Interleukin 7-induced lymphoid neogenesis in arthritis: recapitulation of a fetal developmental programme?

Chronic inflammatory diseases such as rheumatoid arthritis (RA) are associated with the de novo formation of organised lymphoid tissue in a subpopulation of patients. The aberrant expression of cytokines and chemokines by stromal cells plays an important role in recruitment and survival of effector cells of the immune system and the development of ectopic tertiary lymphoid organs (TLOs). TLOs may promote the persistence of inflammation and the recognition of self antigens. Recent studies in man and mice now indicate that interleukin 7 (IL-7) is implicated in the formation of TLOs and progression of chronic inflammation.