T-helper 2 (Th2) cells are a type of immune cell that play a crucial role in the body's defense against infections, particularly those caused by parasites and allergens. They are part of the adaptive immune system and help activate other immune cells, such as B cells, which produce antibodies. Th2 cells are characterized by their production of specific signaling molecules called cytokines, which promote the immune response. These cytokines, including IL-4, IL-5, and IL-13, help regulate the activity of various immune cells and enhance the body's ability to fight off infections. Th2 cells are particularly important in allergic reactions, as they can contribute to inflammation and symptoms associated with conditions like asthma and hay fever. Understanding Th2 cells is essential for developing treatments for these allergic diseases.