Acquired and natural memory T cells join forces at the mucosal front line

The intestine is fundamental for the uptake of fluids and nutrients, but it also provides a main entrance for pathogens. This unique challenge has imposed an important evolutionary drive for distinctive specialization of the mucosal defence mechanisms. A hallmark of the modern immune system is its ability to generate antigen-specific memory T cells, which can provide immediate, potent and long-lasting protection. The high demand for effective protection, which is also compatable with vital functions of the intestine, has ensured that unique subsets of memory T cells have evolved at the mucosal front line. This review discusses the various mucosal T-cell subsets, and the new insights we have gained in understanding their specific differentiation and unique functions.