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Effective resolution of daratumumab-induced false-positive antibody screening with commercial reagents
Han Joo Kim1, Suk Won Seo1, Yousun Chung2
1Department of Laboratory Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.
Background And Objectives:
Daratumumab (DARA), an anti-CD38 monoclonal antibody used in the treatment of multiple myeloma, frequently causes false-positive panreactivity in antibody screening tests. The conventional approach to resolve this interference involves treating reagent red blood cells (RBCs) with 0.2 M dithiothreitol (DTT). However, this method is labour-intensive, may fail to detect clinically significant antibodies and can yield inconsistent results. We aimed to assess the effectiveness of a commercial reagent containing anti-CD38 Fab fragments as an alternative for mitigating DARA-related interference.
Materials And Methods:
We retrospectively analysed 22 blood samples from 17 patients. Antibody screening was performed using both DTT-treated and DaraEx-treated reagent RBCs. Clinical and laboratory data were reviewed. Additionally, patient samples were spiked with antibodies to evaluate antibody detection.
Results:
All samples showed false-positive panreactivity after DARA treatment. Nineteen samples were negative using both DTT- and DaraEx-treated cells. Three samples remained reactive with DTT-treated cells but turned negative with DaraEx. These cases were associated with lower serum albumin, impaired renal function and elevated monoclonal protein levels. DaraEx-treated cells retained reactivity with anti-E and anti-D antibodies.
Conclusion:
DaraEx consistently and completely removed DARA-related interference, including in cases where DTT was ineffective. It represents a safe and efficient alternative to DTT for pre-transfusion antibody screening.
