ABSTRACT
OBJECTIVE: Caregiving for a spouse with Alzheimer's disease is associated with alterations in various immune cell responses. Chemotaxis of immune cells to chemokines is an important factor involved in lymphocyte migration, which plays an essential role in inflammatory responses to infection and may also be involved in atherogenesis. However, the effects of chronic stress on chemotaxis have not been investigated. The objective of this study was to examine lymphocyte chemotaxis to chemokines, stromal cell-derived factor-1 (SDF-1), N-formyl-methionyl-leucyl-phenylalanine (FMLP), and a beta-adrenergic agonist, isoproteronol (ISO), in response to an acute stressor in Alzheimer's caregivers. Correlations between immune cell chemotaxis and epinephrine and norepinephrine levels were also examined. METHODS: Caregivers (n = 18) and noncaregiver controls (n = 9) completed a public speaking task. Blood was drawn before and immediately after the task for changes in chemotaxis to FMLP, SDF-1, and ISO, and for epinephrine and norepinephrine levels. RESULTS: Caregivers had reduced chemotaxis to FMLP, SDF-1, and ISO in response to the speech task, compared with non-caregivers. Also, the direction of the correlations between chemotaxis to FMLP, SDF-1, and ISO and epinephrine levels differed between groups. CONCLUSIONS: These findings suggest that immune cells released into circulation in response to acute stress are altered in caregivers. Group differences in immune responses may be due to sympathetically mediated alterations, which may have implications for caregivers' ability to successfully mount viable immune responses, as well as, atherogenesis.
