Antigen‐specific T cell receptor antagonism by antigen‐presenting cells treated with the hemolysin of Listeria monocytogenes: a novel type of immune escape
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Media type:
E-Article
Title:
Antigen‐specific T cell receptor antagonism by antigen‐presenting cells treated with the hemolysin of Listeria monocytogenes: a novel type of immune escape
Description:
<jats:title>Abstract</jats:title><jats:p>We have examined the influence of listeriolysin O (LLO), the hemolysin secreted by the pathogenic bacterium <jats:italic>Listeria monocytogenes</jats:italic>, 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.</jats:p>