#OA2-AM25-ST-21 - Transfusion Safety Assessment of RBC Units Containing Unexpected Donor Alloantibody

Unexpected antibodies in volunteer blood donors are uncommon. The resulting red blood cell (RBC) units from these donors are not readily accepted by hospital transfusion services (HTS) due to fear of recipient transfusion reaction and increase in laboratory workload related to additional antibody identification (AbID) testing. Given the strain of the blood supply, changing the mindset of HTS to routinely use antibody positive RBCs is needed. The aim of this study was to evaluate the transfusion safety of RBCs containing unexpected donor alloantibody (CUDA).

Study

Design/Methods:

Recipients (n=26) of RBCs CUDA (n=34), at a single academic medical center, were assessed for clinical and serologic signs of adverse reaction to transfusion.

For 15 RBC units, 1:2 to 1:64 doubling dilution in saline was prepared from antibody positive donor EDTA samples and donor RBC segments. Dilutions were tested utilizing gel IgG cards (QuidelOrtho, San Diego, CA) against double-dose corresponding-antigen positive red cells.

Clinical assessment consisted of retrospective chart review (Epic, Verona, WI) for signs/symptoms of adverse reaction up to 72 hours post-transfusion, in particular, hemolytic reactions.

Serologic investigation consisted of collecting pre and post-transfusion information via the laboratory information system (WellSky, Overland Park, KS) including pretransfusion antibody screen, if positive—AbID, subsequent antibody screen, if positive—AbID, DAT, if positive—eluate results, laboratory transfusion reaction workup ≤ 30 days post-transfusion and final interpretation.

Results/Findings:

Fifteen of 15 RBCs CUDA (15/15) demonstrated reduction in titer of donor EDTA sample (range 4-64) vs segment (range 0-32) by 1-3 dilutions.

Of the 26 recipients of 34 RBCs CUDA, there were no clinical signs/symptoms of an adverse reaction (0/26). One transfusion reaction workup was performed due to shortness of breath, however, final interpretation was that symptoms were not related to transfusion.

Twenty of 26 recipients had subsequent screens performed, 4 of which were positive (4/20), however, each was positive pretransfusion (4/4), 3 with a history of an alloantibody. Of the 26 recipients, in only 1 did the DAT became positive post-transfusion. The eluate was positive with all cells tested, consistent with warm autoantibody. Table 1.

Conclusions:

Both clinical and serologic data support the safe use of RBC units CUDA for transfusion with no transfusion reactions or increased laboratory workload despite RBC unit titers of up to 32. Group O RBCs are always in high demand and short supply, this study alone made use of 22 group O RBC units that would have otherwise been discarded. In continued good stewardship of the blood supply, HTS should accept these units for transfusion.