Effective resolution of daratumumab-induced false-positive antibody screening with commercial reagents.

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.