Th2, or T-helper 2 cells, are a type of immune cell that play a crucial role in the body's defense against parasites and allergens. They are part of the adaptive immune system and help activate other immune cells by releasing specific cytokines. This response is essential for combating infections, particularly those caused by helminths and protozoa. Th2 cells are also involved in allergic reactions, as they can promote the production of immunoglobulin E (IgE) antibodies. When exposed to allergens, Th2 cells can trigger an immune response that leads to symptoms such as inflammation and tissue damage. Understanding Th2 cells is important for developing treatments for allergies and autoimmune diseases.