IL-7, or Interleukin-7, is a type of protein known as a cytokine that plays a crucial role in the immune system. It is primarily produced by stromal cells in the bone marrow and thymus, and it helps in the development and survival of T cells and B cells, which are essential components of the adaptive immune response. This cytokine is vital for maintaining the homeostasis of lymphocytes, ensuring that the body can effectively respond to infections. Additionally, IL-7 has been studied for its potential therapeutic applications in treating various immune-related disorders and enhancing immune responses in cancer therapies.