Decreased proliferation, interleukin 2 synthesis, and interleukin 2 receptor expression are accompanied by decreased mRNA expression in phytohemagglutinin-stimulated cells from elderly donors.

Using cDNA probes to human interleukin 2 (IL2) and interleukin 2 receptor (IL2R), the amount of IL2 and IL2R mRNA produced by PHA stimulated peripheral blood mononuclear cells from young (less than 40 yr) and old (greater than 60 yr) donors was quantitated. Stimulated cell cultures from each individual were also examined for proliferative ability, expression of membrane IL2R, membrane IL2R density, and for the amount of IL2R shed into the culture supernatant. Induction of IL2 and IL2R mRNAs were decreased in cells from elderly individuals, as were the levels of IL2 secretion, the percentage of IL2R+ T cells and the density of membrane IL2R per cell. The results suggest that decreased expression of both IL2 and IL2R mRNA contributes to the low synthesis of IL2 and membrane IL2R, respectively, and is partially responsible for the diminished proliferative activity observed in lymphocytes from the elderly.