To our knowledge, this is the first report of PRCA as a result of IL-2 therapy, despite clear documentation of other autoimmune phenomena occurring subsequent to IL-2 therapy, including hypothyroidism, reactivation of inflammatory bowel disease, psoriasis,14, , , , -19 and activation of occult rheumatoid arthritis (J. P. Dutcher, personal communication). This evidence concerns the gene IL2 and inflammatory bowel disease.