Nalt

NALT, or nasal-associated lymphoid tissue, is a component of the mucosa-associated lymphoid tissue (MALT) that plays a role in initiating immune responses to inhaled antigens. In many mammals, NALT is organized as discrete lymphoid structures in parts of the nasal cavity or nasopharynx; in humans, evidence supports a diffuse population of lymphoid tissue in the nasal mucosa rather than a single, well-defined organ, though it functions similarly to other MALT sites.

Cellular composition includes B and T lymphocytes, dendritic cells, macrophages, and specialized epithelial cells. M cells or follicle-associated epithelium may sample antigens from the nasal lumen and deliver them to underlying immune cells. B cells can differentiate into IgA-secreting plasma cells, contributing to secretory IgA in nasal secretions; germinal centers may form in organized NALT, especially in animals.

Functionally, NALT detects inhaled pathogens and antigens and initiates adaptive immune responses, including mucosal IgA production and T cell responses. It is important for protection against respiratory infections and for the effectiveness of intranasal vaccines.

Development and variation: NALT activity is present early in life and can be modulated by environmental exposure and infections; organization and prominence differ among species and individuals.

Clinical and research relevance: NALT is a consideration in mucosal vaccine design, including intranasal vaccines, and is studied in immunology and vaccine research as a route to elicit both local and systemic immunity.