nose-associated lymphoid tissue (NALT)
Loosely organized collections of LYMPH tissue embedded in the mucous membrane lining (mucosa) of the nasal passages and sinus cavities. Nasal mucous, which the nasal mucosa secretes, is one of the body’s front-line protective mechanisms, providing a physical barrier that repels or traps foreign substances such as BACTERIA, viruses, toxins, and inhaled particles. Many pathogens gain entry to the body through the NOSE. NALT contains numerous B-cell lymphocytes and T-cell lymphocytes that detect and respond to invading pathogens. Macrophages, eosinophils, and other phagocytic cells are also concentrated in NALT to clean up cellular debris that NALT traps or collects.
The mucous membrane lining of the nose is the first point of contact for inhaled allergens. Its mast cells quickly initiate an IMMUNE RESPONSE by releasing HISTAMINE and other biochemicals to stimulate LYMPHOCYTE activity. This HYPERSENSITIVITY REACTION results in the common symptoms of ALLERGIC RHINITIS (seasonal allergies). In 2003 the US Food and Drug Administration (FDA) approved the first nasal VACCINE for INFLUENZA (the flu). It was the first to capitalize on the immune response NALT can generate to provide systemic (bodywide) IMMUNITY for the influenza strains the vaccine contains.
For further discussion of NALT within the context of the structures and functions of the immune system, please see the overview section “The Immune System and Allergies.”
See also ALLERGEN; B-CELL LYMPHOCYTE; BRONCHUSASSOCIATED LYMPHOID TISSUE (BALT); COLDS; MACROPHAGE; MAST CELL; MUCOSA-ASSOCIATED LYMPHOID TISSUE (MALT); PATHOGEN; PHAGOCYTE; SKINASSOCIATED LYMPHOID TISSUE (SALT); SNEEZE; VASCULAR-ASSOCIATED LYMPHOID TISSUE (VALT); VIRUS.
