Structure, Organization, and Development of the Mucosal Immune System of the Respiratory Tract

The respiratory tract is served by a variety of lymphoid tissues, including the tonsils, adenoids, nasal-associated lymphoid tissue (NALT), and bronchus-associated lymphoid tissue (BALT), as well as the lymph nodes that drain the upper and lower respiratory tract. Each of these tissues uses unique mechanisms to acquire antigens and respond to pathogens in the local environment and supports immune responses that are tailored to protect those locations. This chapter will review the important features of NALT and BALT and define how these tissues contribute to immunity in the upper and lower respiratory tract, respectively.