Dust Mite-Specific IgE in Nasal Lavage Fluid During Natural Allergen Exposure and After Nasal Provocation Test in Subjects with Suspected Local Allergic Rhinitis

<b>Introduction:</b> Apart from the typical AR phenotype and its standard clinical manifestations-rhinorrhea, sneezing, nasal itching, and congestion-the so-called local allergic rhinitis (LAR) can be observed in a subset of subjects presenting rhinitis symptoms, a negative skin prick test (SPT), and serum-specific immunoglobulin E (sIgE) for the relevant allergens and confirmed with a positive nasal provocation test (NPT), which is the gold standard in LAR diagnosis. Our study aims to assess the clinical symptoms and local mucosal sIgE presence induced by NPT and natural exposure to HDM allergens in subjects with suspected LAR. <b>Methods:</b> In total, 25 suspected LAR subjects were included in the study. The total nasal symptom score (TNSS) and visual analog scale (VAS) were used for the subjective assessment. A nasal provocation test (NPT) was performed with house dust mite allergens. The nasal lavage technique was used for nasal secretion acquisition, in which the levels of sIgE were measured. <b>Results</b>: During the period of increased exposure vs. the off-exposure period, the TNSS and VAS were significantly higher (<i>p</i> = 0.0361 and <i>p</i> = 0.0031, respectively). Levels of IgE specific to <i>Dermatophagoides pteronyssinus</i> in nasal lavage were high (<i>p</i> = 0.0502). Similarly, high levels of sIgE to <i>Dermatophagoides farinae</i> were noted (<i>p</i> = 0.0164). Comparing pre-NPT and post-NPT results, LAR diagnosis was confirmed in 8 subjects. Only the VAS score was higher after a positive NPT. Both sIgE to <i>Dermatophagoides pteronyssinus</i> and <i>Dermatophagoides farinae</i> in nasal lavage were higher after a positive NPT; however, the change was not statistically significant. A higher fold change in the median relative value (sIgE/Total IgE) for both allergens was noted in the positive-NPT group compared to the negative-NPT group. <b>Conclusions:</b> Assessing the local nasal production of sIgE and other inflammatory mediators may contribute to expanding our knowledge of LAR pathogenesis. Further studies including a larger number of subjects are needed for a better understanding of the LAR entity in terms of diagnosis and treatment options.