IL5 and perennial allergic rhinitis: In comparing cytokine profiles between non-allergic patients and paucisymptomatic patients with perennial allergic rhinitis during natural exposure to allergens, without provocation, we observed an increase in IL-4 expression, a trend towards IL-5 expression increase, Th2-type citokines, no statistically significant difference in the expression of IFN-γ and Th-1-type cytokine, thus suggesting that the Th2-type response is crucial for the physiopathology of allergic rhinitis in vivo.