Monitoring of lymphocyte subsets in regular blood donors

To assess the effects of long-term regular leukocyte-reduced platelet (PLT) apheresis on lymphocyte subsets in volunteer donors.

We enrolled 178 participants, including Amicus-using donors (Group A, n = 55), Trima-using donors (Group T, n = 64), and first-time donor controls (n = 59). Apheresis donors completed ≥8 PLT collections within 1 year on one fixed separator. Lymphocyte-subset measurements were performed on pre-donation screening samples.

After age/sex adjustment, both apheresis groups exhibited significantly lower absolute counts and percentages of natural killer (NK) cells versus controls (p < 0.05), while CD3⁺, CD4⁺, CD8⁺ T cells, and B lymphocytes were similar among groups. Several T-cell markers showed nominal downward trends with higher lifetime donations (raw p < 0.05), yet no associations persisted after correcting for false discovery rate (FDR). Neither lifetime nor 1-year donation counts correlated with lymphocyte or routine hematological parameters; overall lymphocyte-subset profiles did not differ between Group A and Group T. Subgroup analysis revealed reduced NK cell counts only in the high-donation stratum (≥100 donations) of Group A and the low-donation stratum (<40 donations) of Group T.

Long-term leukocyte-reduced PLT apheresis is associated with decreased circulating NK cells. Multiple-testing correction provided no evidence for progressive lymphocyte decline with cumulative donations. One-year donation frequency had no impact on lymphocyte subsets. With plasma rinseback activated for all Trima procedures, lymphocyte profiles were comparable between devices. Routine hematological parameters remained stable in long-term apheresis donors.