Transfusion of CMV-unselected blood components may lead to inappropriate donor selection for patients subsequently undergoing allogeneic stem cell transplant.

OBJECTIVES: To establish whether passive transfer of cytomegalovirus (CMV) IgG via transfusion results in ambiguous serostatus in patients undergoing allogeneic stem cell transplant (SCT). BACKGROUND: CMV infection causes significant morbidity following allogeneic SCT. Leucocyte-reduced blood products from CMV-seropositive donors carry minimal risk of CMV transmission, however, may result in passive transfer of CMV IgG, leading to unintentionally CMV-mismatched recipient/donors with significant consequences. METHODS: We undertook a retrospective single-centre analysis of CMV IgG results in patients transfused with CMV-unselected (CMV-U) leucocyte-reduced components subsequently undergoing SCT. RESULTS: Of patients with >1CMV IgG measured, 8/29 (27.6%) had discordant results; all were transfused between negative and subsequent positive results and were thought to have passively acquired CMV IgG. One likely CMV naïve patient was recorded as CMV seropositive and underwent transplant with a seropositive donor, developing CMV infection which required treatment. CONCLUSIONS: Passive transfer of CMV IgG is an unanticipated consequence of transfusion of CMV-U products and has the potential to cause morbidity. Inaccurate recording of serostatus pre-transplant has wider implications for data reporting on transplant outcomes. When transfusing CMV-U components pre-transfusion CMV IgG samples must be taken and transfusion history must be considered when interpreting results.