Alterations in the expression of interleukin-2R subunits by activated T cells from elderly humans are uncoupled from aberrancies in G1/S progression.
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-2Ralpha, IL-2Rbeta, and IL-2Rgamma 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-2Ralpha, IL2Rbeta, and IL-2Rgamma 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-2Ralpha, IL-2Rbeta, and IL-2Rgamma 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-2Ralpha were not correlated to changes in the release of soluble IL-2Ralpha. 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 G(1)/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 G(1)/S progression and proliferative responses.
Ginn-Pease
M E
ME
Departments of Medical Biochemistry and Internal Medicine, The William H. Davis Medical Research Center, The Ohio State University, Columbus, OH 43210-1228.
Whisler
R L
RL
D000328:Adult; D000368:Aged; D000375:Aging / Q000276:immunology* / Q000378:metabolism; D002453:Cell Cycle / Q000276:immunology; D002478:Cells, Cultured; D006801:Humans; D008213:Lymphocyte Activation / Q000276:immunology*; D008875:Middle Aged; D015375:Receptors, Interleukin-2 / Q000096:biosynthesis*; D012995:Solubility; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism*
D015375:Receptors, Interleukin-2