Figure 2. General mechanism of induction of antigen-specific CD8⁺ T-cell immunity by biodegradable particles co-encapsulating Ag and adjuvant. Particles co-encapsulating Ag and an adjuvant (A) are phagocytosed by dendritic cells (DCs). DCs undergo maturation (B), upregulating costimulatory molecules (C) and simultaneously cross-presenting Ag in context of MHC class I (i.e., presentation to CD8⁺ T cells) (D). In the draining lymph node CD8⁺ T cells become activated (i.e., cytotoxic T cells) and concomitantly activated CD4⁺ T cells secrete cytokine help (E) to activated CD8⁺ T cells. Cytotoxic T cells travel via peripheral blood to tumor sites and eradicate Ag expressing cancerous cells or those infected with intracellular pathogens (F). Suppressor cells such as Tregs secrete inhibitory cytokines that prevent T-cell effector activation/function (G) leading to dampening of immune response.