Impaired production of TNF-α by dendritic cells of older adults leads to a lower CD8+ T cell response against influenza

► We investigate DCs of healthy older (≥65 years) and young adults (20-40 years). ► DCs of older adults show an impaired activation of influenza-specific CD8+ T cells. ► Mature DCs of older adults express less TNF-α, HLA class I and maturation markers. ► Supplementing TNF-α restores DC function of older adults. ► TNF-α is a major factor in the DC-mediated CD8+ T cell response against influenza.