Granulocyte macrophage-colony-stimulating factor mRNA is stabilized in airway eosinophils and peripheral blood eosinophils activated by TNF-α plus fibronectin

Airway eosinophils show prolonged in vitro survival compared with peripheral blood eosinophils (PBEos). Recent studies have shown that autocrine production and release of GM-CSF is responsible for enhanced survival, but the mechanisms controlling cytokine production remain obscure. We compared GM-CSF mRNA decay in eosinophils from bronchoalveolar lavage (BALEos) after allergen challenge or from PBEos. BALEos showed prolonged survival in vitro (60% at 4 days) and expressed GM-CSF mRNA. The enhanced survival of BALEos was 75% inhibited at 6 days by neutralizing anti-GM-CSF Ab. Based on transfection studies, GM-CSF mRNA was 2.5 times more stable in BALEos than in control PBEos. Treatment of PBEos with fibronectin and TNF-α increased their in vitro survival, GM-CSF mRNA expression, and GM-CSF mRNA stability to a comparable level as seen in BALEos. These data suggest that TNF-α plus fibronectin may increase eosinophil survival in vivo by controlling GM-CSF production at a posttranscriptional level.