Abstract

Toxoplasma gondii and other apicomplexan parasites are widely distributed obligate intracellular protozoa. A critical host mediator produced in response to T. gondii infection is IL-12. This cytokine is synthesized by dendritic cells, macrophages and neutrophils and plays a pivotal role in the production of IFN-gamma, which in turn activates antimicrobial effector cells. In the past several years, many of the receptors and signaling pathways that link pathogen detection to induction of IL-12 have been identified and characterized. Among these receptors the Toll-like Receptor (TLR) family can recognize all classes of pathogens and induce different types of immune responses. In the following review, the evidence for specific TLR function in host resistance to T. gondii is summarized.