Senescent erythrocytes: Modification of rheologic properties, antigenic expression and interaction with monocytes

Human erythrocytes have a well-defined lifespan of 120 days. Their eventual removal from circulation is a complex process affected by many cellular pa rameters, making them susceptible to sequestration in the spleen and other organs. The purpose of this study was to investigate putative changes in rh eologic properties, antigenic expression and interaction with monocytes of senescent erythrocytes (SE). SE and young erythrocyte (YE) fractions were o btained by differential centrifugation from 20 healthy donor blood samples. Membrane rheomechanic properties (by difractometric method), ABO and MN an tigens reactivity and erythrophagocytosis by peripheral monocytes were inve stigated in each fractions. SE showed a little decrease in the deformabilit y index and an increase of both membrane elastic modulus and surface viscos ity. The studies performed indicate a decreased expression in the antigens of both blood group systems studied (p < 0.01) and an increased rate of ery throphagocytosis by monocytes in SE compared to YE (p < 0.01). The signific ant modifications in the biomechanic properties of senescent red blood cell membrane and the loss of antigenic expression could lead to physiological phagocytosis.