Stability guidelines for dithiothreitol-treated red blood cell reagents used for antibody detection methods in patients treated with daratumumab.

Daratumumab (DARA), a drug used to treat patients with multiple myeloma, causes interference in pre-transfusion testing. Samples from patients receiving DARA exhibit panreactivity in antibody detection and identification tests with red blood cells (RBCs). Many hospitals are sending these samples to reference laboratories. Dithiothreitol (DTT), a sulfhydryl chemical treatment of RBCs, negates this reactivity. This study investigated the stability of the antigens on DTT-treated RBCs to determine if large quantities of RBCs could be treated at one time, stored, and used for testing at a later time. Panel cells were treated with DTT and then stored as three sets. Set 1 DTT-treated RBCs were stored in Alsever's solution at 2°C to 8°C, washed daily, and suspended in pH 7.3 phosphate-buffered saline (PBS) prior to antigen typing. Set 2 DTT-treated RBCs were stored in pH 7.3 PBS. Set 3 DTT-treated RBCs were stored in Alsever's solution. Sets 2 and 3 were inspected daily for 14 days for observation of hemolysis. In Set 1, all antigen reactivity remained at ≥2+ with both single- and double-dose cells for 14 days. The Rh antigens gave stronger reactions longer, compared with those tested in the Duffy, Kidd, and MNS blood group systems. Sets 2 and 3 were monitored for hemolysis. On day 3, Set 2 began displaying hemolysis, with complete hemolysis by day 8. Set 3 did not display hemolysis in 14 days. In conclusion, a large volume of RBCs can be treated with DTT and stored in Alsever's solution for use without deterioration of the RBC antigens, saving institutions tech time, resources, and money.