Background: Several lines of evidence suggest the role of leukocyte in platelet activation. Since pro-inflammatory mediator CD40 ligand (CD40L) has been considered as a marker of platelet activation that reflecting platelet storage lesion (PSL), we evaluated the effect of leukoreduction processes on thereby the levels of expressed CD40L in Platelet Concentrates (PCs).

Methods: In present study PRP-PCs were subdivided into two groups of usual platelets (non-filtered) and leuko-reduced platelets following pre-storage filtration. Using flow-cytometry method, the levels of platelet CD40L expression were analyzed for each group in day 1, 3 and 5 post-storage.

Results: In non-filtered products, CD40L expression on days 1, 3 and 5 after storage were 35±5.06, 62±5.84 and 82±6.1, respectively. CD40L expression showed significant increases in day 3 and 5 after storage compared to day 1 (p<0.05). In leuko-reduced platelets, CD40L expression on days 1, 3 and 5 after storage were 24±4, 41±4 and 51±6, respectively. While the same increase pattern of CD40L expression was also observed here, the significant difference was just reported between day 1 and 5 (p<0.05). Furthermore the leukoreduced platelets showed significantly less CD40L expression in day 3 and 5 compared to non-filtered platelets.

Conclusion: This study has demonstrated that pre-storage leukoreduction of PCs can reduce CD40L expression during platelet storage, the finding that suggests the effect of leukocytes in the promotion of PSL. In addition, considering the importance of CD40L in inflammatory function, it seems leuko-reduced platelet products decrease the adverse effects of platelet transfusion especially in susceptible recipients.