Heat shock fusion proteins as vehicles for antigen delivery into the major histocompatibility complex class I presentation pathway

Abstract

Mice immunized with heat shock proteins (hsps) isolated from mouse tumor cells (donor cells) produce CD8 cytotoxic T lymphocytes (CTL) that recognize donor cell peptides in association with the major histocompatibility complex (MHC) class I proteins of the responding mouse. The CTL are induced apparently because peptides noncovalently associated with the isolated hsp molecules can enter the MHC class I antigen processing pathway of professional antigenpresenting cells. Using a recombinant heat shock fusion protein with a large fragment of ovalbumin covalently linked to mycobacterial hsp70, we show here that when the soluble fusion protein was injected without adjuvant into H-2 b mice, CTL were produced that recognized an ovalbumin-derived peptide, SIINFEKL, in association with K b . The peptide is known to arise from natural processing of ovalbumin in H-2 b mouse cells, and CTL from the ovalbumin-hsp70-immunized mice and a highly effective CTL clone (4G3) raised against ovalbumin-expressing EL4 tumor cells (EG7-OVA) were equally effective in terms of the concentration of SIINFEKL required for half-maximal lysis in a CTL assay. The mice were also protected against lethal challenge with ovalbuminexpressing melanoma tumor cells. Because large protein fragments or whole proteins serving as fusion partners can be cleaved into short peptides in the MHC class I processing pathway, hsp fusion proteins of the type described here are promising candidates for vaccines aimed at eliciting CD8 CTL in populations of MHC-disparate individuals.

Secretory heat-shock protein as a dendritic cell-targeting molecule: a new strategy to enhance the potency of genetic vaccines

“…These findings are consistent with data in earlier reports of recombinant HSP70 fusion proteins that included HIV-1 p24, 36 OVA, 37,39 influenza virus NP, 45 or HPV16 E7 38 as model antigens or E7/HSP70 fusion proteins released from dying cells. 46,47 However, it remains a mystery why the HSP-mediated presentation of E7 antigens did not induce CD4 þ T-helper responses, presumably through the receptor-mediated class II antigen presentation pathway.…”

“…Peptides complexed to HSPs in vitro, [26][27][28] as well as HSP-peptide complexes purified from cells expressing viral proteins 29,30 or tumor cells, [31][32][33][34][35] induce specific CTL responses. Finally, recombinant HSP-antigen fusion proteins 36,37 were able to elicit CD4 þ -independent CD8 þ cytotoxic T-lymphocyte (CTL) responses. [38][39][40] In the present study, we sought to enhance the potency of DNA vaccines by using HSP70 as a DC-targeting molecule to enhance antigen cross-presentation and DC maturation.…”

Immunotherapy of Epstein-Barr Virus Associated Malignancies Using Mycobacterial HSP70 and LMP2A356–364 Epitope Fusion Protein

“…However, among EBV latent-cycle proteins, CD4 + T responses to LMP2A epitopes are much less frequent than EBNA1 and LMP1 (18). Previous studies have demonstrated that MtHsp70 accompanied antigens can induce potential antigen-specific CD8 + T cells with cytolytic and cytokine-secreting functions through CD4 + T cell independent modes (21,23,(39)(40)(41)(42). In this study, we conjugated a conserved LMP2A HLA-A2.1 restricted epitope LMP2A 356-364 to MtHsp70, which not only induces LMP2A 356-364 specific immune recognition in vitro, but also elicits LMP2A specific CTL in vivo.…”

“…Previous studies indicate that MtHsp70 can be used as an adjuvant-free carrier to stimulate the humoral and cellular immune response to accompanied proteins or synthetic peptides (20,21). Many studies have demonstrated that MtHsp70 accompanied antigens are able to induce potential antigen-specific CD8 + T cells with cytolytic and cytokine-secreting functions through CD4 + T cell independent mode (22,23).…”

A transcriptional feedback loop for tissue-specific expression of highly cytotoxic genes which incorporates an immunostimulatory component

“…Moreover, such a strategy would have the additional therapeutic advantage that it should lead to tumour cell-specific expression of inducible hsps, such as hsp70, which we 13,14 and others [18][19][20][21] have previously shown to have very potent immunostimulatory properties in anti-tumour vaccination settings.…”