American Red Cross- Baltimore, MD Baltimore, Maryland, United States
Background/Case Studies: With recent advancements in anti-CD47 therapy, there is a growing need to address the challenges of anti-CD47 interference in pretransfusion testing. In-house prepared pooled platelet adsorption was investigated as an alternative method for mitigating anti-CD47 interference without removing clinically significant antibodies compared to standard papain-treated allogeneic red cell adsorption.
Study
Design/Methods: Plasma samples containing anti-CD47, warm autoantibodies (WAA), anti-CD38, and multiple alloantibodies were selected, de-identified, and stored frozen until testing. Three samples containing anti-CD47, two containing anti-CD38, two containing WAA, and two containing multiple alloantibodies were tested. Antibody testing was performed at the Indirect Antiglobulin Test (IAT) phase using Low Ionic Strength Solution (LISS) and Polyethylene Glycol (PeG) potentiators. Pooled platelet concentrate was prepared in-house from expired apheresis platelet units following a previously published procedure. Phenotypically similar allogeneic donor red cells were papain-treated according to the manufacturer’s direction. Two-to-one platelet to plasma ratio and one-to-one papain-treated allogeneic red cells to plasma ratio were used for adsorptions at 37°C for 30 minutes. The adsorbed plasma was tested after each adsorption to check for completion by LISS/PeG IAT.
Results/Findings: In-house prepared pooled platelet concentrate effectively removed anti-CD47 after two to three adsorptions, while papain-treated allogeneic red cells failed to remove reactivity after six adsorptions. WAA was removed after four to five platelet adsorptions and after two to three allogeneic red cell adsorptions. Anti-CD38 remained in the adsorbed plasma after three adsorptions with both pooled platelets and allogeneic red cells. Clinically significant alloantibodies also remained in the adsorbed plasma after three adsorptions with both methods. Conclusions: Adsorption with in-house prepared pooled platelet concentrate demonstrated superior efficacy in removing anti-CD47 compared to standard papain-treated allogeneic red cell adsorption. Interestingly, WAA was removed by pooled platelet concentrate at a slower rate, where red cell adsorption proved more effective. Neither method eliminated anti-CD38 nor removed clinically significant alloantibodies. These findings highlight the effectiveness of pooled platelet adsorption in removing anti-CD47 without removing clinically significant alloantibodies. Further studies are warranted to investigate its utility with samples containing both anti-CD47 and underlying clinically significant alloantibodies.
