Leukodepleted blood components do not remove the potential for long-term transfusion-associated microchimerism in Australian major trauma patients.

Despite the introduction of leukodepleted blood components, it has been shown that donor leukocyte engraftment (microchimerism) remains a long-term consequence of red blood cell (RBC) transfusion. The incidence of microchimerism may be affected by international disparities in blood processing methods or variations in transfusion practices. This study was conducted to determine the prevalence of microchimerism in Australian trauma patients. A secondary aim was to examine whether any patient complications correlated to the incidence of microchimerism. Australian trauma patients (n = 86) who had been transfused with red blood cell (RBC) units between 2000 and 2012 with an injury severity score (ISS) of greater than 15 were recruited. The prevalence of microchimerism was determined using genetic screening with a panel of insertion/deletion biallelic polymorphisms. The mean storage age of the transfused RBC units was 20 ± 8 days and the mean length of stay (LOS) in hospital was 40 ± 39 days. There were no significant associations in this study sample to bias for patient age, gender, number of transfused RBC units or ISS. Nine of the 55 (16.3%) patients transfused with non-leukodepleted blood components displayed an incidence of microchimerism. Of the 31 patients transfused with leukodepleted RBC units, 3 (9.6%) displayed an incidence of microchimerism. Therefore, despite the universal introduction of leukodepleted blood components in Australia, the prevalence of transfusion-associated microchimerism was found to be unchanged. Furthermore, half of the patients exhibiting microchimerism were recorded to have had splenic injury or required splenectomy at the time of transfusion.