The role of Ca2+-dependent biochemical changes in the ageing process in normal red cells and in the development of irreversibly sickled cells.

During the ageing process of normal red cells and in the formation of irreversibly sickled cells (ISCs) there is a progressive increase in the intracellular concentration of Ca2+. This is parallelled by the development of a variety of morphological and biochemical changes in older fractions of normal cells and in ISCs which are similar to those seen in normal cells exposed to Ca2+ ionophore. These changes include cell shrinkage, loss of membrane lipid and degradation of cytoskeletal proteins and polyphosphoinositides. In this paper we consider the ways in which the Ca2+-dependent biochemical changes may be related to the morphological alterations which are characteristic of ageing and irreversible sickling.