Title

Analysis of immunogenicity of heat shock protein 70-peptide complexes

Date of Completion

January 2001

Keywords

Health Sciences, Immunology

Degree

Ph.D.

Abstract

Heat shock protein 70 (hsp70) is a family of highly conserved and abundant proteins with relative molecular mass around 70,000 Daltons. The hsp70 molecules consist of a N-terminal ATPase domain and a C-terminal peptide-binding domain. It has been shown that nucleotide ATP binding of hsp70 triggers a conformational change in the protein, which results in release of the bound peptide. All conventional methods to purify hsp70 involve utilize ATP-affinity chromatography, or other methods which unavoidably dissociate peptide from hsp70. Here I have developed a new method by replacing the ATP-affinity chromatography with ADP-affinity chromatography, which enables one to purify hsp70 with its associated peptide. ^ It is known that heat shock protein-peptide complexes isolated from tumors, are capable of eliciting potent cellular immunity against the tumors. The efficacy of using ADP-affinity chromatography purified hsp70-peptide complexes as cancer vaccines was tested in a number of marine tumor models. I demonstrated that tumor derived hsp70-peptide complexes elicit strong antitumor immunity both prophylactically and therapeutically. This anti-tumor immunity induced by hsp70-peptide complexes is specific to each tumor individually. In addition, the anti-tumor immunity is dependent exclusively on the peptide that is associated with hsp70. ^ To explore the cellular mechanisms for the anti-tumor immunity elicited by hsp70-peptide complexes, tumor rejection assay was employed. I depleted CD4+, or CD8+ T cells or functionally inactivated phagocytic antigen presenting cells in mice prior to, or after the immunization with hsp70-peptide complexes. Results revealed that all three cell types are crucial for the anti-tumor immunity elicited by hsp70-peptide complexes. Additional studies of adoptively transferring the anti-tumor immunity induced by hsp70-peptide complexes confirmed the results. ^ Taken together, the work presented in this thesis indicates that, hsp70-peptide complexes are attractive candidates for vaccines against cancer and infectious diseases. In addition, these finding strongly suggests that hsp70-peptide complexes may interact with antigen presenting cells, which subsequently prime CD4+ and CD8+ T cells in vivo. ^