Transforming growth factor alpha expression in normal human blood eosinophils : differential regulation by granulocyte-macrophage colony-stimulating factor and interleukin-3

We have previously demonstrated a constitutive expression of transforming growth factor α (TGF-α) in normal human blood eosinophils, both at the mRNA and protein level. This may indicate a novel function of the eosinophil, the regulation of which has not been clarified. Therefore human white blood cells (WBC) were treated with potential regulators of eosinophil function. Northern blot analysis demonstrated that human recombinant granulocyte-macrophage colony-stimulating factor (GM-CSF) or interleukin-3 (IL-3) caused a time and dose-dependent 2- to 3-fold increase of TGF-α mRNA levels, in relation to incubation in the absence of cytokine; maximal response was attained within 4 h of incubation