Endoplasmic reticulum stress drives a regulatory phenotype in human T-cell clones.

T cells alter their functional phenotype during the evolution of an immune response (intra-lineage differentiation), but the driving forces to this plastic intra-lineage differentiation are poorly understood. The endoplasmic reticulum (ER) stress response is a possible critical event for the initial T cell differentiation upon antigen recognition. Here we studied the relationship between ER and Il-10 transcription in human Treg clones. The induction of ER stress with a canonical stressor, thapsigargin, enhances Il-10 transcription. Salubrinal, a small molecule inhibitor of the eukaryotic translation initiation factor 2α (eIF2α) dephosphporylation, dramatically inhibits it. Il-10 transcription is also enhanced by exogenous TNFα. These results disclose a role for ER stress in driving T cell plasticity.