Potential Utility of Nasal Lavage Microparticle Analysis in the Diagnosis and Pathophysiology of Local Allergic Rhinitis

Released microparticles (MP) from injured or activated cells have been proposed as biomarkers in different clinical samples. We compared changes in MP levels in nasal lavage fluid (NLF) before and after nasal allergen provocation tests (NAPTs) in patients with local allergic rhinitis (LAR) and non-AR. 14 patients with chronic nasal symptoms and negative tests for systemic atopy underwent 26 NAPTs to perennial allergens. Microparticle levels derived from activated mast cells (CD137(+)FcεRI(+)c-kit(+)MPs), activated basophils (CD63(+)CD203c(+)c-kit(-)MPs), activated eosinophils (CD69(+)EMR1(+)MPs) and epithelial cells (EpCAM(+)MPs) were measured by flow-cytometry in 17 NLF samples, before and 15 minutes after NAPTs (7 samples from positive NAPTs [LAR] and 10 from negative NAPTs [non-AR]). In NLF samples obtained from positive NAPTs (LAR patients), certain MP levels were significantly elevated at 15 minutes after NAPTs compared with baseline: activated mast cell MPs (2.1-fold increase, p=0.02), activated basophil MPs (2.6-fold increase, p=0.02) and epithelial MPs (2.1-fold increase, p=0.01). However, there was no change in these three MP levels at 15 minutes after negative NAPTs (non-AR patients) compared with baseline (activated mast cell MPs: p=0.13, activated basophil MPs: p=0.6, epithelial MPs: p=0.16). Interestingly, we did not find a change in levels of activated eosinophil MPs after either positive (p=0.38) or negative (p=0.31) NAPTs. Based on MP levels analysis, epithelial injury is induced and mast cells and basophils get activated after positive NAPTs in LAR patients, without evidence of eosinophils activation in this cohort. Measuring MPs in the NLF may be useful in both diagnosing LAR and better elucidating its pathophysiology.