Numerical and functional alterations of circulating γδ T lymphocytes in aged people and centenarians

The aim of this study was to evaluate the peripheral representation, in vitro expansion, cytokine production, and cytotoxicity of γδ T lymphocytes from 104 healthy subjects ranging in age from 19 to 103 years. We demonstrated that the absolute number of circulating γδ+ T cells was reduced significantly in old people and centenarians in comparison with young subjects as a consequence of the age-related decreased lymphocyte number. The decrease was a result of an age-dependent reduction of Vδ2 T cells, whereas the absolute number of Vδ1 T cells was unaffected by age. As a consequence, the Vδ2/Vδ1 ratio was inverted in old subjects and centenarians. A higher percentage of γδ+ T cells producing tumor necrosis factor α was found in old donors and centenarians, whereas no age-related difference was observed in interferon -γ production. After a 10-day in vitro expansion, a twofold lower expansion index of γδ T cells, and particularly of a Vδ2, but not of a Vδ1 subset, was found in old people and centenarians in comparison with young subjects. The cytotoxicity of sorted γδ T cells was preserved in old people and centenarians. The alteration of γδ T cells could contribute to the age-related derangement of T cell-mediated, adoptive responses and may represent a new characteristic of immunosenescence.