Comparison between serum interleukin-2 concentrations in healthy adult and elderly subjects

Impact of psychological and endocrine factors on cytokine production of healthy elderly people

Human ageing has been associated with immunological changes including blunted T-cell responses and increased production of pro-inflammatory cytokines. Here, we investigated the role of psychological and endocrine factors in the production of pro-inflammatory cytokines (tumor necrosis factor-alpha and interleukin (IL)-6) as well as soluble IL-2Ralpha, associated with T-cell activation. Forty-six elderly subjects (60-91 yrs) and 33 young adults (20-40 yrs) were recruited accordingly the SENIEUR protocol. The emotional status was measured by structured clinical interviews. Salivary cortisol levels (9, 12 and 22 h) and serum dehydroepiandrosterone (DHEA) were assessed by radioimmunoassays. The elderly were more stressed, depressed and anxious than the young subjects. Cortisol levels were increased whereas DHEA levels were significantly reduced in the elderly. Both groups showed equivalent production of pro-inflammatory cytokines as well as soluble IL-2Ralpha. Psychological scores were positively correlated to evening cortisol levels and negatively correlated to morning DHEA levels. No relationships were noted between psychological factors and cytokines studied. However, evening cortisol levels were found positively correlated to TNF-alpha and sIL-2Ralpha levels. These data indicate that healthy ageing is associated with significant distress and activation of the hypothalamic-pituitary-adrenal axis. Our data also suggest that there are complex psychoneuroendocrine relationships involved with cytokine production during ageing.

Age-related differences in cell-specific cytokine production by acutely ill Malawian patients

Age-related changes in human cell-specific cytokine responses to acute illness have not been well examined. We therefore evaluated age-related differences in T, B and natural killer (NK) peripheral blood lymphocyte cytokine responses of 309 acutely ill hospitalized people in Malawi, Africa, < 1 month-61 years of age. We used four-colour flow cytometry and performed Wilcoxon rank sum and Kruskal-Wallis tests, Pearson (rp) and Spearman (rs) correlations, and linear and logistic regression analyses to control for human immunodeficiency virus infection (HIV) status, the percentages of lymphocytes expressing CD4, and the nature of the acute infection. The percentages of CD8- and CD8+ T cells producing induced IL-8 decreased with age (rs = -0.44 and -0.53). The percentages of T cells producing TNF-alpha were higher, and the percentages producing IL-10 were lower, in those > or =13 than those < 13 years old (medians: 17.7 versus 10.5 and 1.4 versus 3.0, respectively). The percentages of CD8- T cells producing IFN-gamma were higher and stable in those > or =1 year old compared to infants (medians: 23.5 versus 10.4); the percentages of NK producing IFN-gamma were higher post-infancy and then declined to relatively low levels with increasing age. The percentages of T cells producing IL-2 were highest in those 5- <31 years old (median 5.6) and lowest in those > or =31 years old (median 1.9). The ratios of the percentages of T cells producing IL-4 to those producing IL-8 and to those producing IL-10 both increased with age. These data suggest that innate immunity, represented by NK IFN-gamma production, dominates in early life. A number of shifts occur after infancy and before adolescence, including a proinflammatory shift from IL-8 to TNF-gamma and a type 2 shift from IL-10 to IL-4 dominance. These findings suggest distinct age-related differences in the human response to acute illness and may be useful in directing future efforts at immunomodulatory therapies.