HUMAN GAMMA DELTA T-CELL RESPONSE TO LISTERIA-MONOCYTOGENES PROTEIN-COMPONENTS IN-VITRO/

Listeria monocytogenes is a facultative intracellular pathogen that re plicates inside mononuclear phagocytes and induces specific cellular i mmunity. Listeriosis encompasses many clinical syndromes and meningiti s is the most frequent clinical manifestation. Human alpha/beta and ga mma/delta T cells have been shown to respond to L. monocytogenes antig ens and to play an important role in resistance against listerial infe ction. We investigated the nature of listerial ligands and the influen ce of the major virulence factor, listeriolysin (hly), on the stimulat ion of human gamma/delta T cells from healthy individuals. We found th at a listerial somatic protein ligand, which is sensitive to proteinas e treatment, stimulated gamma/delta T cells in vitro; the majority of Listeria-responsive gamma/delta T cells expressed V gamma 9V delta 2 T -cell receptor chains and human leucocyte antigen-DR molecules; gamma/ delta T-cell responses to hly(+) and hly(-) Listeria strains were comp arable; L. monocytogenes strains of different virulence stimulated gam ma/delta T cells equally. Thus, protein components of L. monocytogenes unrelated to virulence activate human gamma/delta T cells in vitro.