Hohe Isoagglutinin-Titer in Thrombozytenkonzentraten: eine Ursache für positive Kreuzproben mit Erythrozytenkonzentraten
Marion Posset (Regensburg / DE), Morad Mohrez (Regensburg / DE), Alexander Wimmer (Regensburg / DE), Martina Brandl (Regensburg / DE), Dana Mulzer (Regensburg / DE), Andreas Michael Brosig (Regensburg / DE), Ralph Burkhardt (Regensburg / DE), Robert Offner (Regensburg / DE)
Platelet concentrates (PC) may not always be transfused compatibly to AB0 blood groups (BG) which most frequently affects 0 for A. Potentially relevant isoagglutinin titers (IT) are usually unknown as donors are not tested regularly. Despite AB0-identical supply (A for A) of red blood cell (RBC) concentrates, we observed isolated positive reactions at RBC crossmatches, where earlier PCs with BG 0 had been transfused. We analyzed ITs in donors and their possible influence on RBC crossmatch results.
100 platelet donors with BG 0 were tested on the QuidelOrtho Vision Max for ITs against A1 erythrocytes. RBCs were obtained from a healthy platelet donor, diluted to a 1% concentration with Ortho-BLISS, and used on QuidelOrtho IgG cassettes. An IgG titer concentration of 1:64 was assumed as relevant, as this is the cut-off level in IVIG (Pharm. Eur. Chap. 2.6.20). The donor serum was pre-diluted and four dilution levels were measured on the Vision Max (1:64, 1:128, 1:256, 1:512). In addition, the number of patients with BG A transfused with PCs of BG 0 from November 2023 until March 2024 was determined by a database query in the laboratory information system (LIS).
The gender distribution of the donors was equal, with a median age of 34 years (19 - 64 years). The median IT against A1 erythrocytes was 1:64, with 39 donors having a titer ≥1:64 (7 even had 1:512). Between November 2023 to March 2024, at least one PC of blood group 0 was transfused in 110 patients with BG A. Positive crossmatches occurred in a time window of up to 3 days after PC transfusion (BG 0) with at least one RBCC (BG A) in a total of 8 patients. Immunhematological testing was inconspicuous (reverse blood typing, antibody screening and identification in warm and cold). Elutions reacted positive against A1 erythrocytes. The transfused PCs were found to have an IT ≥1:256
High ITs can affect the cross-matching of red cells, and clinically relevant hemolysis have also been described. Therefore it seems reasonable to consider more than just isohemolysins when selecting compatible PCs. In addition, ITs could be reduced by using plasma-reduced PCs or PCs with titers ≥1:128 should not be transfused in a minor-incompatibly. To assess whether isoagglutinin titers remain stable or fluctuate in donors, one could measure ITs over the course of a year.
No conflicts of interest.