Figure 1.

A schematic of the proposed mechanism of adjuvanticity of membrane bound and secreted HSP70. Tissue surveillance by immature DCs (iDCs) may result in recognition and binding to (1) secreted HSP70 or (2) membrane-bound HSP70, which represent danger signals (DAMPs), and thus the DCs are attracted to the antigen-positive cells. HSP70/TLR ligation results in DC maturation and co-stimulatory molecule upregulation and cytokine secretion. In turn, the mature DC expressing these co-stimulatory molecules process and present antigen in a MHC-restricted manner, migrate to the lymph nodes and interact with naive T cells to generate antigen-specific T cells.