CD40LG and rheumatoid arthritis: RF are autoantibodies directed against the Fc-tail of immunoglobulin G. To study the IgG binding to IgM-RF+ pEVs, we coupled pEVs isolated from 8 RF+RA patients to anti-CD63 beads, incubated them with Phycoerythrin (PE)-conjugated IgG and analyzed IgG binding using FC.