SELL and obstructive sleep apnea syndrome: To our knowledge, the only study of γδTc in the context of hypoxia showed that circulating γδTc in patients with obstructive sleep apnea had elevated intracellular tumor necrosis factor alpha (TNFα) and IL-8 levels, increased TNFα and L-selectin-mediated adhesion properties, and enhanced cytotoxicity against endothelial cells compared to those isolated from healthy donors (46).