Is ageing associated with a shift in the balance between Type 1 and Type 2 cytokines in humans?

The balance between Type 1 and Type 2 cytokines is important for the outcome of several infectious diseases. As elderly humans show increased morbidity and mortality from infectious diseases, this study tests if ageing is associated with a change towards Type 2 dominance in T cells. Expression of IFN-γ, and IL-4 was measured in CD4⁺ and CD8⁺ T cells by flow cytometry in three groups: young controls (n = 28), 81-year-olds (n = 22), and centenarians (n = 25). The major findings were that the percentage of IFN-γ⁺ as well as IL-4⁺ T cells was increased in aged subjects. Furthermore, after adjusting for decreased lymphocyte counts in the elderly, the concentration in the blood of IFN-γ⁺ and IL-4⁺ CD8⁺ T cells was still increased in the 81-year-olds. In centenarians, a shift towards a relative dominance of Type 2 cytokine expression was found within CD8⁺ T cells. Furthermore, the percentage of T cells with cytokine expression was closely correlated to the in vivo expression of CD95 and CD45RO. In conclusion, we found some evidence for an age-related shift towards a Type 2 cytokine profile.