Changes in some properties and functions of plasma membranes of macrophages from young, adult and aged mice.

We studied age-dependent changes in distribution of receptor-ligand complexes in the lateral plain of plasma membrane after binding of six different lectins and anti H-2a and anti Ias antisera to the surface of mouse peritoneal macrophages. Additionally we examined formation of spontaneous rosettes with sheep red blood cells and the phagocytic and pinocytic activities of these macrophages. Macrophages of young and aged mice exhibited a lower mobility of the studied antigens and lectin receptors (determined as a function of patch and cap formation) and a higher rate of formation of spontaneous rosettes. The percentage of Ia antigens bearing macrophages was very low during early ontogenesis; it increased during adulthood and decreased during ageing. The highest percentage of phagocytizing macrophages was found in adult mice, even thought the phagocytic index (i.e., the average quantity of phagocytized particles in a phagocytizing cell) kept increasing during postnatal life. However, the level of pinocytosis was the same in all three groups.