ACTION OF CYTOKINES IL-12 AND IL-4 ON T-H ELPER CELLS - CELLULAR-IMMUNITY OR HUMORAL IMMUNITY

Two subsets of T-helper cells: T-helpers are divided into two subpopul ations called Th1 and Th2 depending on the pattern of cytokines they p roduce. These mutually antagonist subpopulations exert different funct ions. Th1 cells control cellular immunity whereas Th2 cells control hu moral immunity. Lymphocyte differentiation: Several factors are involv ed, but the presence of certain cytokines in the environment where cel lular interactions driving specific lymphocyte sensitization occur, is the main factor determining differentiation into Th1 or Th2. Crucial role of IL-12 and IL-4: IL-12 can polarize lymphocytes towards a Th1 p henotype and IL-4 can direct T lymphocytes towards a Th2 pattern. Prac tical implications: The use of cytokines, or cytokine-inhibiting agent s, offers a new strategic approach for intentional modulation of the i mmune response.