Background: IL2 is a member of the interleukin cytokine subfamily which includes IL4, IL7, IL9, IL15, IL21, erythropoietin, and thrombopoietin. IL2 is a secreted cytokine produced by activated CD4+ and CD8+ T lymphocytes, that is important for the proliferation of T and B lymphocytes. The IL2 receptor is a heterotrimeric protein complex whose gamma chain is also shared by IL4 and IL7. [taken from NCBI Entrez Gene (Gene ID: 3558)].