CD8A and infection: In peripheral lymphoid tissues, antigen-specific naive CD8+ T cells are activated after encountering homologous antigens presented by dendritic cells (DCs) and are rapidly cloned to produce large numbers of antigen-specific effector CD8+ T cells that enter the circulation and migrate to infection or tumor, secrete proinflammatory cytokines [interferon-γ, tumor necrosis factor-α, cytotoxic effector molecules (perforin, granzyme, etc.