Attenuated Listeria monocytogenes carrier strains can deliver an HIV-1 gp120 T helper epitope to MHC class II-restricted human CD4+ T cells

Carlos A. Guzmán, Daniele Saverino, Eva Medina, Daniela Fenoglio, Birgit Gerstel, Andrea Merlo, Giuseppina Li Pira, Francesca Buffa, Trinad Chakraborty, Fabrizio Manca

Research output: Contribution to journalArticlepeer-review


Listeria monocytogenes is a facultative intracellular pathogen which, following uptake by macrophages, escapes from the phagosome and replicates in the cytoplasm. This property has been exploited using recombinant L. monocytogenes as a carrier for the intracytoplasmic expression of antigens when MHC class I-restricted cytotoxic T lymphocyte responses are required. Much less is known of the ability of these bacteria to trigger MHC class II-restricted responses. Here, we demonstrate that after ingestion of L. monocytogenes expressing a T helper epitope from the gp120 envelope glycoprotein of HIV, human adherent macrophages and dendritic cells can process and present the epitope to a specific CD4+ T cell line in the context of MHC class II molecules. No significant differences were observed when the attenuated strains were trapped in the phagolysosome or impaired in the capacity to spread intracellularly or from cell to cell. Similar results were obtained using carrier proteins that were either secreted, associated with the bacterial surface, or restricted to the bacterial cytoplasm. A dominant expression of the TCR Vβ 22 gene subfamily was observed in specific T cell lines generated after stimulation with the recombinant strains or with soluble gp120. Our data show that in this in vitro system L. monocytogenes can efficiently deliver antigens to the MHC class II pathway, in addition to the well-established MHC class I pathway. The eukaryotic cell compartment in which the antigen is synthesized, and the mode of display seem to play a minor role in the overall efficiency of epitope processing and presentation.

Original languageEnglish
Pages (from-to)1807-1814
Number of pages8
JournalEuropean Journal of Immunology
Issue number6
Publication statusPublished - Jun 1998


  • Antigen presentation
  • gp120
  • HIV
  • Human T cell
  • Listeria monocytogenes

ASJC Scopus subject areas

  • Immunology


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