Final answer:
Th1 cells secrete IL-2 to enhance the activity of macrophages and other T cells.
Step-by-step explanation:
Th1 cells are a type of helper T cell that secrete cytokines to enhance the activity of macrophages and other T cells. These cytokines, including IL-2, regulate the immunological activity and development of various cells. For example, IL-2 helps in the proliferation of T cells and the activation of cytotoxic T lymphocytes, leading to an improved immune response against pathogens.
Th1 cells are differentiated from other T helper cells by the cytokines they produce, and their presence is critical in the body's ability to fight off certain types of infections.