This book equips young immunologists and health professionals with a clear understanding of the fundamental concepts and roles of co-signal molecules and in addition presents the latest information on co-stimulation. The first part of the book is devoted to co-signal molecules and the regulation of T cells. Following an initial overview, subsequent chapters examine each co-signal molecule in turn and discuss the mechanisms by which co-signal molecules regulate the different types of T cell. The second part covers various clinical applications, including in autoimmune disease, neurological disorders, transplantation, graft-versus-host disease, and cancer immunotherapy. To date, co-stimulation blockade and co-inhibition blockade have shown beneficial effects and many additional clinical trials targeting co-signal molecules are ongoing. The mechanisms underlying these successful treatments are explained and the future therapeutic potential in the aforementioned diseases is evaluated. Co-signal Molecules in T Cell Activation will be a valuable reference guide to co-stimulation for basic and clinical researchers in the fields of both immunology and pharmaceutical science.