Histology of β7 integrin-deficient and C57BL/6 mouse lung after OVA sensitization and 3 days of aerosolized OVA challenge. The lung from the β7 integrin-deficient mouse (left panel) shows leukocyte infiltration around the bronchovascular bundles, similar to that observed in lung from the wild-type C57BL/6 mouse treated in parallel (right panel).