Blood Transfusion Research Today is a free monthly online journal that collates and summarizes the latest research about Blood Transfusion, including details on blood donation, blood types, leukemia.

High-level long-term white blood cell microchimerism after transfusion of leukoreduced blood components to patients resuscitated after severe traumatic injury.

Lee TH, Paglieroni T, Utter GH, Chafets D, Gosselin RC, Reed W, Owings JT, Holland PV, Busch MP

Blood Systems Research Institute, Department of Pathology, University of California, Davis, California 94118, USA. tlee@bloodsystems.org

BACKGROUND: Long-term white blood cell (WBC) microchimerism (MC), of at least 2 years, has been reported in trauma patients receiving fresh nonleukoreduced (non-LR) blood. It is unknown, however, whether this occurs with LR blood products that are nearly devoid of WBCs. Twenty-seven patients transfused with LR and non-LR blood products were studied after severe traumatic injury. A secondary aim was to explore donor-recipient mixed lymphocyte reactivity in vitro. STUDY DESIGN AND METHODS: To quantify MC, allele-specific real-time polymerase chain reaction assays were developed targeting HLA Class II sequence polymorphisms. Extensive validation showed that these assays reliably detect a single copy of target sequence in a complex allogeneic background without false positivity. RESULTS: At a median follow-up of 26 months (range, 24-39 months), long-term MC was observed in 3 of 20 patients (15%) who received non-LR blood products and 2 of 7 (29%) who received LR blood products. The maximum MC ranged from 0.40 to 4.90 percent of circulating WBCs and appeared, by Class II genotype analysis, to be attributable to a single donor. CONCLUSION: It is concluded that robust levels of long-term MC, apparently traceable to a single donor, occur at similar frequency despite leukoreduction of transfused blood products. Exploratory analysis of donor-recipient mixed lymphocyte reactivity suggests that long-term MC may require a state of bidirectional tolerance before transfusion.

Published 4 August 2005 in Transfusion, 45(8): 1280-90.
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