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  • Title: Antigen-specific T cell receptor antagonism by antigen-presenting cells treated with the hemolysin of Listeria monocytogenes: a novel type of immune escape.
    Author: Darji A, Stockinger B, Wehland J, Chakraborty T, Weiss S.
    Journal: Eur J Immunol; 1997 Jul; 27(7):1696-703. PubMed ID: 9247580.
    Abstract:
    We have examined the influence of listeriolysin O (LLO), the hemolysin secreted by the pathogenic bacterium Listeria monocytogenes, on major histocompatibility complex class II-dependent T cell activation. Stimulation of T cells by native antigens but not by peptides is inhibited upon pretreatment of antigen-presenting cells (APC) with LLO. Experiments presented here reveal that this inhibition is not due to a lack in processing of antigen by APC but is the result of an irreversible inactivation of T cells that recognize antigen on LLO-treated APC. Incubation of mixtures of two different T cells where only one antigen was presented on LLO-treated APC suggested that T cell inactivation is antigen specific. The inactivation was dominant and could be observed even in the presence of amounts of synthetic peptides that normally lead to T cell responses. This condition is reminiscent of the T cell inhibition observed when antagonistic and stimulatory peptides are added to APC at the same time. Our results thus reveal a novel type of interference by pathogens with antigen presentation and T cell stimulation that could give the pathogen a decisive advantage in dissemination and disease.
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