Fig. 1.

Human toll-like receptors 1–9, expressed on dendritic cells and other APC, mediate the detection of pathogen associated molecular patterns and the up-regulation of costimulatory molecules and cytokines in response to these pathogen-associated signals. The low-molecular-weight immunopotentiatory drugs imiquimod and resiquimod signal via TLR-7 (while resiquimod can also signal via human, but not murine, TLR-8 at higher drug concentrations).