FOXP3 and autoimmune disease: We have shown that systemic delivery of autoimmune disease-relevant peptide-major histocompatibility complex class II (pMHCII)-coated nanoparticles (pMHCII-NP) triggers the formation of large pools of disease-suppressing Foxp3– TR1 cells from cognate T-follicular helper (TFH) cell precursors.