An abnormally elevated proportion of exhausted T cells (Tex) among circulating T cells. T cell exhaustion is a distinct differentiation state that can be distinguished from naive, effector, and memory T cells. Compared to effector (TE) and memory (TMEM) T cells, exhausted T cells (TEX) display impaired effector functions (e.g., rapid production of effector cytokines, cytotoxicity). TEX have limited proliferative potential, especially compared to some subsets of TMEM and naive T cells. [from
HPO]