FCGR2B and arthritic joint disease: We found that Fcgr2b−/− x Cd55host+/+BM−/− and Fcgr2b−/− x Cd55host−/−BM+/+ mice were equally susceptible to K/BxN serum transfer arthritis compared to Fcgr2b−/− x Cd55host+/+BM+/+ mice (Figure 5E) with a tendency toward slightly higher disease scores and granulocyte infiltration in synovial tissue (Figure 5E/F).