Studies on the mechanism of erythrocyte aging and destruction II. Membrane fragmentation in rat erythrocytes after in vitro treatment with lysophosphatides: Scanning electron microscope studies

Abstract

Rat red blood cells of differing ages were separated according to density by Ficoll gradient centrifugation. Cells from the top, middle and bottom fractions were incubated with sublytic concentrations of lysophosphatidylethanolamine (LPE) or lysophosphatidylcholine (LPC). The surface transformations of these red cells were observed with a scanning electron microscope. In the presence of low concentrations of LPE, normal red blood cells with their characteristic biconcave-disc shape become irregular with large bulges on the surface. As the concentrations of LPE increase these bulges elongate as pseudopod-like protuberances which transform into narrow spicules. A small globular tip forms at the end of each spicule as a result of the pinching-in of the membrane. Continuing constriction leads to the detachement of the small fragment at the tip and membrane fragmentation occurs. Microfragmentation of the red cell membrane induced by LPE or LPC is an irreversible phenomenon. In the presence of a given concentration of LPE, the red cells from the top fractions of the Ficoll gradient are more resistant than cells from the middle fractions; cells from these latter fractions are in turn more resistant than those from the bottom fractions of the gradient. The sequence of membrane transformation produced by lysophosphatides in vitro can satisfactorily explain most of the in vivo age-dependent changes found in red blood cells.