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

Background. A number of studies have shown that the chronic stress of carin g for persons with dementia can have significant immunological consequences as demonstrated by the down-regulation/dysregulation of the cellular immun e response. Methods. Utilizing flow cytometry to measure the percentages and absolute n umbers of CD-4(+) and CD-8(+) T lymphocytes producing the cytokines indicat ive of Th-1, Tc1 and Th-2, and Tc2 cells, we compared spousal caregivers an d control subjects. The expression of interleukin-2 (IL-2), interferon gamm a (IFN-gamma), and interleukin-10 (IL-10) in the cytoplasm of CD-4(+) and C D-8(+) lymphocytes was assessed. Results. Neither stress nor age was significantly related to the percentage or number of IFN-gamma (+)/CD-8(+), IL-2(+)/CD-8(+) cells, or IFN gamma (), IL-2(+), CD-4+ cells. However, the percentage of IL-10(+) cells was high er in lymphocytes obtained from caregivers than control subjects. In additi on, the significant interaction between stress and aging for IL-10(+)/CD-4( +) and IL-10(+)/CD-8(+) cells demonstrated that the difference between care givers and control subjects was age dependent; the difference between careg ivers 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 a ssociated with a chronic stressor such as caregiving. This shift could have implications for an individual's responses to pathogens.