Regulatory T Cells: Central Concepts from Ontogeny to Therapy

- Core concepts of Treg differentiation and function.
- Antigen specificity and lineage stability are important considerations in Tregs.
- Quantitative and qualitative defects in Tregs lead to disease.
- Systemic and cellular therapies can address Treg defects.
- Unique potential of cellular Treg therapies.

The balanced differentiation of naive CD4+ T cells into either pro- or anti-inflammatory fates is a central regulator of immune homeostasis, dysregulation of which can lead to inflammatory disease or cancer. Accordingly, the development of diagnostics and therapeutics to measure and modulate this balance is of great interest. In this review, we focus on the predominant anti-inflammatory subset, regulatory T cells, discussing key concepts including development, function, antigen specificity, and lineage stability. In particular, we highlight how these notions are shaping the evolution of therapeutics, especially in the context of the transfusion medicine specialist, and identify several key areas that urgently need to be addressed.