Effect of white cells on platelets during storage.

Area of Science:

• Hematology
• Transfusion Medicine
• Cellular Biology

Background:

• White blood cells (WBCs) in stored platelet concentrates negatively affect platelet function and posttransfusion recovery.
• Previous hypotheses attributed these effects to pH decline from WBC metabolism.
• Platelets stored in gas-permeable bags show abnormalities despite stable pH (>6.0).

Purpose of the Study:

• To investigate the specific impact of neutrophils on platelet protein and function during storage.
• To quantify the changes in platelet responsiveness in the presence of controlled neutrophil counts.

Main Methods:

• Platelet apheresis specimens were processed to achieve low WBC counts (<2 x 10^5/mL).
• Specimens were divided; neutrophils were added to one aliquot (1 x 10^6/mL), while the other served as a control.
• Platelet responsiveness to ristocetin was measured on Days 3 and 5 of storage at 22°C.

Main Results:

• Platelet responsiveness to ristocetin significantly decreased in the presence of neutrophils on Day 3 (slope 1.25 vs. 10.3) and Day 5 (slope 0.3 vs. 4.5).
• No significant differences in platelet aggregation with ADP or collagen were observed between groups.
• The findings indicate a specific detrimental effect of neutrophils on ristocetin-induced platelet function.

Conclusions:

• Neutrophils significantly impair platelet function during storage, independent of pH changes.
• The reduction in ristocetin responsiveness highlights a specific mechanism by which WBCs compromise platelet efficacy.
• Minimizing neutrophil contamination in platelet concentrates is crucial for maintaining posttransfusion recovery.