Predominant expression of the immunosenescent biomarker CD57 on CD4+ T cells and their subsets in the older people associating with the cardiovascular disease risk factors

CD57 is one of the biomarkers for immunosenescence, and its expression increases with age. This study aimed to analyze CD4+ T cell phenotypes and cytokine production (interferon-gamma [IFN-γ] and interleukin [IL]-17) and their association with cardiovascular disease (CVD) risk factors. Using multi-color flow cytometry, leftover whole blood specimens from 53 older people (≥ 60 years) and 42 young individuals (≤ 35 years) were analyzed. We found that older individuals had significantly higher percentages of CD4+CD57+ and CD4+CD28- T cells than the younger group. Notably, CD57 expression was positively correlated with the number of CD4+CD28- T cells. Among the participants, older individuals with ≥ 1 CVD risk factor (dyslipidemia [DL] and/or hypertension [HT] and/or diabetes mellitus [DM]) had the highest median values of CD4+CD57+, CD4+CD28-, and CD4+CD28-CD57+ T cells. Comparing the CD57+ and CD57- populations, the median percentage of IFN-γ and IL-17 from CD4+CD57+ T cells were significantly higher than those from CD4+CD57- T cells. Interestingly, older participants with ≥ 1 CVD risk factor displayed a significantly higher percentage of IFN-γ-producing CD4+CD57+ T cells than older and young individuals without CVD risk factors. In conclusion, this work reports prominent CD57 expression on CD4+ T cells and their subsets in older people. Increasing age, along with CVD risk factors, may participate to alterations in immune function, reflected by higher levels of IFN-γ- and IL-17-producing CD4+CD57+ T cells, and may be associated with an elevated level of chronic low-grade inflammation.