Abstracts

Innate immune recognition of the immunotherapeutic fusion protein HspE7.

Poster & Abstract presented at Keystone Symposia: Interfaces between Innate and Adaptive Immunity - Keystone, CO January 22-27, 2001

Chu N.R.(1), Bantroch S.(1), Wiebe E.(1), Cho B.K.(2), Palliser, D.(2), Boux L.(3), Siegel, M.I.(3), Mizzen L.(1)

1) StressGen Biotechnologies, Victoria, BC, Canada.
2) Center for Cancer Research, MIT, Cambridge, MA, USA.
3) StressGen Biotechnologies, Collegeville, PA, USA.

We have shown previously that administration of HspE7 (a recombinant fusion protein comprised of Mycobacterium bovis BCG Heat shock protein (Hsp) 65 covalently linked to human papilloma virus (HPV)16 E7, designated SGN-00101) induces, without added adjuvants, cellular immunity and tumor rejection in the murine TC-1 cervical cancer model.

Recent work suggests that Hsp bind receptors present on antigen presenting cells. To characterize the innate immune mechanisms associated with the immunogenicity of HspE7, experiments were performed using short-term splenocyte cultures from naïve mice. The results show that HspE7 elicits the secretion of IFN-g from splenocytes of C57BL/6, C3H or Balb/c mice. To examine whether Tlr4 plays a role in this response, splenocytes from the following mouse strains were stimulated by HspE7: C3H/HeN (LPS responsive, Tlr4 wild type), C3H/HeJ (LPS hyporesponsive, Tlr4-mutant), C57BL/10 ScSn (LPS responsive, Tlr4 wild type) and C57BL/10 ScnCr (LPS resistant, Tlr4 null). IFN-g secretion is observed in all cases, albeit at lower magnitudes in Tlr4 deficient mice. In addition, HspE7 stimulation of bone marrow-derived dendritic cells from C57BL/6 (wt) or C3H/HeJ mice upregulates MHC I molecules. Therefore, the data suggests that HspE7 activates the innate immune system via dendritic cells, resulting in the secretion of cytokines such as IFN-g.