T helper cell

T helper (Th) cells play an important role in the adaptive immune system.

Th1
Th1 cells are involved in cell-mediated immunity against viruses and intracellular bacteria. They are triggered by IL-12, IL-2 and their effector cytokine is IFN-γ. he main effector cells of Th1 immunity are macrophages as well as CD8 T cells, IgG B cells, and IFN-γ CD4 T cells.

Autoimmune diseases characterized by a Th1 immune profile include rheumatoid arthritis, multiple sclerosis, Type 1 diabetes, Sjorgen's Syndrome and Chron's Disease.

Th2
Th1 cells are involved in humoral immunity against extracellular parasites, bacteria, toxins and allergens. They are triggered by IL-4 and their effector cytokines are IL-4, IL-5, IL-9, IL-10 and IL-13. The main effector cells are eosinophils, basophils, and mast cells as well as B cells, and IL-4/IL-5 CD4 T cells.

Autoimmune diseases characterized by a Th1 immune profile include Lupus, Scleroderma, Inflammatory Bowel Disease, and Asthma. Chronic fatigue syndrome is characterized by a Th2 cytokine profile.