Eryptosis is a process by which mature erythrocytes can undergo self-destruction sharing several features with apoptosis. Premature programmed erythrocyte death may be induced by different agents. In this study, we compared mechanisms involved in two eryptotic models (oxidative stress and cell calcium overload) so as to distinguish whether they share signaling pathways and could be prevented by erythropoietin (Epo). Phosphatidylserine (PS) translocation and increased calcium content were common signs in erythrocytes exposed to sodium nitrite plus hydrogen peroxide or calcium ionophore A23187 (CaI), while increased ROS and decreased GSH levels were detected in the oxidative model. Protein kinase activation seemed to be an outstanding feature in eryptosis induced by oxidative stress, whereas phosphatase activation was favored in the CaI model. Cell morphology and membrane protein modifications were also differential signs between both models. Epo was able to prevent cell oxidative imbalance, thus blunting PS translocation. However, the hormone favored intracellular calcium influx which could be the reason why it could not completely counteract the induction of eryptosis. Instead, Epo was unable to inhibit PS externalization in the CaI model. The different mechanisms involved in the eryptotic models may explain the differential action of Epo upon erythrocytes induced to eryptosis by different agents.

Massive vaccination offers great promise for halting the global COVID-19 pandemic. However, limited supply and uneven vaccine distribution create an urgent need to optimize vaccination strategies. We evaluate SARS-CoV-2-specific antibody responses after Sputnik V vaccination of healthcare workers in Argentina, measuring IgG anti-spike titers and neutralizing capacity after one and two doses in a cohort of naïve or previously infected volunteers. By 21 days after receiving the first dose of vaccine, 94% of naïve participants develop spike-specific IgG antibodies. A single Sputnik V dose elicits higher antibody levels and virus neutralizing capacity in previously infected individuals than in naïve ones receiving the full two-dose schedule. The high seroconversion rate after a single dose in naïve participants suggests a benefit of delaying second dose administration to increase the number of people vaccinated. The data presented provide information for guiding public health decisions in light of the current global health emergency.