The RBC storage lesion is a multiparametric response that occurs during storage at 4°C, but its impact on transfused patients remains unclear. In studies of the RBC storage lesion, the temperature transition from cold storage to normal body temperature that occurs during transfusion has received limited attention. We hypothesized that multiple deleterious events might occur in this period of increasing temperature. We show dramatic alterations in several properties of therapeutic blood units stored at 4°C after warming them to normal body temperature (37°C), as well as febrile temperature (40°C). In particular, the intracellular content and redox state of NADP(H) were directly affected by post-storage incubation at 37°C, as well as by pro-oxidant storage conditions. Modulation of the NADPH-producing pentose phosphate pathway, but not the prevention of hemoglobin autoxidation by conversion of oxyhemoglobin to carboxyhemoglobin, provided protection against storage-induced alterations in RBCs, demonstrating the central role of NADPH in mitigating increased susceptibility of stored RBCs to oxidative stress. We propose that assessing RBC oxidative status after restoration of body temperature constitutes a sensitive method for detecting storage-related alterations that has the potential to improve the quality of stored RBCs for transfusion.

Objectives. To determine the ferritin inter-assay differences between three “Conformité Européenne” (CE) marked tests, the impact on reference intervals (RI), and the proportion of individuals with iron deficiency (ID), we used plasma and serum from healthy blood donors (HBD) recruited in three different Switzerland regions. Design and Methods. Heparinized plasma and serum from HBD were obtained from three different transfusion centers in Switzerland (Fribourg, Geneva, and Neuchatel). One hundred forty samples were recruited per center and per matrix, with a gender ratio of 50%, for a total of 420 HBD samples available per matrix. On both matrices, ferritin concentrations were quantified by three different laboratories using electrochemiluminescence (ECL), latex immunoturbidimetric assay (LIA), and luminescent oxygen channeling immunoassay (LOCI) assays, respectively. The degree of agreement between matrices and between the three sites/methods was assessed by Passing–Bablok and we evaluated the proportion of individuals deemed to have ID per method. Results. Overall, no difference between serum and heparinized plasma ferritin values was observed according to Passing–Bablok analyses (proportional bias range: 1.0–3.0%; maximum constant bias: 1.84 µg/L). Significant median ferritin differences (p < 0.001 according to Kruskal–Wallis test) were observed between the three methods (i.e., 83.6 µg/L, 103.5 µg/L, and 62.1 µg/L for ECL, LIA, and LOCI in heparinized plasma, respectively), with proportional bias varying significantly between ±16% and ±32% on serum and from ±14% to ±35% on plasma with no sign of gender-related differences. Affecting the lower end of RI, the proportion of ID per method substantially varied between 4.76% (20/420) for ECL, 2.86% (12/420) for LIA, and 9.05% (38/420) for LOCI. Conclusions. Serum and heparinized plasma are exchangeable for ferritin assessment. However, the order of magnitude of ferritin differences across methods and HBD recruitment sites could lead to diagnostic errors if uniform RI were considered. Challenging the recently proposed use of uniform ferritin thresholds, our results highlight the importance of method- and region-specific RI for ferritin due to insufficient inter-assay harmonization. Failing to do so significantly impacts ID diagnosis.

The blood donor population has great potential to serve as a sentinel system for the general population. The data presented in this study of a survey of the seroprevalence of Anti-SARS-CoV-2 antibodies in Switzerland are an illustrative example of this possibility. From March 2020 to January 2021, the increase in antibody seroprevalence for both Anti-NCP and Anti-S was only very moderate, up to ~17%. In May/June 2021, the Anti-NCP seroprevalence was 21.6% and the S-seroprevalence 59.4%, respectively, indicating only a moderate natural infection rate. The Anti-seroprevalence rate was in good agreement with the first vaccination campaign launched in winter 2020/21. The dramatic increase in the antibodies against the NCP protein (74.6%) since November/December 2021 to June–August 2022 was simultaneous with the appearance and rapid spread of the Omicron SARS-CoV-2 variant in Switzerland and the abolition of compulsory mask wearing in public spaces. At the end of 2022, 99.0% of the blood donor population already developed antibodies against the S protein and 83.9% against the NCP. One year later, after the official termination of the pandemic, these seroprevalences were even higher, 99.8% for the Anti-S and 95.0% for Anti-NCP. This increase for both of them was in accordance with the vaccination campaigns, the abolition of mask wearing, and the spread of the Omicron variant. These data show how the blood donor population can be used to represent the infection surveillance of the general population of a region or country.