The Aeroallergen Exposome in Argentina: Geographical Heterogeneity and Molecular Sensitization Profiles in Allergic Rhinitis and Asthma

Background: The distribution of airborne allergens varies across climatic and ecological settings and may shape region-specific molecular sensitization profiles. Objective: To characterize component-level IgE sensitization in patients with allergic rhinitis and/or asthma recruited in four Argentine locations and to explore its relationship with clinical phenotype. Methods: This multicenter cross-sectional study included 377 patients with respiratory allergy and at least one positive skin prick test and/or positive sIgE. Serum specific IgE was measured using an ALEX multiplex. Regional profiles were summarized by allergen source and molecular component. The molecular sensitization burden across clinical phenotypes was assessed using Kruskal–Wallis tests and Spearman rank correlation. Results: The cohort comprised 100 patients from Buenos Aires, 105 from San Rafael-Mendoza, 62 from Santa Rosa-La Pampa, and 110 from Rosario-Santa Fe; 374 had allergic rhinitis and 186 had asthma. Mite components predominated in Buenos Aires, where Der p 1, Der p 2, Der p 23, and Der f 2. Rosario-Santa Fe and Santa Rosa-La Pampa showed intermediate mite sensitization. San Rafael-Mendoza displayed a pollen-dominant pattern, led by Ole e 1, Lol p 1, Phl p 1, and Sal k 1, together with the highest frequency of Alt a 1 recognition (32.4%). Fel d 1 was the leading epithelial component in all centers, whereas cockroach sensitization was infrequent and mainly represented by Bla g 9. Molecular sensitization burden differed across asthma phenotypes (p = 0.0127) and showed a weak positive monotonic association with asthma severity (Spearman ρ = 0.184, p = 0.0117). No corresponding association was observed for rhinitis (ρ = −0.067, p = 0.1949). Conclusions: Molecular profiling identified marked regional heterogeneity in aeroallergen sensitization across Argentina. These findings support geographically informed diagnostic assessment while emphasizing that molecular sensitization represents only one component of the broader allergen exposome.