Effect of prolonged ovalbumin (OVA) challenge on levels of TGF-β. (a) Representative photomicrographs of paraffin-embedded lung sections from alum controls (i), OVA challenged mice at day 24 (ii), day 55 (iii) and day 80 (iv), stained with antibody against TGF-β1. Data is representative of n = 4/group/ time point. Ig controls were negative (original magnification × 40). (b) Levels of active TGF-β1 were measured in lung homogenates by ELISA taken from acute and chronic OVA challenged mice. Data is expressed as mean ± SEM, n = 5–10/group; *P<0.05 in comparison with alum control mice. (c) Levels of eotaxin were measured in lung tissue homogenates by ELISA from mice during prolonged allergen challenge. Data is expressed as mean ± SEM, n = 4/group; *P<0.05 in comparison with alum control mice.