Transforming growth factor-beta (TGF-beta), which can decrease the eff
ects of interleukin (IL)-3, IL-5 and granulocyte-macrophage colony-sti
mulating factor (GM-CSF) on eosinophil viability, has been shown to be
chemotactic for neutrophils. However, there is little information on
its effects on eosinophil chemotaxis. Because TGF-beta has recently be
en found in increased concentrations in asthmatic sputum, we investiga
ted whether TGF-beta could influence eosinophil migration and eosinoph
il viability. Purified eosinophils from normal donors were incubated w
ith increasing concentrations of TGF-beta. Chemotaxis was measured wit
h a modified Boyden chamber technique. In addition, eosinophils were i
ncubated for 96 h with either IL-3, IL-5 or GM-CSF (1 ng/ml) together
with increasing concentrations of TGF-beta. Eosinophil viability was t
hen determined with propidium jodide and flowcytometry. Eosinophil che
motaxis was significantly increased in the presence of TGF-beta in con
centrations between 10(-9) and 10(-4) mu g/ml. The optimal concentrati
on of TGF-beta in this assay was between 10(-9) and 10(-8) mu g/ml. Th
e chemotactic effect of TGF-beta diminished when higher as well as low
er concentrations (between 10(-12) and 10(-3) mu g/ml) were employed.
In contrast, inhibition of eosinophil survival induced by IL-3, IL-5 a
nd GM-CSF reached its maximum at concentrations of TGF-beta between 10
(-4) and 10(-3) mu g/ml. From these data we conclude that TGF-beta in
low concentrations can induce eosinophil chemotaxis whereas higher con
centrations reduce eosinophil survival mediated by IL-3, IL-5 and GM-C
SF.