T-cell anergy induced by antigen presenting cells treated with the hemolysin of Listeria monocytogenes.

Antigen presenting cells (APC) that are infected with listeriolysin (LLO) secreting Listeria lack the ability to stimulate MHC class II restricted T-cells by conventional antigens. Similarly, T-cell activation by native proteins but not by peptides was inhibited upon pretreatment of APC with purified listeriolysin. The inhibition is due to an irreversible inactivation of T-cells that recognize antigen on infected or LLO treated APC. Inhibition was found to dominate over stimulation by peptides. This condition is reminiscent of T-cells inactivation by antagonistic peptides and represents a novel type of immune escape.