Effects of age on immune function - Development and senescence.

PALACIOS, M. G.

Portland, Oregon, EEUU

Congreso; 125th meeting of the American Ornithologists’ Union; 2008

American Ornithologists’ Union

Changes in immune function with age are well described for humans and model organisms, but little understood for free-living animals. I assessed various components of immune function in nestling and adult tree swallows and confirmed that nestlings have a more immature immune system than young adults. Among adults (1 to 8 years old), I found no evidence of immunosenescence in innate immunity or B-lymphocyte function, but older individuals showed deterioration of T-lymphocyte function. To assess the consequences of this aging pattern I performed a field experiment to test the hypothesis that older, immunosensecent individuals pay higher costs of defense against pathogens than young ones. I simulated a pathogenic insult by challenging adults with a bacterial component and monitored changes in their parental behavior, body mass, hormonal and immunological parameters, reproductive success, and survival. As predicted, older birds lost more body mass than young ones despite their greater reduction in parental care. Physiological and fitness-related parameters are currently under analysis.  This research on sickness responses and their fitness consequences are important contributions to the fields of ecological immunology and disease ecology.