Leukoreduction of blood transfusions does not diminish transfusion‐associated microchimerism in trauma patients

Abstract

TA-MC seems to be a prevalent condition among injured patients at the second of two regional trauma centers evaluated, suggesting that it is a common phenomenon after transfusion in the setting of injury. Although leukoreduction removes greater than 99.9 percent of donor WBCs, it fails to prevent or even substantially reduce the likelihood of developing TA-MC. TA-MC does not appear to be strongly associated with symptoms suggestive of cGVHD several months after transfusion.

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

“…This continued effect despite the use of leukodepleted blood products along with the prevalence of 9% is similar to previous findings from US-based studies. 10,12,19 Furthermore in this cohort, microchimerism was detected in patients transfused up to 12 years prior to this analysis. To our knowledge this is the second group of retrospective analyses to report long-term microchimerism spanning over a decade from the date of blood transfusion, with previous work in war veterans displaying microchimerism tracing back 60 years.…”

“…10,12,22 The skew toward male participants was exacerbated by the exclusion of some female participants from the analysis due to pregnancies. Removal of previously pregnant females from the study was required to prevent any confusion with the detection of naturally occurring fetal/maternal microchimerism.…”

“…The risk may also increase further where there is significant perturbation of the immune response at the time of transfusion, such as in the case of trauma patients. [10][11][12][13] In previous studies, the presence of microchimerism has been reported to persist in 10-15% of major trauma patients and may account for up to 5% of the recipient's circulating hematopoietic cells. 8,10 The current knowledge of the long-term clinical consequences and complications for individuals with microchimerism is scarce since long-term studies are difficult to perform.…”

Transfusion-transmissible infections and transfusion-related immunomodulation

“…It is postulated that, if the conditions are right for transfusion-associated microchimerism to develop, engraftment occurs with a very small number of pluripotent hematopoietic cells, regardless of the total number of donor WBCs present. It is possible that a relative paucity specifically of donor antigen-presenting cells (as might occur with leukoreduction) might limit the stimulation of the recipient's cellular immune response, in turn leading to a greater likelihood of developing microchimerism than would be expected based purely on the total number of donor WBCs transfused [56]. In approximately 10% of patients, the chimerism from a single blood donor may increase in magnitude over months to years, reaching as much as 2% to 5% of all circulating leukocytes [57].…”

Does the issue of stored blood get old: is all blood equal?

“…Furthermore, microchimerism has also been observed in a substantial fraction of leukodepleted RBC recipients. 17 An excessive amount of donor white blood cells increases…”