TNF and rheumatoid arthritis: Based on these observations and the open questions about the role of peri-PLV mast cells on lymphatic function and association with RA pathogenesis, we hypothesized that: i) peri-PLV cells are indeed pro-inflammatory mast cells that regulate lymphatic function by releasing (degranulating) catabolic factors, and ii) genetic ablation and pharmacological inhibition of mast cells ameliorates lymphatic dysfunction and reduces inflammatory-erosive arthritis in TNF-tg mice.