TNFSF13B and rheumatoid arthritis: Other notable sources of BAFF and APRIL include epithelial cells in the tonsils [23] and salivary glands [24], osteoclasts [25,26], villous cytotrophoblasts and mesenchymal cells in the placenta [27], synoviocytes from rheumatoid arthritis (RA) patients [28], and breast adipocytes [29].