Immune system versus tumor: shifting the balance in favor of DCs and effective immunity
J. Clin. Invest. Howard L. Kaufman, et al. 113:664 doi:10.1172/JCI21148 [
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Figure 2DCs exist primarily in two distinct phenotypic forms. Immature DCs are able to circulate through peripheral tissues and sample soluble antigen and possibly necrotic or apoptotic cells. These DCs express few costimulatory molecules and are unable to prime T cell responses. Once DCs begin to process and present antigen they “mature” into a more stellate shape capable of presenting antigen and initiating an adaptive immune response. The presence of TLRs allows the DC to recognize common molecular patterns found on a variety of pathogenic organisms, so-called pathogen-associated molecular patterns. TLR signaling is thought to represent a major mechanism of innate immunity and is another process that results in APC conditioning and release of proinflammatory cytokines. Maturation of DCs also results in increased expression of MHC, costimulatory molecules, and chemokine receptors that direct DCs to regional lymph nodes where they are more likely to encounter their cognate T cell and are able to prime T cell responses.
