Importance of white blood cells in platelet storage

Platelet concentrates from 290 healthy donors collected in CPD anticoagulant and PL-146 polyvinylchloride containers were stored for 72 h at 22 +/- 0.5 degrees C under standard conditions to investigate variables affecting the quality of stored platelets. In addition to the expected inverse relationship between pH and platelet count (p less than 0.001), a significant inverse correlation between pH and white blood cell count (WBC) was also noted (p less than 0.01). Platelets from female donors developed a lower pH than those from male donors; this difference could not be accounted for by any of the variables analyzed other than sex. To investigate the relationship between WBC and pH further, 15 units of platelet-rich plasma (PRP) were depleted of WBCs by slow centrifugation prior to being stored for 3 days. This resulted in a mean loss of 10% of the platelets and 75% of the WBCs. The average post-storage pH of the 15 WBC-poor concentrates (7.06 +/- 0.02) was significantly higher than that of routinely prepared concentrates containing the same number of platelets (6.54 +/- 0.43) (p less than 0.001). Production of lactic acid and consumption of glucose was markedly diminished in leukocyte-poor concentrates. These data suggest that WBCs significantly affect the metabolic activity of platelet concentrates and that the quality of stored platelets can be improved by reducing the number of contaminating leukocytes. Measurement of leukocytes may be important in quality control of platelet concentrates.