EFFECTS OF CERTAIN INFLAMMATORY MEDIATORS ON BOVINE NEUTROPHIL MIGRATION IN-VIVO AND IN-VITRO

Migration of bovine neutrophils towards endotoxin, recombinant bovine interleukin-1beta (rBoIL-1beta), recombinant human tumor necrosis fact or-alpha (rhTNF-alpha), platelet-activating factor (PAF), complement f actor C5a, leukotriene B4 (LTB4), and recombinant human interleukin-8 (rhIL-8) was studied in vivo, using the teat cistern model, and in vit ro using the modified Boyden chamber method. Infusion of endotoxin, rB oIL-1beta, rhTNF-alpha, PAF, or C5a into the teat cistern induced sign ificant accumulation of leukocytes, mainly neutrophils, during the sam pling period. Endotoxin was, on a molar basis, the most potent inducer of cell accumulation in vivo, followed by rBoIL-1beta, while C5a, PAF and rhTNF-alpha were less potent. No significant cell accumulation wa s observed after infusion of LTB4 or rhIL-8. A significant migration o f cells into the teat cistern was first observed 2 h after the infusio n of endotoxin or rBoIL-1beta, the rBoIL-1beta-induced response starte d somewhat earlier. The first significant cell accumulation after infu sion of PAF or C5a was observed already 1.5 h post infusion. The large st numbers of cells were reached 2.5-4.5 h after the infusion of endot oxin, rBoIL-1beta, rhTNF-alpha, PAF or C5a. In vitro, significant migr ation of bovine blood neutrophils was observed towards C5a or rhIL-8, and to a lower extent towards LTB4, while no chemotactic response to e ndotoxin, rBoIL-1beta rhTNF-alpha, and PAF was observed. Possible role s of the different substances as inducers of neutrophil migration into the bovine teat are discussed.