Mechanisms involved in the expansion of Tregs during pregnancy: role of IL-2/STAT5 signalling

Several studies have reported that the fine-tuning of regulatory T cells (Tregs) is required for a successful pregnancy and for the control of autoimmune diseases. Here, we review the mechanisms that control the expansion of Tregs, based on insights obtained from the study of women suffering unsuccessful pregnancies and on recent data from patients with autoimmune diseases or with chronic viral infections such as HCV. In particular, we review the role of endocrine factors and IL-2/STAT5 signalling in the impaired expansion of Tregs.