Sialidase treatment of rat-erythrocytes: a model for cellular aging?

An in vitro assay system was developed to test the propensity of "old" and sialidase-treated rat erythrocytes to be bound and phagocytosed by rat peritoneal macrophages. Cells considered to be old were phagocytosed to a greater degree than those considered to be young. When erythrocytes were treated with immobilized Vibrio cholerae sialidase, higher amounts of sialic acids had to be removed (25--30%) to induce binding and phagocytosis of the cells, than if the cells had been treated with soluble enzyme (9--15%).