Failure to kill Yersinia enterocolitica by plasma diluted to the concentration found in red cell units.

The possibility that the use of additive solutions for red cell storage might impair the ability of plasma to kill Yersinia enterocolitica was investigated by studying killing of Y enterocolitica by neat and diluted plasma. The ability of neat citrated plasma to kill complement sensitive organisms was lost at around 26%, the dilution typically found in red cell units. These results should be considered in the light of evidence that killing in plasma is important in the protection of donated blood against growth of Y enterocolitica, and the observation that the increase in frequency of transfusion reactions caused by Y enterocolitica coincided with the widespread introduction of additive solutions. Taken together, these points support the suggestion that the introduction of additive solutions may have precipitated the problem of growth of Y enterocolitica in stored blood.