[Type I hypersensitivity to graminea pollens by tribe, in allergic rhinitis patients].

Type I Hypersensitivity to pollens of the Poaceae Family (Gramineae) organized by subfamilies and tribes were studied in 404 Costa Rican patients with a clinical diagnosis of Allergic Rhinitis and 100 non atopic subjects. Skin prick tests (for each tribe) were done with pooled samples from the species which are most abundant in Costa Rica (1/10 W/V, 50% glycerinated). The tribes were: Paniceae, Andropogoneae, Poeae, Aveneae, Oryzoideae and Chloridoideae (Eragrostoideae); 53% of the patients were positive to at least one of the tribes against 2% of the non atopic subjects. The most frequent tribe was the Aveneae with a 37.4% of positivity; the lowest was Paniceae with an 24.8% positivity. The provinces with the highest positivities to graminean pollens were Alajuela and Guanacaste with more than 60% of the rhinitic patients positive for at least one test. When an individual is positive to one tribe, it does not mean that this patient is positive to other tribes of this large Family. It is necessary to include all the tribes of the Poaceae Family present in a country or region to properly analyze allergic hypersensitivity to this family.