FCGR2B and hypersensitivity pneumonitis: This finding of an important contribution of FcγRIIB to disease onset and severity is in agreement with previous reports that have linked polymorphisms in FcγRIIB with autoimmune diseases including SLE (41, 42), rheumatoid arthritis (43), anti-GBM diseases (44), IC-mediated alveolitis (45), and collagen-induced arthritis (46).