Sensitization to subtropical grass pollens in patients with seasonal allergic rhinitis from Bahia Blanca, Argentina

Background: Grass pollinosis is an important contributor to allergic diseases, with varying patterns and frequency of allergens according to the geographical location studied. Our study aims to provide a better understanding of subtropical grass pollinosis in Argentinian patients with seasonal allergic rhinitis. Methods: We conducted a retrospective cross-sectional study involving 894 patients with seasonal allergic rhinitis from Bahía Blanca, Argentina. Skin prick tests were performed to selected pollen species belonging to three subfamilies of the Poaceae genera. Frequency of sensitization to specific grass pollen extracts, cross-reactivity of allergens assessed by skin prick test, and possible associations between allergen extracts and asthma or allergic conjunctivitis were analyzed. Results: Sensitization to the Pooideae subfamily was the most frequent, encompassing 86.8% (CI: 84.4%–88.9%) of the studied population. Positive reactions to allergen extracts from the Chloridoideae and the Panicoideae subfamilies showed smaller papule size than allergen extracts from the Pooideae subfamily (χ²(5) = 83.75, p < 0.001). Patients with a positive skin prick test (SPT) to a specific extract were more likely to present some degree of cross-reactivity to the remaining pollens when compared to patients with negative SPT to the same specific extract. Even though the proportion of patients presenting with asthma (46.9%) was higher than those with conjunctivitis (22.6%), there was only a statistically significant association between sensitization to Festuca arundinacea (φ = 0.089, p = .009), Phalaris arundinacea (φ = 0.074, p = .032) and Paspalum notatum (φ = 0.070, p = .038) and the presence of conjunctivitis. Conclusions: Our results suggest a high frequency of sensitization to grass pollen extracts from the Poaceae family among patients with seasonal allergic rhinitis. Overall, sensitization to the Pooidae subfamily was the most common, where Phalaris arundinacea presented the highest frequency.