Daudi cell stroma: An alternative to dithiothreitol to resolve daratumumab interference in pretransfusion testing

Treatment of red blood cells with dithiothreitol (DTT) or trypsin effectively denatures CD38; however, this treatment damages other antigens, some of which are of clinical importance. Thus, other avenues to deplete daratumumab (DARA) from plasma samples should be explored.

The Daudi B-cell line was found to express high levels of CD38 and was sonicated in a sonication buffer to achieve complete cell lysis. The resulting stroma preparation was centrifuged at 20 000g for 20 minutes and then mixed with 250 μL of DARA-plasma and incubated for 10 minutes at 37°C. The stroma-DARA-plasma mixture was centrifuged again, and the supernatant was collected and subjected to four additional rounds of adsorption with fresh stroma. DARA-depleted plasma was tested by gel indirect antiglobulin test (IAT).

CD38 expression on Daudi cells was confirmed by flow cytometry. Gel IAT analysis showed that the incubation of plasma from DARA-treated patients with Daudi cells stroma resulted in a significant depletion of DARA but allowing detection of other alloantibodies of interest such as anti-K, anti-Yt^a , and anti-Gy^a .

Daudi cell stroma is inexpensive, easy to prepare in large batches, and can be used as an off-the-shelf reagent. Incubation of plasma from DARA-treated patients with Daudi cell stroma can efficiently overcome DARA interference in serologic testing without affecting DTT- or trypsin-sensitive antigens.