Age‐associated E pstein– B arr virus‐specific T cell responses in seropositive healthy adults

Summary E pstein– B arr virus ( EBV ) is present in 95% of the world's adult population. The immune response participates in immune vigilance and persistent infection control, and this condition is maintained by both a good quality (functionality) and quantity of specific T cells throughout life. In the present study, we evaluated EBV ‐specific CD 4 + and CD 8 + T lymphocyte responses in seropositive healthy individuals younger and older than 50 years of age. The assessment comprised the frequency, phenotype, functionality and clonotypic distribution of T lymphocytes. We found that in both age groups a similar EBV ‐specific T cell response was found, with overlapping numbers of tumour necrosis factor ( TNF )‐α + T lymphocytes ( CD 4 + and CD 8 + ) within the memory and effector cell compartments, in addition to monofunctional and multi‐functional T cells producing interleukin ( IL )‐2 and/or interferon ( IFN )‐γ. However, individuals aged more than 50 years showed significantly higher frequencies of IL ‐2‐producing CD 4 + T lymphocytes in association with greater production of soluble IFN ‐γ, TNF ‐α and IL ‐6 than subjects younger than 50 years. A polyclonal T cell receptor ( TCR )‐variable beta region (V β) repertoire exists in both age groups under basal conditions and in response to EBV ; the major TCR families found in TNF ‐α + / CD 4 + T lymphocytes were V β1, V β2, V β17 and V β22 in both age groups, and the major TCR family in TNF ‐α + / CD8 + T cells was V β13·1 for individuals younger than 50 years and V β9 for individuals aged more than 50 years. Our findings suggest that the EBV ‐specific T cell response (using a polyclonal stimulation model) is distributed throughout several T cell differentiation compartments in an age‐independent manner and includes both monofunctional and multi‐functional T lymphocytes.