Allergen challenge of sensitized C57BL/6 mice induced impaired IL-4 and IL-5 release in comparison with Balb/c mice. Cytokine levels in BAL were determined by ELISA. Data are expressed as pg per μg of protein level. The Naïve group (open bar, Balb/c (n = 9) or light gray bar, C57BL/6 (n = 9)) received intranasal glycerol treatment alone. The Sensitized group (black bar, Balb/c (n = 12) or dark gray bar, C57BL/6 (n = 12)) received i.p. sensitization and i.n. treatment with Af extract. Data are expressed as Mean ± SEM, *p < 0.05 Sensitized vs Naive; #p < 0.05 C57BL/6 vs Balb/c.