IL5 and arthritic joint disease: They termed this subset of synovial cells “regulatory eosinophils” and found that it expanded in response to IL-5, akin to the IL-5 dependent, recruitable “iEos” identified in the lung by Mesnil et al. Furthermore, IL-5 blockade, in this model, blocked asthma-induced resolution of arthritis and led to the attenuation of eosinophil accumulation in the lung (iEos).