To assess the relevance of IL-2R regulation of CEACAM1 in vivo, we examined the expression of CEACAM1 upon low-dose IL-2 therapy in 27 patients with 8 autoimmune diseases, i.e., systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), psoriasis, Crohn’s disease (CD), sclerosing cholangitis (SC), ankylosing spondylitis, Sjögren’s syndrome, and systemic sclerosis (SSc) (32). Here, IL2 is linked to rheumatoid arthritis.