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 cytokines, including IL-4, IL-5, and IL-13, which promote immune responses. Th2 cells are particularly important in the context of allergic reactions and asthma. When the immune system mistakenly identifies harmless substances, like pollen or pet dander, as threats, Th2 cells can trigger an exaggerated immune response. This can lead to inflammation and symptoms associated with allergies, highlighting the dual role of Th2 cells in both protecting against infections and contributing to allergic diseases.