Background. Pollen is the main cause of respiratory allergy and its prevalence is increasing. Timothy grass (Phleum pratense) is one of the most common pollen sources, and one of the best characterized allergenic grasses. The major allergens Phl p1, Phl p2, Phl p5 and Phl p6 are considered markers of genuine grass pollen sensitization. Methods. Retrospective study. IgE levels of Phl p1 and Phl p5 in patients living in the North-Central region of Portugal were analyzed, considering age and area of residence (inland or costal). Results. Among the 188 patients with IgE results for Phl p1 and Phl p5, sensitization to Phl p1 and Phl p5b was observed in 97.87% and 63.83%, respectively. The majority demonstrated co-sensitization to both Phl p1 and Phl p5b, while 68 patients were monosensitized to Phl p1 and 4 patients were monosensitized to Phl p5b. Either patients living in costal or inland areas showed IgE levels of Phl p1 higher than Phl p5b. Conclusions. Regarding genuine grass pollen sensitization, Phl p1 sensitization is more prevalent than Phl p5b in the North-Central region of Portugal.
Keywords: Grass pollen allergy; Phl p1; Phl p5b; Phleum pratense; timothy grass.