Abstract Introduction:

Pre-transfusion tests, essential for the release of blood components, may be affected by drugs. Monoclonal antibodies represent a class of medications increasingly used in the clinical practice, with anti-CD38 monoclonal antibodies (daratumumab) being a promising resource in the treatment of refractory myeloma. This monoclonal antibody recognizes CD38 in myeloma cells and interferes with pre-transfusion tests by causing panreactivity in indirect antiglobulin tests thereby clinically masking alloantibodies. Dithiothreitol is a reagent that breaks disulfide bonds and effectively destroys antigenic sites for CD38 on red blood cells. This study reports the immunohematological findings of pre-transfusion tests of patients with multiple myeloma receiving daratumumab and on solutions to prevent the interference of this monoclonal antibody.

Methods:

Serum samples from five patients on anti-CD38 monoclonal antibody treatment were evaluated. Tests performed included ABO/RhD typing, indirect antiglobulin test, direct antiglobulin test and eluate test. A daily evaluation was performed to determine the shelf life of dithiothreitol-treated red blood cells when stored in Alsever's solution.

Results:

No interference in the ABO/RhD typing results was noted but in all samples, a panreactivity was observed in indirect antiglobulin tests. Regarding the direct antiglobulin test, two samples presented positive results but negative eluates. In all samples, treatment of reagent red blood cells with 0.2 M dithiothreitol offset interference by anti-CD38 monoclonal antibodies. Dithiothreitol-treated red blood cells stored in Alsever's solution were stable for up to 15 days.

Conclusion:

Treatment of reagent red blood cells with dithiothreitol can be efficient and accessible to offset the interference of the anti-CD38 drug in pre-transfusion tests. The number of costly serological workups can be reduced by having stored dithiothreitol red blood cells with this proving to be a useful reagent for investigating anti-CD38.