Interleukin 1, Interleukin 10 and tumour necrosis factor alpha are produced by activated macrophages. Interleukin 12 is produced by activated macrophages and dendritic cells. Type I interferons (IFN-alpha and IFN-beta) are produced by many cell types and inhibit viral replication in cells. Interleukin 2 is produced by T-helper (Th) cells. Interleukin 4 is produced by macrophages and Th2 cells. Interleukin 5 is produced by Th2 cells. Transforming growth factor beta is produced by T cells and many other cell types and is primarily an inhibitory cytokine, controlling the proliferation of T cells and the activation of macrophages.