Conclusions
Aging may have a robust effect on the response of PBMCs towards hPDLSC-induced immunosuppression.
Methods
PBMCs were collected from younger (16-19 years) and older (45-55 years) donors, then co-cultured with confirmed hPDLSCs for various lengths of time. T lymphocyte proliferation and cell surface marker expression were analyzed by flow cytometry. Cytokine expression levels were measured by quantitative polymerase chain reaction assays and enzyme-linked immunosorbent assays.
Results
CD28 expression by T lymphocytes decreased with age, indicating reduced proliferation; CD95 expression increased with age, indicating enhanced apoptosis. Moreover, hPDLSCs inhibited T lymphocyte proliferation in both age groups; this inhibition was stronger in cells from older donors than in cells from younger donors. Age reduced the secretion of interleukin-2 and interferon-γ, whereas it increased the secretion of tumor necrosis factor-β by PBMCs cultured with hPDLSCs. Conclusions: Aging may have a robust effect on the response of PBMCs towards hPDLSC-induced immunosuppression.