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The impact of polymorphonuclear neutrophils on the quality of stored cellular blood products.

BACKGROUND
Storage of blood affects all blood components. Polymorphonuclear neutrophils (PMNs) are considered the main culprits of the storage lesion. Their prestorage removal improves the quality of blood components. Therefore, they are considered of no use in blood transfusion. However, their reduction may remove important antibacterial defense mechanisms.


METHODS
The phagocytic activity of PMNs in whole blood was therefore determined together with additional, sequential changes of granula-specific and cytosolic constituents which they release. Blood from 12 volunteer donors was analyzed for plasma Na+ and K+, pH, LDH, lysozyme, PMN elastase, leukocytes, neutrophils, and neutrophil phagocytosis with Phagotest.


RESULTS
Leukocytes decreased from (5.0 +/- 1.4) x 10(3) to (3.3 +/- 1.3) x 10(3) cells/microliter (mean +/- SD), most of them being PMNs. Their phagocytic capacity when rewarmed did not change significantly during the first 24 h of storage, after 3 days it came to a halt. At the same time an increasing fall in plasma sodium and pH became apparent, while plasma potassium, LDH, lysozyme, and elastase all rose by 427%, 235%, 87% respectively 1,479% at day 11. Together with these marker enzymes an armamentarium of antibiotic proteins, other proteolytic enzymes, and immunoregulatory molecules is released.


CONCLUSION
At present, it seems that the bactericidal activity in blood, due to the removal of phagocytic PMNs, does not outweight the clinical benefits of an improved component preparation where storage lesions are minimized and a number of transfusion-associated adverse reactions are avoided.