A Comprehensive Review on T Cells, B Cells, Natural Killer Cells, and Dendritic Cells Exhaustion: From Main Concepts to Clinical Use

During chronic infections, a distinct physiological condition named “exhaustion” arises that is associated with the dysfunctionality in immune cells and their eventual removal from the environment, which evidently help the progress of infection or tumors in human or animal bodies. This state of immune cells could be under the control of different elements such as the antigen load, help from inhibitory cells, lack of costimulatory signals and etc. Exhaustion that has been found in different immune system cells, is usually accompanied by impaired effector function and proliferation of immune cells, poor memory recall, upregulation of inhibitory molecules, compromised metabolism and altered transcription program, and is considered a reversible process, unlike other physiological states like anergy or senescence, organized through the blockage of several factors. Although the emergence of these cells in viral infections and cancer is an undesirable event, the importance of the presence of exhausted cells in autoimmune diseases and organ transplantation is highlighted as a positive change. In this review, we aimed to determine the occurrence of this process in different immune cells, the characteristics obtained by these cells, effective and primitive factors on exhaustion, metabolic and transcriptional cell changes, and the use of these cells in autoimmune diseases and organ transplantation.