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Updated: Oct 26, 2025

Noninvasive Sampling of Mucosal Lining Fluid for the Quantification of In Vivo Upper Airway Immune-mediator Levels
Published on: August 7, 2017
Differences and similarities between the upper and lower airway: focusing on innate immunity
1Department of Otorhinolaryngology, Yonsei University College of Medicine, Seoul, Korea; Global Research Laboratory for Allergic Airway Disease, Yonsei University College of Medicine, Seoul, Korea; The Airway Mucus Institute, Yonsei University College of Medicine, Seoul, Korea.
Abstract:
The nose is the first respiratory barrier to external pathogens, allergens, pollutants, or cigarette smoke, and vigorous immune responses are triggered when external pathogens come in contact with the nasal epithelium. The mucosal epithelial cells of the nose are essential to the innate immune response against external pathogens and transmit signals that modulate the adaptive immune response. The upper and lower airways share many physiological and immunological features, but there are also numerous differences. It is crucial to understand these differences and their contribution to pathophysiology in order to optimize treatments for inflammatory diseases of the respiratory tract. This review summarizes important differences in the embryological development, histological features, microbiota, immune responses, and cellular subtypes of mucosal epithelial cells of the nose and lungs.
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