These include pro-inflammatory T helper cells, or Th1, that produce interferon - γ and interleukin - 2, or IL - 2; anti-inflammatory Th2 cells that produce IL - 4, IL - 5 and IL - 13; pro-inflammatory Th17 cells that secrete IL - 17; and
immunomodulatory regulatory T - cells, or Tregs, that globally suppress activation of immune responses.