The compound effect of irradiation and familial pseudohyperkalemia on potassium leak from red blood cells.

BACKGROUND: Familial pseudohyperkalemia (FP) is a rare asymptomatic condition characterized by an increased rate of potassium leak from red blood cells (RBC) on refrigeration. Gamma irradiation compromises RBC membrane integrity and accelerates potassium leakage. Here, we compared the effect of irradiation, applied early or late in storage, on FP versus non-FP RBC. STUDY DESIGN: Five FP and 10 non-FP individuals from the National Institute for Health Research Cambridge BioResource, UK, and three FP and six non-FP individuals identified by Australian Red Cross Lifeblood consented to the study. Blood was collected according to standard practice in each center, held overnight at 18-24°C, leucocyte-depleted, and processed into red cell concentrates (RCC) in Saline Adenine Glucose Mannitol. On Day 1, RCC were split equally into six Red Cell Splits (RCS). Two RCS remained non-irradiated, two were irradiated on Day 1 and two were irradiated on Day 14. RBCs were tested over cold storage for quality parameters. RESULTS: As expected, non-irradiated FP RCS had significantly higher supernatant potassium levels than controls throughout 28 days of storage (p < .001). When irradiated early, FP RCS released potassium at similar rates to control. When irradiated late, FP RCS supernatants had higher initial post-irradiation potassium concentration than controls but were similar to controls by the end of storage (14 days post-irradiation). No other parameters studied showed a significant difference between FP and control. DISCUSSION: FP does not increase the rate of potassium leak from irradiated RBCs. Irradiation may cause a membrane defect similar to that in FP RBCs.

Blood group A Secretors are associated with a higher risk of COVID-19 cardiovascular disease complications

The SARS-CoV-2 virus causes COVID-19, an infection capable of causing severe disease and death but which may also be asymptomatic or oligosymptomatic in many individuals. While several risk factors, including age, have been described, the mechanisms of this variation are poorly understood. Several studies have described associations between blood group and COVID-19 severity, while others do not. Expression of ABO glycans on secreted proteins and non-erythroid cells is controlled by a fucosyltransferase (FUT2). Inactivating mutations result in a non-secretor phenotype which is known to protect against some viral infections. We investigated whether ABO or secretor status was associated with COVID-19 severity. Data combined from healthcare records and laboratory tests (n=275) of SARS-CoV-2 PCR positive patients hospitalised with COVID-19, confirmed higher than expected numbers of blood group A individuals compared to O (RR=1.24, CI 95% [1.05,1.47], P=0.0111). There was also a significant association between group A and COVID-19-related cardiovascular complications (RR=2.56, CI 95% [1.43,4.55], P=0.0011) which is independent of gender. Molecular analysis of phenotype revealed that group A patients who are non-secretors are significantly less likely to be hospitalised than secretors. In a larger cohort of 1000 convalescent plasma donors, among whom the majority displayed COVID-19 symptoms and only a small minority required hospitalisation, group A non-secretors were slightly over-represented. Our findings indicate that group A non-secretors are not resistant to infection by SARS-CoV-2, but they are likely to experience a less severe form of its associated disease. Key PointsO_LIBlood group type A is associated with an increased risk of cardiovascular complications in COVID-19 patients. C_LIO_LIFUT2 "non-secretor" status reduces the risk of severe COVID-19 outcomes in patients with blood group A. C_LI