Background: To examine the impact of chronic psychological stress on the immune system, a series of cellular and humoral immunological parameters was compared in 18 female caregivers of handicapped people and 18 age- and sexmatched controls. Methods: The immunological parameters included assessment of T cell number (T cells, T helper, and T suppressor/cytotoxic) and function (delayed-type cutaneous hypersensitivity), antibody titers for latent herpesviruses (cytomegalovirus and herpes simplex virus 1 and 2), and markers of inflammation (complement C3 and C4 factors and c-reactive protein). Serum immunoglobulins (IgG, IgM, IgA, IgE) and titers for the nonlatent virus roseola were used to control for nonspecific elevations in serum proteins. Results were associated with the age of the investigated subjects, the severity of stress (family burden) and the degree of disability of the handicapped people. Results: Caregivers had a significantly lower percentage of T cells, a significantly higher percentage of T suppressor/cytotoxic cells and a significantly lower T helper:suppressor ratio. Subjects were also analyzed after division into two groups according to the median age (45 years). Compared to their matched controls, older caregivers (mean age = 50.3) also had lower numbers of T cells and T helper cells and higher antibody titers for cytomegalovirus. In addition, in the caregiver population severity of stress was significantly positively correlated with T suppressor/cytotoxic cells and negatively correlated with T helper:suppressor ratio. No other differences in the immune parameters were found between caregivers and controls. Conclusions: The results indicate that psychological stress differentially affects various aspects of the immune system and confirm the relevant role of age and severity of stress in modulating these influences.
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