To assess the interaction between fibroblasts and eosinophils and the role this plays in asthma pathogenesis, Esnault and colleagues exposed human lung fibroblasts (HLFs) to CM from eosinophils isolated from patients with and without asthma which had been treated with IL-5 and IL-3 to induce degranulation (42). This evidence concerns the gene IL3 and asthma.