ANTARCTIC ISOLATION - IMMUNE AND VIRAL STUDIES

Stressful environmental conditions ape a major determinant of immune r eactivity. This effect is pronounced in Australian National Antarctic Research Expedition populations exposed to prolonged periods of isolat ion in the Antarctic. Alterations of T cell function, including depres sion of cutaneous delayed-type hypersensitivity responses and a peak 4 8.9% reduction of T cell proliferation to the mitogen phytohaemaggluti nin, were documented during a 9-month period of isolation. T cell dysf unction was mediated by changes within the peripheral blood mononuclea r cell compartment, including a paradoxical atypical monocytosis assoc iated with altered production of inflammatory cytokines. There was a s triking reduction in the production by peripheral blood mononuclear ce lls of the predominant pro-inflammatory monokine TNF-alpha and changes were also detected in the production of IL-1, IL-2, IL-6, IL-1ra and IL-10. Prolonged Antarctic isolation is also associated with altered l atent herpesvirus homeostasis, including increased herpesvirus sheddin g and expansion of the polyclonal latent Epstein-Barr virus-infected B cell population. These findings have important long-term health impli cations.