Novel In-line Filter Reduces ABO Circulating Antibodies in Whole Blood

Low titer O whole blood (LTOWB) is the preferred blood product for resuscitation after hemorrhage in civilian and military trauma. The low titer requirement minimizes the risk of hemolytic transfusion reactions caused by donor ABO antibodies. However, up to 25% of otherwise eligible donors are excluded because of high antibody titers. A novel in-line filter has been developed to bind and remove donor antibodies from whole blood during infusion. We evaluated the efficacy of this filter across multiple infusion methods and assessed its effects on whole blood composition and coagulation potential.

This study was reviewed and approved as non-human research by the Institutional Review Board. Low-titer O whole blood (LTOWB) units were obtained from our regional blood bank. In the first experimental series, LTOWB units were split into unmodified native whole blood (n = 5) and spiked whole blood (n = 5) to which murine anti-human anti-A and -B antibodies were added to achieve elevated titers before simulated infusion using 3 commercially available methods (gravity, rapid manual, and automated rapid normothermic) and samples were collected after infusion both with and without the in-line filter. In a second series, unmodified native whole blood units were evaluated by cell count, flow cytometry, viscoelastic thromboelastometry, and platelet (PLT) aggregometry with and without in-line filtration. Comparisons were made using Mann-Whitney and paired t-tests.

Use of the in-line filter significantly reduced anti-A and anti-B titers across all infusion methods, with the greatest reduction seen after gravity infusion. Gravity filtration was also associated with the most pronounced changes in whole blood characteristics, including reductions in white blood cell count, PLT count, hematocrit, and hemoglobin. Viscoelastic testing revealed modest alterations in maximum clot firmness, alpha angle, and PLT contribution to clot. Multiplate aggregometry demonstrated reductions in area under the curve on both arachidonic acid and adenosine diphosphate agonist assays.

The novel in-line filter effectively reduces circulating anti-A and -B antibody titers in whole blood, though the extent of reduction varies by infusion method. Filtration induces mild changes in hematologic and coagulation parameters, but overall, filtered whole blood maintains the critical attributes for hemostatic resuscitation. Further studies are warranted to optimize filtration rates for maximal antibody clearance and to assess the impact of filtration rates for maximal antibody clearance. This approach may expand the LTOWB donor pool by enabling safe use of high-titer anti-A/anti-B donors.