{"type":"root","children":[{"type":"paragraph","children":[{"type":"text","value":"CD25 is the alpha chain of the IL-2 receptor. It is a type I transmembrane protein present on activated T cells, activated B cells, some thymocytes, myeloid precursors, and oligodendrocytes that associates with CD122 to form a heterodimer that can act as a high-affinity receptor for IL-2. Studies have shown that a large proportion of resting memory T cells constitutively express CD25."}]},{"type":"paragraph","children":[{"type":"text","value":"CD25 is expressed in most B-cell neoplasms, some acute nonlymphocytic leukemias, neuroblastomas, and tumor infiltrating lymphocytes. Its soluble form, called sIL-2R may be elevated in these diseases and is occasionally used to track disease progression. CD25 is also utilized in cases of mastocytosis."}]}]}