Publication
Cytomegalovirus Exposure in the Elderly Does Not Reduce CD8 T Cell Repertoire Diversity
Publisher:
The American Association of Immunologists
Date:
15-01-2019
DOI:
10.4049/JIMMUNOL.1800217
Abstract: With age, the immune system becomes less effective, causing increased susceptibility to infection. Chronic CMV infection further impairs immune function and is associated with increased mortality in the elderly. CMV exposure elicits massive CD8+ T cell clonal expansions and diminishes the cytotoxic T cell response to subsequent infections, leading to the hypothesis that to maintain homeostasis, T cell clones are expelled from the repertoire, reducing T cell repertoire ersity and diminishing the ability to combat new infections. However, in humans, the impact of CMV infection on the structure and ersity of the underlying T cell repertoire remains uncharacterized. Using TCR β-chain immunosequencing, we observed that the proportion of the peripheral blood T cell repertoire composed of the most numerous 0.1% of clones is larger in the CMV seropositive and gradually increases with age. We found that the T cell repertoire in the elderly grows to accommodate CMV-driven clonal expansions while preserving its underlying ersity and clonal structure. Our observations suggest that the maintenance of large CMV-reactive T cell clones throughout life does not compromise the underlying repertoire. Alternatively, we propose that the diminished immunity in elderly in iduals with CMV is due to alterations in cellular function rather than a reduction in CD8+ T cell repertoire ersity.