ALTERED EXPRESSION OF VARIOUS RECEPTORS ON T-CELLS IN YOUNG AND OLD MICE AFTER MITOGENIC STIMULATION - A FLOW CYTOMETRIC ANALYSIS

To understand mechanism underlying the age-related impairment of T cel l functions, changes in the expression of cell surface receptors were examined in T cells after mitogenic stimulation by flow cytometry and results were compared between young and old mice. Before stimulation, no significant difference was observed in the density of TCR alpha bet a, CD3, CD122 (IL-2R beta), IL-2R gamma, CD28 and CD95 (Fas) of T cell s between young and old mice. As for CD25(IL-2R alpha) and CTLA-4, rel ative intensity and percentage of positive cells were higher in old th an in young mice, although the levels were low compared with those aft er stimulation. After mitogenic stimulation, increased expression of t he density was observed in CD25, IL-2R beta, IL-2R gamma, CD28, CTLA-4 and CD95 and the magnitude of increase was more pronounced in T cells from young than those from old mice. The expression of TCR alpha beta and CD3 decreased after mitogenic stimulation, and the degree of expr ession quickly recovered to the initial level in young mice, but not i n old mice. Lower expression of TCR, IL-2 receptors and co-stimulatory molecules in T cells from old mice could be responsible for the impai red proliferation after mitogenic stimulation. (C) 1997 Elsevier Scien ce Ireland Ltd.