Toll and Toll-Like Receptors: An Immunologic Perspective

Abstract

The host defense system of higher animals comprises both innate and adaptive immunity. Dendritic cells (DCs), professional antigen presenting cells, play critical roles in linking these two types of immunity in response to microbial stimuli. DCs express a group of type I transmembrane proteins, Toll-like receptors (TLRs), which can recognize a number of microorganism-derived molecular structures, including membrane components and nucleic acids. This recognition is a prerequisite for DC activation and maturation. Each TLR family member can provoke overlapping, but distinct biological consequences. In this chapter, we discuss how TLRs, as adjuvant receptors, instruct DCs to drive host defense.