Total platelet donation count and donation frequency are determinants of plateletpheresis‐associated lymphopenia

Abstract

Background Plateletpheresis using a leukocyte reduction system (LRS) traps donor WBCs in the LRS chamber, which may lead to lymphopenia, especially in frequent plateletpheresis donors. It seems plausible that this might cause adverse effects. However, current knowledge about potential confounders and donor health impacts is incomplete. Donors and methods Recent platelet donors and donations collected at University Hospital Regensburg from 2016 to 2019 using the Terumo BCT Trima Accel LRS system were retrospectively analyzed and compared with historical platelet donors and donations collected mainly with Fresenius Kabi Amicus non‐LRS system from 2010 to 2013. Additionally, recent donors were prospectively surveyed using a health‐related topics questionnaire. Results Analysis of 819 recent donors with 11,254 blood counts and 1464 questionnaires and 1011 historical donors with 12,848 blood counts revealed that increased annual platelet donation frequencies were associated with decreased lymphocyte counts in both groups. Median lymphocyte counts in recent donors with no versus ≥24 previous annual donations declined from 2.0 to 1.2 × 103/μL (p < 2.2 × 10−16), and those in historical donors with no versus ≥24 previous annual donations decreased from 2.0 to 1.5 × 103/μL (p = 6 × 10−4), respectively. The questionnaire results showed that donation frequency and lymphopenia were not associated with upper respiratory tract infection (URTI) incidence or duration, but platelet donors who concomitantly donated granulocytes had significantly shorter URTI durations than those who did not (p = .008). Conclusion This study confirmed that plateletpheresis‐associated lymphopenia occurs in LRS and to a lesser degree in non‐LRS platelet donors, but revealed no evidence of a negative impact on donor health.

COVID‐19 vaccine humoral response in frequent platelet donors with plateletpheresis‐associated lymphopenia

“…Activated follicular CD4 + T cells provide critical signals for B cell activation, proliferation, and differentiation leading to the formation of germinal centers in secondary lymphoid organs where maturation of the adaptive immune response occurs 55 . Therefore, the reduction in peripheral blood CD4 + T cells is most likely not predictive of immune dysfunction in affected individuals as supported by the data presented herein as well as previous reports 2,3,33 …”

“…55 Therefore, the reduction in peripheral blood CD4 + T cells is most likely not predictive of immune dysfunction in affected individuals as supported by the data presented herein as well as previous reports. 2,3,33 Nevertheless, individuals with plateletpheresisassociated lymphopenia who may be unaware of their status might still be referred for hematology consultations and sometimes invasive examinations after routine blood tests due to their low lymphocyte counts, when their condition can be explained by the frequency of voluntary platelet donations. Importantly, lymphocyte analysis of 15 former apheresis donors showed that a small proportion was lymphopenic at least a year after ceasing platelet donation.…”

“… 45 , 46 Platelet collection is a major activity of blood organizations; an adequate supply of platelet concentrates to fulfill the needs of thrombocytopenic patients requires continuous efforts in donor recruitment and retention. Recent literature on lymphopenia associated with frequent platelet donations 2 , 3 , 4 , 33 raised important questions related to donor health and more specifically their ability to mount adequate immune responses. The COVID‐19 vaccination campaign provided a convenient proxy for assessing immune function in our cohort of frequent plateletpheresis donors.…”

“… 55 Therefore, the reduction in peripheral blood CD4 + T cells is most likely not predictive of immune dysfunction in affected individuals as supported by the data presented herein as well as previous reports. 2 , 3 , 33 …”

“…2,3 Strikingly, individuals within the CD4-low group had a seven-fold higher frequency of donations (p < 0.0001) (Table 1), supporting current literature that frequent plateletpheresis donations are indeed associated with declining T cell numbers. [2][3][4]33 Of note, the CD4:CD8 ratio, which is often utilized in the context of HIV-related immunosuppression as a surrogate to assess the overall strength of immune function, 34 did not significantly differ between the two groups (Figure 1D).…”