TLR7 and rheumatoid arthritis: To study whether bifunctional NPs indeed target B cells that specifically recognize the β60-74Cit peptide, PBMCs from selected RA patients having high β60-74Cit peptide-specific serum antibody level and from healthy donors were stimulated with the TLR7/TLR8 agonist, R848, and IL-2 for 72 hours, and then the harvested cells were incubated with the bifunctional NPs, followed by the addition of pooled human sera or inactivated sera at different concentrations.