Apoptosis and red blood cell echinocytosis: common features.

Apoptosis of nucleated blood cells induced by oxidants and/or reactive oxygen species is accompanied by the typical membrane pathology. Meanwhile, red blood cell (RBC) membrane is a popular object for studying appropriate cytotoxic effects. Scanning electron microscopy provides a reliable tool for detecting the oxidative changes in RBC shape and size. Transition of normal discoid erythrocytes to crenated forms (echinocytes) is often induced by the same factors which cause apoptosis of blood cells, e.g., ionizing radiation and other reactive oxygen intermediate-inducing agents, exogenous oxidants, in vitro aging conditions, cytosolic calcium increase, etc. Moreover, the biochemical membrane alterations in oxidant-induced echinocytosis is strongly reminiscent of the changes associated with apoptosis, e.g., cell shrinkage, lipid oxidation, energy depletion and loss of transmembrane lipid asymmetry. Hence, characteristic changes in cell shape in oxidant-treated RBCs are of value for interpreting the membrane alterations occurring in leukocyte apoptosis.