TNF and rheumatoid arthritis: In active RA with myeloid and lymphoid synovitis, the synovial membrane is leucocyte-rich, including an increased number of proinflammatory macrophages that likely differentiate locally from blood monocytes attracted to synovial tissue and fluid by local chemokines,22 and these macrophages are the main producers of pathogenic TNF.4 11 17 In remission, most of the synovial inflammation resolves, but STMs in the lining layer persist.11 It would be important to establish if these macrophages have the same phenotype as those in healthy synovium.