Non-D Rh antibodies appearing after apheresis platelet transfusion: stimulation by red cells or microparticles?

• Published in: Vox sanguinis Vol. 100; no. 4; pp. 395 - 400
• Main Authors: Kitazawa, J., Nollet, K., Morioka, H., Tanaka, K., Inomata, M., Kubuki, Y., Ohto, H.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.05.2011; S. Karger AG
• Subjects: Aged; Blood Component Removal; Blood Group Incompatibility - blood; Blood Group Incompatibility - etiology; Blood Group Incompatibility - immunology; Blood platelets; Blood transfusions; Cell-Derived Microparticles - immunology; Erythrocyte Membrane - immunology; Erythrocytes; Female; Genotype & phenotype; Humans; Immunoglobulins; irregular antibody; Isoantibodies - blood; Isoantibodies - immunology; Male; Middle Aged; Platelet Transfusion; RBC-derived microparticles; red cell contamination in apheresis platelets; Rh-Hr Blood-Group System
• ISSN: 0042-9007; 1423-0410
• DOI: 10.1111/j.1423-0410.2010.01435.x

Background  Apheresis platelets (APs) have gained favour over whole blood‐derived platelets on the presumption that they are less likely to provoke alloimmunization to red‐blood‐cell antigens. Case Reports  Non‐D Rh antibodies appeared in three patients after apheresis platelet transfusion. Anti‐C and anti‐E arose in two female patients with previous antigen exposure. Both anti‐c and anti‐E arose in a male recipient with no prior transfusion history. Materials and Methods  Fifty APs were analysed for residual RBCs and RBC‐derived microparticles, using samples obtained from a local blood centre. Cells and microparticles were quantified with a flow cytometry gating scheme, using PE‐labelled anti‐CD235a (glycophorin A) and FITC‐labelled anti‐CD41a (platelet gp IIb/IIIa) to distinguish lineage. Results  Apheresis platelets were found to contain a mean of 7·5 × 106 (95% C.I. [6·3–8·5 × 106]) RBCs on one manufacturer’s device and 5·2 × 106 (95% C.I. [4·0–6·3 × 106]) RBCs on another’s. RBC‐derived microparticles averaged 210·7 × 106 (95% C.I. [166·2–254·2 × 106]) on one manufacturer’s device and 232·3 × 106 (95% C.I. [194·3–272·9 × 106]) on another’s. These counts all correspond to volumes of < 1 μl. Conclusion  Despite RBC contamination of APs below commonly accepted thresholds for Rh immunogenicity, AP transfusion can provoke non‐D Rh antibody formation. RBC‐derived microparticles, smaller but more numerous than RBCs, are volumetrically comparable and may be a hitherto underappreciated antibody stimulus. Further microparticle research will guide considerations of extended phenotypic matching of platelet components.