Background: Several factors contribute to the manifestation of red blood cell (RBC) storage lesions, with one of the most interesting being the "donor variation effect". Since many haematological characteristics of blood donors are sex-dependent, sex hormones and their age-dependent variation may affect the storage profile of RBCs.
Materials and methods: Fresh blood from 200 healthy male and female donors underwent haematological, biochemical and physiological analysis. Three selected groups of donors (men, n=8; pre-menopausal women, n=8; and post-menopausal women, n=4) exhibiting as similar as possible baseline values were recruited for blood donation in leukoreduced CPD/SAGM units. RBC indices, haemolysis and propensity for haemolysis, reactive oxygen species (ROS) and plasma antioxidant capacity were measured bi-weekly.
Results: Female blood was characterised by lower plasma antioxidant capacity and free haemoglobin (Hb) levels in vivo, in spite of the higher RBC osmotic fragility, compared to male blood. Comparatively low Hb concentration was also measured in stored RBCs from female donors, as in vivo. Mean corpuscular Hb (MCH), mean corpuscular Hb concentration (MCHC), and plasma antioxidant capacity were also lower in female donors throughout storage, even though baseline levels were equal to those of the male group. There was no difference in propensity of stored RBCs for haemolysis between male and female units but intracellular ROS levels were significantly lower in female RBCs. Increased end-of-storage extracellular potassium and recruitment of protein stress markers (clusterin, Hb) to the RBC membrane were observed in the units of post- vs pre-menopausal female donors at mid-storage onwards.
Discussion: Donor's sex has an impact on Hb concentration and redox parameters of stored RBCs. In addition, menopause seems to promote RBC membrane remodelling, at least during prolonged storage. Our pilot study provides new insights on the different effects on RBC storage lesion according to sex.