Soluble CD40L release as test for functional platelet loss.

Area of Science:

• Transfusion Medicine
• Hematology
• Biochemistry

Background:

• Platelet storage can lead to a 'platelet storage lesion', reducing platelet viability and function.
• Soluble CD40 ligand (sCD40L) release by platelets reflects their metabolic activity and function.
• Thromboxane B2 (TXB2) is another marker associated with platelet activation and function.

Purpose of the Study:

• To evaluate soluble CD40 ligand (sCD40L) release as a marker for functional platelet loss during storage.
• To compare sCD40L release with thromboxane B2 (TXB2) formation as indicators of platelet storage lesion.

Main Methods:

• Single donor apheresis platelet products (n=8) were stored under routine conditions.
• sCD40L and TXB2 levels were measured on days 1, 3, and 5 after platelet stimulation.
• Measurements included ELISA for sCD40L and RIA for TXB2, results normalized to therapeutic units (TU).

Main Results:

• Baseline sCD40L release was 42.5 ± 7.1 ng/TU and TXB2 formation was 2,183 ± 576 ng/TU.
• On day 5, sCD40L release decreased to 57% and TXB2 formation to 65% of control values.
• Both markers demonstrated a comparable decline in release/formation over the 5-day storage period.

Conclusions:

• sCD40L release and TXB2 formation exhibit similar patterns during platelet storage, reflecting functional loss.
• A functional platelet loss of approximately 30-40% occurs after 5 days of storage.
• sCD40L release, easily induced by recalcification and clot formation, serves as a reliable marker for functional platelet loss.