Unraveling the link between draught and upper respiratory mucosal immunity: Assessing lysozyme and S-lgA concentrations in nasal lavage fluid

Abstract

The purpose of this study is to investigate the effect of draught on upper respiratory tract mucosal immunity, by assessing concentrations of lysozyme and secretory immunoglobulin A (S-IgA) in nasal lavage fluid. A total of 26 subjects were recruited and experienced 4 experiment conditions combined with two ambient temperatures (24 °C and 28 °C) and two air velocities towards the nape (0 m/s and 1 m/s). Physiological parameters, and subjective questionnaires (i.e., thermal sensation vote (TSV), thermal comfort vote (TCV), and air movement vote (AMV)) were also collected. Our findings revealed that physiological parameters fluctuated significantly under 24 °C, 1 m/s (p < 0.05). Significant decreases in lysozyme concentration occurred under both 24 °C, 1 m/s (p = 0.003) and 24 °C, 0 m/s (p = 0.017). S-IgA concentrations significantly decreased after one-day lag (p = 0.028) under 24 °C, 1 m/s. When TSV deviated from neutral, lysozyme concentrations decreased, especially when the TSV was [-3, −1.5) (p = 0.01). The S-IgA concentration increased when subjects felt slightly uncomfortable and decreased steadily for further discomfort. The proportion of subjects with decreased immune biomarker levels was minimized in the neutral TSV zone. The findings suggest that under the investigated scenarios, cold draught can suppress respiratory immunity by altering thermal sensations, with effects potentially persisting beyond exposure duration. Ensuring a neutral and comfortable thermal environment is pivotal for maintaining immunity stability. However, more experiments under a wider range of thermal parameters need to be performed to prove the robustness of current results.