Stimulation of Th1-polarizing cytokines, C-C chemokines, maturation of dendritic cells, and adjuvant function by the peptide binding fragment of heat shock protein 70.

The peptide binding C-terminal portion of heat shock protein (HSP)70 (aa 359-610) stimulates human monocytes to produce IL-12, TNF-alpha, NO, and C-C chemokines. The N-terminal, ATPase portion (HSP70(1-358)) failed to stimulate any of these cytokines or chemokines. Both native and the truncated HSP70(359-610) stimulation of chemokine production is mediated by the CD40 costimulatory molecule. Maturation of dendritic cells was induced by stimulation with native HSP70, was not seen with the N-terminal HSP70(1-358), but was enhanced with HSP70(359-610), as demonstrated by up-regulation of CD83, CCR7, CD86, CD80, and HLA class II. In vivo studies in macaques showed that immunization with HSP70(359-610) enhances the production of IL-12 and RANTES. Immunization with peptide-bound HSP70(359-610) in mice induced higher serum IgG2a and IgG3 Abs than the native HSP70-bound peptide. This study suggests that the C-terminal, peptide-binding portion of HSP70 is responsible for stimulating Th1-polarizing cytokines, C-C chemokines, and an adjuvant function.