Evidence for a shift in the Th-1 to Th-2 cytokine response associated with chronic stress and aging

Abstract

Background: A number of studies have shown that the chronic stress of caring for persons with dementia can have significant immunological consequences as demonstrated by the down-regulation/dysregulation of the cellular immune response.

Methods: Utilizing flow cytometry to measure the percentages and absolute numbers of CD-4(+) and CD-8(+) T lymphocytes producing the cytokines indicative of Th-1, Tc1 and Th-2, and Tc2 cells, we compared spousal caregivers and control subjects. The expression of interleukin-2 (IL-2), interferon gamma (IFN-gamma), and interleukin-10 (IL-10) in the cytoplasm of CD-4(+) and CD-8(+) lymphocytes was assessed.

Results: Neither stress nor age was significantly related to the percentage or number of IFNgamma(+)/CD-8(+), IL-2(+)/CD-8(+) cells, or IFNgamma(+), IL-2(+), CD-4(+) cells. However, the percentage of IL-10(+) cells was higher in lymphocytes obtained from caregivers than control subjects. In addition, the significant interaction between stress and aging for IL-10(+)/CD-4(+) and IL-10(+)/CD-8(+) cells demonstrated that the difference between caregivers and control subjects was age dependent; the difference between caregivers and control subjects was substantially larger in younger individuals than in older individuals.

Conclusions: The data are consistent with previous reports on acute stress and suggest that there may also be a shift from a Th-1 to a Th-2 response associated with a chronic stressor such as caregiving. This shift could have implications for an individual's responses to pathogens.