Memory T cells can be activated during a secondary infection through a couple of key mechanisms.
During a secondary infection, memory T cells in peripheral tissues can be activated through these pathways:
- Direct activation by pro-inflammatory cytokines: Memory T cells can be directly triggered by pro-inflammatory cytokines to perform their effector functions.
- Interaction with antigen-bearing dendritic cells: Memory T cells can interact with dendritic cells that are carrying antigens. This interaction generates a localized secondary effector T-cell response, which happens outside of the draining lymphoid tissue. This is mentioned in the provided reference.
In summary, memory T cell activation is triggered either directly by inflammatory signals or through antigen presentation by dendritic cells.
