 | Figure 2
Nature Medicine
11, S63 - S68 (2005)
Published online: ; | doi:10.1038/nm1210
Targeting the innate immune response with improved vaccine adjuvantsAchal Pashine, Nicholas M Valiante
& Jeffrey B Ulmer | | | | Figure 2. Initiation of the immune response.
Upon interaction with PAMPs (1), resting innate immune cells and certain nonimmune cells, such as tissue epithelial cells, secrete cytokines and chemokines. Double arrows indicate cross-talk between cells. Key features of this early activation are an increase in APC function characterized by increased costimulatory capacity and upregulation of surface major histocompatibility complex molecules (2). Cells of the adaptive immune system, such as CD4+ and CD8+ T cells, then recognize presented antigen and undergo clonal expansion (3). Cognate interaction between T and B cells leads to B cell activation, expansion and conversion to plasma cells that secrete specific antibodies (4). Activated dendritic cells can also act directly on CD8+ T cells to license them to become effector CTLs (5) and may also secrete soluble factors that block the immunosuppressive effects of CD25+ Treg (6). A proportion of adaptive immune cells also differentiate into memory cells that will be ready for a secondary encounter with the specific pathogen. Thus, complete elimination of pathogens is achieved by effector cells and soluble factors of both the innate and adaptive immune systems.
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