A method to treat an autoimmune disease is provided. The method involves administration of interleukin-15 receptor (IL-15R) agonists in an amount effective to ameliorate a symptom of the autoimmune disease. The invention also involves a method to treat an autoimmune disease by ex-vivo expansion of CD44+CD122+Kir+ CD8+ Treg cells and administration of the CD44+CD122+Kir+ CD8+ Treg cells. Compositions comprising CD44+CD122+Kir+ CD8+ Treg cells are also provided. Methods for stimulating an immune response to an antigen are also provided.
