Background/Case Studies: Plasmapheresis has been used for decades to collect plasma for fractionation. Studies have shown that many frequent plasmapheresis donors have lower immunoglobulin levels than whole blood or platelet donors. It is not known whether this lower level can lead to an overall impairment of the humoral immune response. To better define the quality of the humoral immune response to antigenic challenges, the levels of SARS-CoV-2 antibodies after two doses of COVID-19 vaccine were analyzed in blood, platelet and plasma donors and the magnitude of the response was correlated with the number of lifetime apheresis plasma donations of the participants.
Study
Design/Methods: The level of anti-SARS-CoV-2 Spike receptor binding domain (RBD) antibodies was evaluated in the plasma (1:100 dilution) of 252 blood donors after their second dose of vaccine, using a previously described in-house ELISA (Perreault et al. Blood 2020). The participants were divided in 4 groups according to lifetime apheresis plasma donation numbers. The demographic characteristics of the participants in each group are shown in Table 1. Statistical analyses were performed to determine the relation between the magnitude of the ELISA signal (optical density; OD) and number of lifetime plasma donations, taking into account potential confounders of the association between number of lifetime donations and anti-RBD response (sex, age and interval between vaccination and donation).
Results/Findings: A mixed model adjusted on age, sex, interval between vaccination and donation was used to compare the magnitude of the anti-RBD response between groups. P values were adjusted on Tukey Kramer. The mean OD ± SD were 1.884 ± 0.622, 2.234 ± 0.547, 1.969 ± 0.695 and 1.922 ± 0.736 for groups 1, 2, 3 and 4 respectively. Interestingly, there was no statistical difference when comparing group 1 (no plasma donation) to group 4 (mean of 83.3 lifetime donation with a mean of more than 28.6 donations in the last year) (adjusted P for group 1 vs 4 = 0.4665). Conclusions: Frequent plasma donation, although known to be associated with reduced levels of circulating nonspecific immunoglobulin, is not associated with an attenuated humoral response to SARS-CoV-2 antigenic challenge.
Importance of research: Although frequent plasma donation is known to be associated with reduced levels of circulating nonspecific immunoglobulins, the impact of this on their ability to adequately respond to antigenic challenge has not been explored so far. We took advantage of the recent COVID-19 vaccination campaign to compare the magnitude of the humoral immune response to the SARS-CoV-2 Spike protein in 252 blood donors (including frequent plasma donors) to better define the immune capacity of these donors.
