Our research focuses on the function of different types of human memory and regulatory T cells. CD4+ memory and regulatory T cells are highly heterogeneous populations that can be sub-divided into various subsets with different functions. In particular, memory T cells secrete different types of effector cytokines and can be classified into IFN- secreting Th 1 cells, which activate phagocytes to eliminate intracellular bacteria and viruses, IL-4 secreting Th 2 cells that promote IgE production and eosinophil activation to fight parasitic worms, and IL-17 producing Th 17 cells that induce the recruitment of neutrophils to kill extracellular bacteria and fungi. Conversely, regulatory T cells (Tregs) suppress immune responses and inhibit autoimmunity in mouse models, and possess therefore therapeutic potential in autoimmune diseases. They can be subdivided into natural Tregs, which become committed to the Treg lineage already upon thymic maturation, and into adaptive ones, which acquire regulatory properties upon tolerogenic priming in the periphery. The latter contain IL-10 producing regulatory T cell subsets, which suppress immune responses via the potent antiinflammatory cytokine IL-10. IL-10 producing T cells in the human are studied nearly exclusively following induction or expansion in vitro with different protocols, which strongly alters the properties of T cells. It is therefore important to study IL-10 producing T cells directly ex vivo, and we were recently the fi rst to identify and characterize regulatory, IL-10 producing T cell subsets that were isolated directly ex vivo from human peripheral blood (Häringer et al. J Exp Med 2009, Rivino et al. J Exp Med 2010). In order to use “real” IL-10 producing regulatory cells in clinical trials, it is important to identify surface markers that allow their isolation and to further characterize their properties. We are currently trying to identify more specific surface markers for these subsets, study their regulation by transcription factors and monitor their presence in different pathologies in lymphoid and non-lymphoid tissues. The research group was dissolved after 4 years in July 2010, since we have moved to the National Institute of Molecular Genetics (INGM) in Milan, Italy,
where we continue to study the biology of human regulatory T cell subsets.