Interleukin-2 activates human peripheral blood eosinophils

The effect of interleukin (IL)-2 on eosinophil survival and mediator releas e was investigated in vitro. Human peripheral blood eosinophils were isolat ed and purified from mildly atopic donors and cultured on albumin-coated we lls with different concentrations of IL-2, interferon (IFN)-gamma, and gran ulocyte-macrophage colony stimulating factor (GM-CSF) and their viability w as evaluated after 4 days in culture. Eosinophils were cultured with IL-2 ( 1000 u/ml), IFN-gamma (1000 u/ml), or GM-CSF (10 ng/ml) for 18 h, or with p latelet activating factor (PAF) (10(-6) M) for 20 min, and the release of e osinophil peroxidase (EPO) and IL-6 was measured. Nedocromil sodium (10(-5) M) was added with each of the above cytokines to study the inhibitory effe ct of this drug on EPO release. A significant increase of EPO release was i nduced by IL-2, IFN-gamma, and GM-CSF after 18 h in culture. IL-2 as well a s IFN-gamma induced a significant IL-6 release from eosinophils. Nedocromil sodium significantly inhibited EPO release from eosinophils induced by IL- 2 or PAF. These results show that IL-2 can activate peripheral blood eosino phils, to release granule mediators (EPO) and cytokines, (IL-6). Taken toge ther with the presence of IL-2 receptors on eosinophils, we conclude that I L-2 is an important mediator in allergic inflammation and a possible target for pharmacological modulation. (C) 2001 Academic Press.