Barbara Bathke

Introduction Mucosal immunity plays a central role for defending the body against a wide range of pathogens that enter through mucosal surfaces, such as the respiratory, gastrointestinal, and urogenital tracts. These sites serve as major portals for infection, making the mucosal immune system the first line of defense.

The immunological outcome of infections and vaccinations is largely determined during the initial first days in which antigen‐presenting cells instruct T cells to expand and differentiate into effector and memory cells. Besides the essential stimulation of the T‐cell receptor complex a plethora of co‐stimulatory signals not only ensures a proper T‐cell activation but also instils phenotypic and functional characteristics in the T cells appropriate to fight off the invading pathogen.

The immunological outcome of infections and vaccinations is largely determined during the initial first days in which antigen-presenting cells instruct T cells to expand and differentiate into effector and memory cells. Besides the essential stimulation of the T cell receptor complex a plethora of co-stimulatory signals not only ensures a proper T cell activation but also instils phenotypic and functional characteristics in the T cells appropriate to fight off the invading pathogen.