Influenza A Virus‐Specific Cytotoxic T Lymphocyte Activity Declines with Advancing Age

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Abstract
To investigate whether influenza A-specific cytotoxic T lymphocyte (CTL) activity is reduced in elderly compared with younger adults. Case series comparing outcomes in young and elderly cohorts. Saint Louis University Division of Geriatric Medicine. Healthy adult outpatients and staff members aged < 50 (young) or > or = 65 (elderly) years. Peripheral blood mononuclear cells were assayed for CTL activity by a 51chromium release assay following 1 week of in vitro stimulation with influenza A/PR/8/34 (H1N1) virus. Percent specific lysis of autologous and allogeneic influenza virus-infected target cells. Specific lysis of autologous A/PR-infected targets was significantly lower in elderly compared to young subjects (P < 0.01), and exceeded 10% in a significantly lower proportion of elderly compared with younger subjects (P < 0.05), but was not influenced by a history of vaccination within the preceding 12 months. Cytotoxic effectors were class I human leukocyte antigen (HLA)-restricted and displayed heterosubtypic cross-reactivity but were unable to lyse influenza B-infected targets. These results demonstrate an age-related decline of influenza A virus-specific CTL activity and suggest that CTL responses to inactivated virus vaccine are of short duration.