Listeriolysin O-liposome-mediated cytosolic delivery of macromolecule antigen in vivo: enhancement of antigen-specific cytotoxic T lymphocyte frequency, activity, and tumor protection

Biochim Biophys Acta. 2002 Jun 13;1563(1-2):7-17. doi: 10.1016/s0005-2736(02)00368-1.


Cytotoxic T lymphocytes (CTLs) are primed by peptide antigens that are endogenously processed in the cytosol and presented in the context of major histocompatibility complex I (MHC I) molecules of antigen-presenting cells (APCs). Exogenous soluble protein antigens do not gain efficient entry into the cytosol of APCs, and therefore requires a special cytosolic delivery method. We have developed such a delivery strategy adopting the well-elucidated cytosol-invading listerial endosomal escape mechanism, and report here an efficient delivery of exogenous whole protein antigen into the cytosol in a mouse model. Co-encapsulation of listeriolysin O (LLO) inside liposome (LLO-liposome) was required for delivery of ovalbumin (OVA) into the cytosol of APCs in primary cultures. LLO-liposome-mediated OVA immunization in mice engendered significantly higher OVA-specific CTL activity and increased antigenic peptide-specific CTL precursor (CTLp) frequency as compared to non-LLO-liposome or soluble OVA immunizations. Interferon-gamma (IFN-gamma) production upon specific stimulation by MHC I-restricted peptide was also significantly stronger by the inclusion of LLO in the liposomes. Rerouting of antigen into the cytosol by LLO-liposomes, however, did not reduce the extent of anti-OVA antibody responses. Moreover, LLO-liposome-antigen vaccination was robust in conferring protection to mice from lethal challenges with antigen-expressing tumor cells. Our study demonstrates a novel delivery system for efficient introduction of exogenous protein into the cytosol in vivo, priming cellular immune responses, which are protective in nature.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Antigen-Presenting Cells / immunology
  • Bacterial Toxins*
  • Cancer Vaccines / administration & dosage
  • Cells, Cultured
  • Cytosol / immunology
  • Drug Delivery Systems
  • Egg Proteins / administration & dosage
  • Egg Proteins / immunology
  • Egg Proteins / pharmacology
  • Heat-Shock Proteins / administration & dosage*
  • Hemolysin Proteins
  • Immunization
  • Interferon-gamma / metabolism
  • Interleukin-2 / metabolism
  • Liposomes
  • Macrophages / immunology
  • Mice
  • Mice, Inbred C57BL
  • Models, Animal
  • Ovalbumin / administration & dosage
  • Ovalbumin / immunology
  • Ovalbumin / pharmacology
  • Peptide Fragments
  • Recombinant Proteins / administration & dosage
  • T-Lymphocytes, Cytotoxic / immunology*
  • T-Lymphocytes, Cytotoxic / metabolism


  • Bacterial Toxins
  • Cancer Vaccines
  • Egg Proteins
  • Heat-Shock Proteins
  • Hemolysin Proteins
  • Interleukin-2
  • Liposomes
  • OVA-8
  • Peptide Fragments
  • Recombinant Proteins
  • Interferon-gamma
  • Ovalbumin
  • hlyA protein, Listeria monocytogenes