TNF-alpha, IL-4, and IFN-gamma regulate differential expression of P and E-selectin expression by porcine aortic endothelial cells

P- and E-selectin are surface glycoproteins that mediate leukocyte rolling on the surface of endothelium in inflammation. We have cloned porcine P-sel ectin cDNA and generated a mAb, 12C5, with which to examine P-selectin expr ession by porcine aortic endothelial cells (PAEC) in comparison with that o f E selectin. Basal expression by PAEC of P-selectin was greater than that of E-selectin, whereas E-selectin expression was more prominently enhanced than that of P-selectin by stimulation with TNF-alpha or IL-1 alpha, Both h uman or porcine IL-4 led to an increase in P-selectin expression, with kine tics that were delayed compared with those seen following stimulation with TNF-alpha or IL-1 alpha, but IL-4 did not stimulate expression of E-selecti n, When cells were stimulated with TNF-alpha in the presence of IL-4, we ob served enhanced P-selectin expression with a parallel reduction in E-select in expression. Finally, the increase in P-selectin expression due to human IL-4 was reduced in the presence of porcine but not human IFN-gamma, These observations show that E-selectin and P-selectin expression are differentia lly regulated in PAEC, and that IL-4 leads to a shift in the relative surfa ce density of the two molecules toward P-selectin. The ability of porcine I FN-gamma to inhibit IL-il-induced P-selectin expression suggests that the b alance between Th1 and Th2 cytokine production may determine the relative d ensities of the two selectins in chronic immune-mediated inflammation. Beca use the increased expression of F-selectin induced by human IL-4 was not in hibited by human IFN-gamma, this balance may he shifted toward P-selectin e xpression in porcine xenografts infiltrated by human lymphocytes.