TNFSF13B and rheumatoid arthritis: We further observed a population of fibroblasts in psoriasis that express CCL19, TNFSF13B (BAFF), and CXCL12. Notably, expression of CCL19 and BAFF by synovial fibroblasts has been implicated in the progression of rheumatoid arthritis (Pickens et al., 2011; Reyes et al., 2008), but their relevance to psoriasis has yet to be described and will require further exploration.