Effect of Interleukin-13 or Tumor Necrosis Factor-Alpha on Eosinophil Adhesion to Endothelial Cells under Physiological Flow Conditions

Abstract

Rationale: We examined the mechanisms used by eosinophils to accumulate on IL-13- or TNF-α-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-α (1–100 ng/ml). Human eosinophils were infused at physiologic flow rates (0.5 dyn/cm²) 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-α-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-α-activated HUVECs were the same at all time points (1, 3, 6, 18 and 24 h). Anti-α4 integrin mAb inhibited eosinophil accumulation on both IL-13- and TNF-α-activated HUVECs. Conclusions: Eosinophil accumulation on HUVECs under physiologic flow conditions is differentially regulated by IL-13 and TNF-α.