RNA-Seq of human regulatory T cells and effector T cells cultured at standard 37°C temperature and in mild hypothermia (33°C).

Regulatory T cells (Tregs) play crucial role in maintenance of peripheral tolerance. Numerous clinical trials confirmed safety and efficacy of Treg treatment of for deleterious immune responses. However, Tregs lose their characteristic phenotype and suppressive potential during expansion ex vivo. In our experiment we demonstrate that mild hypothermia of 33ºC induces robust proliferation of human Tregs, preserves expression of FoxP3, CD25 and Helios, and prevents TSDR methylation during culture in vitro. Tregs expanded at 33°C showed stronger immunosuppressive potential and anti-inflammatory phenotype. We show that a simple change in temperature can preserve Treg stability, function and accelerate their proliferation in vitro.