Age-related studies of SIg, Leu-4 and concanavalin A receptor densities and capping in human lymphocytes

We compared the cell surface antigen density and capping of three antigens in lymphocytes obtained from healthy, young (mean age 27 years) and elderly (mean age 76), population. There were no differences in the expression of surface immunoglobulin (SIg), concanavalin A (con A) receptors and Leu-4 antigen between the two groups. Kinetic analysis of these molecules revealed a slight decrease in capping in the older population, but the differences were not statistically significant. In order to test the possibility that subjecting the cells to metabolic stress might bring out the differences, we performed a kinetic analysis of SIg and con A capping in the presence of various concentrations of the metabolic inhibitor sodium azide. Although the capping in cells from elderly subjects was slightly more sensitive to azide, no statistical difference was found. Analysis of con A capping by a flow cytometric method yielded similar results, confirming the data obtained by visual capping experiments. We conclude that although a trend toward decreased capping was observed, there is little alteration in the surface molecule capping phenomenon in the age-groups studied.