Immune response modifier. Potent antitumor and antiviral compound. Stimulates antibody secretion and cytokine production. Used as adjuvant to increase the effectiveness of vaccines. Potent and selective synthetic ligand for Toll-like receptor 7 (TLR7) in mouse and for TLR7 and TLR8 in human. Activates immune cells via the TLR7/TLR8 MyD88-dependent signaling pathway and leads to the induction of NF-kappaB. NLRP3/NALP3 inflammasome activator, independent of TLRs and RIG-I. Upregulator of the opioid growth factor receptor. Used in the treatment of skin lesions such as herpes simplex virus.