IL7 and rheumatoid arthritis: Circulating levels of IL-7 have been extensively studied in HC and active RA [10,15,17] Median IL-7 levels were 14.2 pg/ml in HC (Figure 1A, n = 80, range 7.9 to 30.8 pg/ml with a 95% of values above 10 pg/ml, in agreement with Goëb et al. [17] and a review of 17 manuscripts incorporating approximately 400 healthy donors [15]) and 7.6 pg/ml in active RA (with >2 years duration, range 1.9 to 10.9 pg/ml) on several DMARD treatment regimes.