T cell activation induces CuZn Superoxide Dismutase (SOD)-1 intracellular re-localization, production and secretion. [*Terrazzano G., Rubino V. co-first]

Reactive oxygen species (ROS) behave as second messengers in signal transduction for a series of receptor/ligand interactions. A major regulatory role is played by hydrogen peroxide (H2O2), more stable and able to freely diffuse through cell membranes. Copper-Zinc Superoxide Dismutase (CuZn-SOD)-1 is a cytosolic enzyme involved in scavenging oxygen radicals to H2O2 and molecular oxygen, thus representing a major cytosolic source of peroxides. Previous studies suggested that superoxide anion and H2O2 generation are involved in T cell receptor (TCR)-dependent signaling.Here,we describe that antigen-dependent activation of human T lymphocytes significantly increased extracellular SOD-1 levels in lymphocyte cultures. This effectwas accompanied by the synthesis of SOD-1-specificmRNA and by the induction of microvesicle SOD-1 secretion. It is of note that SOD-1 increased its concentration specifically in T cell population, while no significant changes were observed in the non-T cell counterpart. Moreover, confocal microscopy showed that antigen-dependent activation was able to modify SOD- 1 intracellular localization in T cells. Indeed, was observed a clear SOD-1 recruitment by TCR clusters. The ROS scavenger N-acetylcysteine (NAC) inhibited this phenomenon. Further studies are needed to define whether SOD-1-dependent superoxide/peroxide balance is relevant for regulation of T cell activation, as well as in the functional cross talk between immune effectors.