AAM are present in the lungs of chimeric mice receiving IL-4Rα+/+ bone-marrow. Balb/c IL-4RαxRAG2-/- mice were irradiated and reconstituted with bone-marrow cells isolated from IL-4Rα-/- or IL-4Rα+/+ mice as previously described . Six weeks later, the mice were provided with OVA specific TH2 effectors (1 × 107/mouse) by tail vein injection. They were then sensitized to 100 μg chicken egg ovalbumin (OVA) adsorbed to aluminum hydroxide (Alum) via i.p. injection on day 0 and boosted with the same reagent on day 14. Mice were exposed to 1% OVA in PBS by nebulization for 20 min each day on days 19, 22, and 27. Lung sections from OVA/alum primed mice were prepared and stained with H&E, anti-F4/80, anti-YM1/2, or control rabbit IgG as indicated. Digital images from a representative mouse (n = 4) for the 2 groups are shown (20X). These results are representative of 3 independent experiments.