggesting that it could be useful as a pre-blood transfusion process for patients using DARA.
