Abatacept in IgG4-RD. Plausible, but does it work? Pilot n=10 @MGHrheumatology ABA +<4w PNL Some hit, some miss - but mechanistic correlates of response: Tfh2, unswitched memory B cells. Exploring new options (w real benefit) very welcome in IgG4-RD! #ACR20 ABST1480 @RheumNow https://t.co/0saS941Lga