The book "CD4+CD25+ Regulatory T Cells: Origin, Function and Therapeutic Potential" offers a comprehensive analysis of the role of regulatory T cells in the immune system of vertebrates. It highlights the mechanisms that lead to self-tolerance and examines the significance of CD4+CD25+ T cells, known as natural regulatory T cells. These cells are crucial for maintaining immune homeostasis and play an essential role in preventing autoimmune diseases as well as in controlling infections and allergies. The book traces the development of these cells from their origin in the thymus to their site of action in peripheral lymphoid organs and tissues. It provides valuable insights into the mechanisms of dominant tolerance and their therapeutic potential, particularly concerning autoimmune diseases, cancer immunotherapy, and transplant survival.