The age-dependent cytokine production by murine CD8(+) T cells as determined by four-color flow cytometry analysis

Flow cytometry has been used to simultaneously examine;intracellular cytoki ne production and expression of CD44 and CD45RB by marine CD8(+) T cells de rived from young (2-3 months) or aged (18-22 months) mice. Cytokine product ion by aged CD8(+) T cells differs from that by CD8(+) T cells derived from young animals in that a significantly higher percentage of the aged can he triggered to produce interleukin (IL)-4, interferon (IFN)-gamma, and tumor necrosis factor alpha(TNF alpha). Conversely, a greater fraction of young CD8(+) T cells produce IL-2. Aged mice nor only hare a higher percentage of CD8(+)/CD44(hi) T cells, but also a larger fraction of these cells me IFN- y(+) and IL-4(+), while a lower fraction me IL-2(+) than is observed in you ng CD8(+)/CD44(hi) Teens. In terms of relative contribution to total cytoki ne synthesis, a great fraction of CD8(+) T cells reduce IFN-gamma and IL-4 than in CD4(+) T cells, whereas CD4(+) T cells are the major producers of I L-2.