TLR8 and rheumatoid arthritis: To assess the capability of TLRs to induce IL-1β from RA monocytes, peripheral blood CD14+ monocytes from RA patients and HCs were stimulated with Pam3CSK4 to activate the TLR1/2 heterodimer, LPS to stimulate TLR4 and R-848, a ligand that can activate both TLR7 and TLR8 (Fig. 1).