Increased percentages of regulatory T cells are associated with inflammatory and neuroendocrine responses to acute psychological stress and poorer health status in older men and women

Rationale: The percentage of regulatory T cells (T_Regs) - a subtype of T lymphocyte that suppresses the immune response - appears to be reduced in a number of stress-related diseases. The role of the T_Reg in stress-disease pathways has not yet been investigated. Objectives: The aim of the study was to investigate the association between biological responsivity to acute psychosocial stress and the percentage of T_Regs in healthy older adults. The secondary purpose was to measure the associations between T_Reg percentage and psychological and physical well-being in the participants. Methods: Salivary cortisol and plasma interleukin (IL)-6 samples were obtained from 121 healthy older men and women from the Whitehall II cohort following acute psychophysiological stress testing. Three years later at a follow-up visit, we measured T_Reg percentages and psychological and physical well-being were recorded using the Short Form 36 Health Survey and the Center for Epidemiologic Studies Depression Scale. Results: Blunted cortisol responses (p = 0.004) and elevated IL-6 responses (p = 0.027) to acute psychophysiological stress were associated with greater T_Reg percentage independently of age, sex, BMI, smoking status, employment grade, time of testing, and baseline measures of cortisol and IL-6, respectively. Percentage of T_Regs was associated cross-sectionally with lower physical (p = 0.043) and mental health status (p = 0.008), and higher levels of depressive symptoms (p = 0.002), independently of covariates. Conclusions: Increased levels of T_Regs may act as a defence against increased inflammation and may be a pre-indication for chronically stressed individuals on the cusp of clinical illness.