Interestingly, using the same approach to assess macrophage populations also described in human RA and OA10,11 we found quiescent macrophages and interferon (IFN)-activated macrophages significantly increased in LA (Fig. 4c; p = 0.0332 and 1.14e−06, respectively), whereas phagocytic macrophages were associated with OA. This evidence concerns the gene IFNA1 and rheumatoid arthritis.