CD4+ T‐cell lymphopenia in frequent platelet donors who have ceased platelet donation for at least 1 year

Abstract

BACKGROUND We recently discovered that 30% of current frequent apheresis platelet donors in a study at our donor center had CD4+ counts below 200 cells/μL. How long CD4+ lymphopenia persists after ceasing plateletpheresis is unknown. Whether there are infectious or other complications in former frequent donors that could relate to CD4+ lymphopenia is also unknown. STUDY DESIGN AND METHODS We mailed a letter to former frequent apheresis platelet donors who had not donated platelets for at least 12 months. Frequent donation was defined as 20 to 24 plateletpheresis sessions in at least one 365‐day period starting in 2011. Donors who expressed interest in the study were contacted to schedule a study visit. Participants in the study provided a blood sample and completed a health questionnaire that included questions about opportunistic infections and malignancies. RESULTS Of 50 potential study candidates who were mailed a letter, 15 participated in the study. There were 2 participants with CD4+ counts below 200 cells/μL, one of whom had prior counts that documented a small improvement with cessation of plateletpheresis. Three participants had counts between 200 and 300 cells/μL. No study participant had a history of an opportunistic infection or a malignancy associated with immune dysregulation. CONCLUSION We detected CD4+ lymphopenia in former frequent apheresis platelet donors who had ceased platelet donation for more than 1 year. There was no evidence that the CD4+ lymphopenia predisposes to opportunistic infections or to malignancies associated with immune dysregulation.

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

“…This translated to significantly lower CD4 + T cells ( p < 0.001) and CD8 + T cells ( p < 0.0001) (Figure 1C ), consistent with previous reports. 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 ).…”

“… 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.…”

“…Recent literature highlighted a striking correlation between the frequency of platelet donations by apheresis and lymphopenia. 2 , 3 In particular, several apheresis donors with lifetime donations of more than fifty exhibited severe T cell lymphopenia. 2 , 3 One observational study reported that the decline in CD4 + T cells and/or CD8 + T cells had a modest contribution to immunosuppression‐related or opportunistic infections.…”

“… 2 , 3 In particular, several apheresis donors with lifetime donations of more than fifty exhibited severe T cell lymphopenia. 2 , 3 One observational study reported that the decline in CD4 + T cells and/or CD8 + T cells had a modest contribution to immunosuppression‐related or opportunistic infections. 4 In contrast, while Gansner et al 3 showed that lymphopenia was associated with a reduction in the CD4 + T helper 17 subsets (Th17), key mediators of mucosal immunity against pulmonary pathogens, 5 their results and evidence from analysis of samples from individuals a year after ceasing platelet donations, suggest functional immune responses are maintained in these individuals.…”

“… 4 In contrast, while Gansner et al 3 showed that lymphopenia was associated with a reduction in the CD4 + T helper 17 subsets (Th17), key mediators of mucosal immunity against pulmonary pathogens, 5 their results and evidence from analysis of samples from individuals a year after ceasing platelet donations, suggest functional immune responses are maintained in these individuals. 2 , 3 …”