Dendritic cells

Dendritic cells (DCs) are antigen-presenting cells, made in your bone marrow, that bridge innate and adaptive immunity. Two main types circulate in your blood. Plasmacytoid DCs (pDCs) detect viral nucleic acids through TLR7 and TLR9, and release type I interferons (IFN-α/β). Conventional myeloid DCs (cDCs) capture antigens, chop them into peptides, and present them on MHC class I and II, to prime CD8+ killer and CD4+ helper T cells. With age, pDC numbers fall. Jing et al. (2009) found fewer circulating pDCs in healthy elderly donors, with less IFN-α after flu stimulation. cDC numbers stay stable, but they take up antigen worse and show lower co-stimulatory markers (CD40, CD86). Aged DCs also have defective IRF-7 activation and reduced PI3-kinase activity. And in airway tissue, they show high prostaglandin D2, which blunts their migration to draining lymph nodes during viral infection, weakening T-cell priming (Wong & Goldstein, 2013). Aged DCs secrete less IL-10, release more pro-inflammatory cytokines, and lose the ability to make regulatory T cells. That drives a loss of peripheral tolerance and feeds inflammaging (Agrawal et al., 2017). The net result is weaker vaccine responses. Adjuvant approaches like MF59 are being studied, but they remain context-specific.

Last reviewed: June 22, 2026

This definition is educational and is not medical advice, a diagnosis, or treatment. Talk to a doctor about any health decisions. Read our full medical disclaimer