is il 2 a cytokine?
IL-2 is a small 15.5-kDa four α-helical bundle cytokine, which has been one of the most studied cytokines since its discovery about 38 y ago. It is produced predominately by antigen-simulated CD4+ T cells, while it can also be produced by CD8+ cells, natural killer (NK) cells, and activated dendritic cells (DC).