Binding of anti-spectrin antibodies to red blood cells and vesiculation in various in vivo and in vitro ageing conditions in the rat

In this study, the binding of naturally occurring antibodies as well as of induced anti-spectrin antibodies to red blood cells (RBC), in relation with different ageing conditions, was investigated in the rat. RBC from aged animals, or from rats whose RBC were age-induced either by means of hypertransfusion (which blocks erythropoiesis) or by treatment with clodronate-containing liposomes (which reduces RBC removal from circulation), were used. Attainment of RBC ageing was demonstrated by MCV reduction and by an increase of both RBC density and 4.1a/4.1b RBC membrane protein ratio. The results demonstrate an augmented anti-spectrin antibody binding to RBC in relation with their ageing condition, especially when induced by hypertransfusion. The vesiculation process was also investigated and correlated with antibody binding: vesicles were found only in the plasma of clodronate-treated rats, whose RBC showed the lowest level of anti-spectrin antibody binding with respect to the other groups. In addition, RBC preserved in vitro in different media showed a binding of anti-spectrin antibody, which inversely correlated with the vesiculation process. On the whole, the latter results suggest a protective effect of vesicles towards IgG opsonization of aged RBC.