Abstract
Activated T cells from elderly humans are known to often display a decline in interleukin-2 (IL-2) production. However, the possible effects of aging on the expression of IL-2 receptor (IL-2R) subunits by human T cells are more controversial and less well characterized. In the present investigation, the surface expression of IL-2Rα, IL-2Rβ, and IL-2Rγ subunits on resting and activated T cells from 15 sets of elderly and young humans was evaluated. The results showed no significant differences in the average expression of IL-2Rα, IL2Rβ, and IL-2Rγ on resting T cells from elderly and young subjects, with values of 10% or less. Similarly, no significant differences were found in the mean levels of IL-2Rα, IL-2Rβ, and IL-2Rγ on T cells from elderly and young subjects stimulated with anti-Ig cross-linked anti-CD3 (monoclonal antibody [mAb] OKT3), phorbol myristate acetate (PMA), anti-CD3 and PMA, or 1% phytohemagglutinin (PHA) plus PMA. Analyses of the expression of IL-2R on activated T cells from elderly people revealed a marked heterogeneity in IL2R levels irrespective of the stimuli. Other experiments showed that the age-related alterations in surface expression of IL-2Rα were not correlated to changes in the release of soluble IL-2Rα. Age-related changes in IL-2R expression on activated T cells from individual donors were not coupled to the ability of the T cells to undergo G1/S progression. Collectively, these observations suggest that activated T cells from elderly people exhibit substantial heterogeneity in the expression of IL-2R subunits and that alterations in IL-2R expression may be distinct from intrinsic defects in G1/S progression and proliferative responses.
Get full access to this article
View all access options for this article.