OBJECTIVETo investigate whether Mycobacterium tuberculosis heat shock protein 70 (TB.HSP70) can be used as an adjuvant carrier to stimulate immune response to an accompanying cytotoxic T lymphocytes (CTL) epitope peptide from hepatitis B virus (HBV) core antigen.

METHODSIn vitro, peripheral blood mononuclear cells (PBMCs) from chronic hepatitis B volunteers were stimulated with TB.HSP70-CTL fusion protein and TB.HSP70/CTL complex, and then HBV specific CTL activity was assessed. In vivo, the CD4+ T, CD8+ T and natural killer cells (NKs) in the peripheral blood and in spleens of the immunized mice were measured by flow cytometry and the protective HBV specific immune responses of the mice were also evaluated.

RESULTSThe results revealed that both of them could induce HBV specific CTL response in human PBMCs and in the immunized mice. In the mice they activated CD4+ T, CD8+ T and NKs. Furthermore, the immunocompetence of the TB.HSP70-CTL fusion protein was stronger than that of TB.HSP70/CTL complex. The HBV specific killing rate was 28.9%, the CD8+ T cell population was 43.9% and the NKs was 13.6% in splenocytes of immunized mice with TB.HSP70-CTL fusion protein. The CTL peptide alone was capable of generating weak CTL lysis. The TB.HSP70 showed almost no target cell killing.

CONCLUSIONThe results demonstrate that TB.HSP70 may be used as a new adjuvant carrier to improve the immunogenicity of short CTL epitope and produce effective CTL response.