Objective: To investigate whether influenza A-specific cytotoxic T lymphocyte (CTL) activity is reduced in elderly compared with younger adults.
Design: Case series comparing outcomes in young and elderly cohorts.
Setting: Saint Louis University Division of Geriatric Medicine.
Participants: Healthy adult outpatients and staff members aged < 50 (young) or > or = 65 (elderly) years.
Methods: 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.
Measurements: Percent specific lysis of autologous and allogeneic influenza virus-infected target cells.
Main results: 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.
Conclusions: 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.