Effects of psychological stress on skin immune function: Implications for immunoprotection versus immunopathology

Psychological stress can have bidirectional effects on immune function, being immunosuppressive under certain conditions but immunoenhancing under others. Chronic stress (lasting for weeks, months, or years) is known to suppress or dysregulate immune function. Acute stress (lasting for minutes to hours) has been shown to enhance immune function, particularly in the skin. Acute stress experienced at the time of immune activation or antigen exposure significantly enhances primary/innate or secondary/adaptive immune responses. Acute stress induces a redistribution of leukocytes from the blood to compartments like the skin and sentinel lymph nodes, and this redistribution is thought to be one important mediator of the immunoenhancing effects of acute stress. The studies described here may provide substrates for interventions that could be designed to ameliorate stress-induced exacerbation of allergic, inflammatory, or auto-immune diseases. These studies also provide the framework for developing therapeutic interventions that may harness the body's endogenous adjuvant-like immunoenhancing mechanisms to enhance protective immunity during vaccination, infection, or wound healing.