Avian immunosenescence.

Immunosenescence, the aging of the immune system, is well studied in humans. Mammalian immune systems become less capable of fighting pathogens and individuals become more susceptible to infection and cancer in their elder years. Little is currently published on avian immunosenescence even though avian immune function has been well characterized and birds have been critical models in the study of immunology. The value of birds in the study of aging has been well established. Evidence demonstrates a decline in cell-mediated and (or) humoral immune function with age in four species: the barn swallow, collared flycatcher, ruff and Japanese quail. These studies suggest that birds may experience age-related changes in immune function similar to humans. Therefore, avian aging models should be evaluated for changes in immune function and comparisons made between short- and long-lived birds. Specifically, data on age-related changes in innate immunity are lacking for birds and should be characterized. These data will strengthen the use of avian models for the study of aging.