Effect of interleukin-13 or tumor necrosis factor-alpha on eosinophil adhesion to endothelial cells under physiological flow conditions.

Rationale: We examined the mechanisms used by eosinophils to accumulate on IL-13- or TNF-alpha-stimulated human umbilical vein endothelial cells (HUVECs) under flow conditions.

Methods: HUVECs were treated for 1, 3, 6, 18 and 24 h with IL-13 or TNF-alpha (1-100 ng/ml). Human eosinophils were infused at physiologic flow rates (0.5 dyn/cm(2)) for 10 min, and attached eosinophils were counted.

Results: Under these flow conditions, eosinophils accumulated efficiently on IL-13-stimulated (109 +/- 18 cells/field) or TNF-alpha-stimulated (96 +/- 27 cells/field) HUVECs in a concentration-dependent manner. Eosinophil accumulation on IL-13-activated HUVECs was first observed at 3 h and reached a maximum at 24 h. On the other hand, the levels of eosinophils accumulating on TNF-alpha-activated HUVECs were the same at all time points (1, 3, 6, 18 and 24 h). Anti-alpha4 integrin mAb inhibited eosinophil accumulation on both IL-13- and TNF-alpha-activated HUVECs.

Conclusions: Eosinophil accumulation on HUVECs under physiologic flow conditions is differentially regulated by IL-13 and TNF-alpha.