T helper cells are a type of white blood cell that play a crucial role in the immune system. They help activate and direct other immune cells, such as B cells and cytotoxic T cells, to respond effectively to infections. T helper cells recognize specific antigens presented by antigen-presenting cells and release signaling molecules called cytokines to coordinate the immune response. These cells are essential for both the adaptive immune response and the overall defense against pathogens. There are different subsets of T helper cells, including Th1 and Th2, each with distinct functions in managing immune reactions and ensuring the body can fight off various infections.