Toll-like receptors (TLRs) are crucial for the innate immune response to pathogens. In humans, ten TLRs (TLR1–TLR10) have been identified, with TLR2, TLR4, and TLR5 recognizing peptidoglycan, lipopolysaccharide, and flagellin, respectively. TLR7 and TLR8 are known to recognize synthetic compounds, with R-848 being a known TLR7 ligand. Studies show that R-848 activates immune cells via the TLR7 MyD88-dependent signaling pathway. Hemmi et al. demonstrated that R-848 activates NF-κB and proinflammatory cytokines in wild-type mice, but not in MyD88- or TLR7-deficient mice. Human TLR7 was shown to confer responsiveness to R-848 in HEK293 cells. Additionally, R-848 activates NF-κB via TLR8 or TLR7. HEK293 cells transfected with human TLR8 or TLR7 showed NF-κB activation upon R-848 stimulation. TLR7 showed higher sensitivity to R-848, but TLR8 was more effective at inducing NF-κB at higher concentrations. In contrast, murine TLR8 did not activate NF-κB upon R-848 stimulation, suggesting that TLR8 is nonfunctional in mice. These findings indicate that both human TLR7 and TLR8 can independently recognize R-848, suggesting possible redundancy among these receptors. The differential dose response may allow fine-tuning of the immune response to varying concentrations of R-848 and other ligands. Further studies are needed to identify the natural ligands for these receptors and clarify the status and function of murine TLR8.Toll-like receptors (TLRs) are crucial for the innate immune response to pathogens. In humans, ten TLRs (TLR1–TLR10) have been identified, with TLR2, TLR4, and TLR5 recognizing peptidoglycan, lipopolysaccharide, and flagellin, respectively. TLR7 and TLR8 are known to recognize synthetic compounds, with R-848 being a known TLR7 ligand. Studies show that R-848 activates immune cells via the TLR7 MyD88-dependent signaling pathway. Hemmi et al. demonstrated that R-848 activates NF-κB and proinflammatory cytokines in wild-type mice, but not in MyD88- or TLR7-deficient mice. Human TLR7 was shown to confer responsiveness to R-848 in HEK293 cells. Additionally, R-848 activates NF-κB via TLR8 or TLR7. HEK293 cells transfected with human TLR8 or TLR7 showed NF-κB activation upon R-848 stimulation. TLR7 showed higher sensitivity to R-848, but TLR8 was more effective at inducing NF-κB at higher concentrations. In contrast, murine TLR8 did not activate NF-κB upon R-848 stimulation, suggesting that TLR8 is nonfunctional in mice. These findings indicate that both human TLR7 and TLR8 can independently recognize R-848, suggesting possible redundancy among these receptors. The differential dose response may allow fine-tuning of the immune response to varying concentrations of R-848 and other ligands. Further studies are needed to identify the natural ligands for these receptors and clarify the status and function of murine TLR8.