<prompt> IL-2 is secreted byCD4 lymphocytesCD8 cellsMacrophagesNeutrophils  <response>: IL-2 is a typical four a helix cytokine and is produced primarily by activated CD4 T cells, although expression by naive CD8 T cells, dendritic cells, and thymic cells has also been repoed 8, 9, 10, 11. In T cells, IL-2 synthesis is tightly regulated at the mRNA level by signals from the TCR and CD28 12. 