Effects of PD-1 overexpression on function of elderly's T lymphocytes in inflammatory state

YUAN Jieming; LI Li; YUAN Weifeng; HUANG Wenjie

doi:10.13431/j.cnki.immunol.j.20170092

Abstract：This study performed to explore the correlation between the T lymphocytes' function and the expression of programmed cell death 1 receptor (PD-1) in old age.The subsets of T lymphocytes and the PD-1 expression of T lymphocytes in peripheral blood from 55 healthy youth (＜65 yr) and 55 healthy aged individuals (≥ 65 yr) in medical examination center of our hospital were determined by flow cytometry.The cell viability and the apoptosis ratio were respectively detected by CCK-8 assay and flow cytometry after in vitro blockade of the PD-1 pathway and stimulation with LPS;the concentration of TNF-α,IL-6,IL-10,IL-2 and IFN-γ in the culture supernatant were measured by ELISA.Compared with the healthy youth,the absolute numbers of T lymphocyte subsets were markedly lower,and the PD-1 expression level of T lymphocytes was significant higher in the healthy aged individuals (P＜0.05).The blockade of PD-1 increased the cell viability of T lymphocytes and reduced the apoptosis of T lymphocytes in the healthy aged individuals (P＜0.05).There were no significantly difference in cell viability and apoptosis of T lymphocytes between LPS+anti-PD-1 group and LPS group in the healthy youth.The level of TNF-α in the healthy aged individuals was lower than that in the healthy youth (P＜0.05),and the IL-10/TNF-α ratio in the healthy aged individuals was higher than that in the healthy youth (P＜0.05).These results indicate that the function of elderly's T lymphocytes in the inflammatory state is closely correlated with the PD-1 overexpression.The increased secretion of suppressive cytokines with the immune response could be more likely to develop immunosuppression,which might relate to more susceptibility to infectious diseases resulting in increased morbidity and mortality of aged individuals.