Human <scp>CD</scp>8⁺<scp>EMRA</scp> T cells display a senescence‐associated secretory phenotype regulated by p38 <scp>MAPK</scp>

Summary Cellular senescence(definition) is accompanied by a senescence‐associated secretory phenotype ( SASP ). We show here that primary human senescent CD 8 + T cells also display a SASP comprising chemokines, cytokines and extracellular matrix remodelling proteases that are unique to this subset and contribute to age‐associated inflammation. We found the CD 8 + CD 45 RA + CD 27 − EMRA subset to be the most heterogeneous, with a population aligning with the naïve T cells and another with a closer association to the effector memory subset. However, despite the differing processes that give rise to these senescent CD 8 + T cells once generated, they both adopt a unique secretory profile with no commonality to any other subset, aligning more closely with senescence than quiescence. Furthermore, we also show that the SASP observed in senescent CD 8 + T cells is governed by p38 MAPK signalling.