Figure1 Interleukin (IL)7 induces contact‐dependent tumour necrosis factor α (TNFα) production primarily by CD14 monocytes/macrophages co‐cultured with CD4 T cells. (A) CD4 (5×10⁵/ml) and CD14 (5×10⁵/ml) cells from patients with rheumatoid arthritis (RA) (n = 6) were exposed to IL7 (10 ng/ml) when cultured alone for 3 days or when co‐cultured in the absence or the presence of a transwell (TW) to prevent cell contact. IL7 did not significantly stimulate TNFα production by separated CD4 or CD14 cultures, but did significantly increase TNFα production in the IL7‐stimulated co‐culture. (B) Mean fluorescence intensity of TNFα produced by co‐cultured CD4 and CD14 cells in the presence of IL7 was measured by fluorescence‐activated cell sorting analysis. IL7‐induced TNFα was expressed as a percentage of co‐cultured cells in the absence of IL7. Data are means (SEM) of three patients with RA. *p<0.05.