Clinkenbeard K D, Upton M L
Department of Veterinary Pathology, College of Veterinary Medicine, Oklahoma State University, Stillwater 74078.
Am J Vet Res. 1991 Mar;52(3):453-7.
Pasteurella haemolytica A1 culture supernatants caused rapid cytolysis (less than 5 minutes) of isolated bovine platelets as measured by leakage of the cytoplasmic enzyme lactate dehydrogenase (LD). The platelet lytic factor had several features similar to P haemolytica leukotoxin. Like P haemolytica leukotoxin, the platelet lytic factor was produced by P haemolytica during logarithmic growth phase, was heat-labile, and was active against target cells (platelets) from ruminant species (cattle and sheep), but not from non-ruminant species (horses, pigs, and human beings). Additionally, the platelet lytic factor was neutralized with antileukotoxin rabbit serum. The amount of LD leaked by a fixed concentration of bovine platelets was proportional to the amount of toxin added at low toxic doses and became maximal at 88 +/- 11% of the total platelet LD activity for high doses of toxin. When a fixed dose of toxin was used and the platelet concentration was varied, LD leakage was initially proportional to the platelet concentration, but plateaued at higher platelet concentrations. The platelet lytic factor required Ca2+ and was inhibited by addition of the Ca2+ chelator ethylene glycol-bis(beta-aminoethyl ether)N,N,N',N'-tetraacetic acid. Toxin-mediated platelet damage may be important in thrombi formation and fibrin exudation typically associated with P haemolytica pleuropneumonia of cattle.
溶血巴斯德菌A1培养上清液可导致分离出的牛血小板迅速发生细胞溶解（少于5分钟），这通过细胞质酶乳酸脱氢酶（LD）的泄漏来测定。血小板溶解因子具有一些与溶血巴斯德菌白细胞毒素相似的特征。与溶血巴斯德菌白细胞毒素一样，血小板溶解因子由溶血巴斯德菌在对数生长期产生，对热不稳定，并且对反刍动物（牛和羊）的靶细胞（血小板）有活性，但对非反刍动物（马、猪和人类）的靶细胞无活性。此外，血小板溶解因子可用抗白细胞毒素兔血清中和。在低毒剂量下，固定浓度的牛血小板泄漏的LD量与添加的毒素量成正比，而在高剂量毒素时，泄漏量达到血小板总LD活性的88±11%时达到最大值。当使用固定剂量的毒素并改变血小板浓度时，LD泄漏最初与血小板浓度成正比，但在较高血小板浓度时趋于平稳。血小板溶解因子需要Ca2+，并可被添加Ca2+螯合剂乙二醇双（β-氨基乙醚）N,N,N',N'-四乙酸所抑制。毒素介导的血小板损伤可能在通常与牛溶血巴斯德菌胸膜肺炎相关的血栓形成和纤维蛋白渗出中起重要作用。
