The invention hereby offered for licensing is in the field of Immunotherapy and more specifically in therapy of autoimmune diseases such as Type I diabetes, multiple sclerosis, rheumatoid arthritis and systemic lupus erythematosis and immune mediated allergies such as asthma as well as in transplantation-related disorders, such as graft acceptance and graft-versus-host-disease (GVHD).

While the role of FOXP3⁺ regulatory T cells (Tregs) in the maintenance of self-tolerance and immune homeostasis has been established and thus their use in adoptive immunotherapy has been contemplated, there is still no good way to purify and expand these cells in an efficient and reproducible manner ex vivo for use in human therapy. The subject invention provides a method that allows such purification for use in expansion cultures to generate sufficient numbers of cells and purity for cell-base immunotherapy. The method is based on the finding that Tregs selectively express Latency Associated Peptide (LAP) and CD121b (IL-1 Receptor Type 2) and on the ability to selectively separate these cells from other immune cells that are potentially hazardous, through the use of magnetic particles which specifically bind to either one of these two surface molecules and selectively separate those cells from the non-Tregs.