Although the blood concentration of IL-2 was also found to be very low (approximately 1 pg/mL) in several other studies of non-rheumatic diseases36–38 and mostly below the lower limit of detection in a very recent study of predicting drug-free RA remission by a composite score incorporating three transcripts, IL-27, and Boolean remission39, and thus only detectable using high-sensitivity measurements, IL-2 is crucial for the development and expansion of regulatory T cells40,41 which may be associated with sustained RA remission. This evidence concerns the gene IL2 and rheumatoid arthritis.