Taiwo V O, Adejinmi J O, Oluwaniyi J O
Department of Veterinary Pathology, University of Ibadan, Nigeria.
Onderstepoort J Vet Res. 2002 Jun;69(2):155-61.
An in vitro assay that measures the generation of superoxide anions (O2-) was used to assess the level of oxidative burst of phorbol myristate acetate (PMA)- and trypanosome-stimulated neutrophils isolated from healthy Boran and N'Dama cattle, and those infected with Trypanosoma congolense. PMA stimulation of healthy bovine neutrophils resulted in between 300-400 % increase in O2- generation. Neutrophils of Boran cattle exhibited slightly higher but insignificant O2- generation capacity than those of the N'Dama breed. In vitro stimulation by trypanosomes of neutrophils isolated from Trypanosoma congolense-infected cattle caused significant increases in O2- generation, especially on days 14, 28 and 42 post-infection, of both breeds of cattle. No significant differences were observed in O2- generation capacity of the neutrophils of both breeds of infected cattle throughout the period of assay. The results of this study have shown that PMA and trypanosomes do cause an enhanced in vitro oxidative burst, hence trypanosome phagocytosis and killing activity of neutrophils. Neutrophils have been shown to play very significant roles in parasite clearance, hence reduction of trypanosome parasitaemia. The rates of both in vitro generation of O2- and trypanosome phagocytosis over time did not differ significantly between Boran and N'Dama breeds of cattle, even during T congolense infection in this study. Hence, it may be inferred that sustained and higher parasitaemia, more pronounced neutropenia, inadequate bone marrow response and less effective trypanosome-specific immune response, rather than defective neutrophil trypanosome destruction, may be the problem of trypanosusceptible cattle breeds.
采用一种测量超氧阴离子（O2-）生成的体外测定法，来评估从健康的博拉牛和恩达马牛以及感染刚果锥虫的牛中分离出的、经佛波酯肉豆蔻酸酯乙酸酯（PMA）和锥虫刺激的中性粒细胞的氧化爆发水平。对健康牛中性粒细胞进行PMA刺激后，O2-生成量增加了300%-400%。博拉牛的中性粒细胞表现出比恩达马品种略高但不显著的O2-生成能力。从感染刚果锥虫的牛中分离出的中性粒细胞经锥虫体外刺激后，两种牛的O2-生成均显著增加，尤其是在感染后第14、28和42天。在整个测定期间，两种感染牛的中性粒细胞的O2-生成能力未观察到显著差异。本研究结果表明，PMA和锥虫确实会导致体外氧化爆发增强，从而增强中性粒细胞的锥虫吞噬和杀伤活性。中性粒细胞已被证明在清除寄生虫中发挥非常重要的作用，从而降低锥虫血症。即使在本研究的刚果锥虫感染期间，博拉牛和恩达马牛品种之间，O2-的体外生成率和锥虫吞噬率随时间的变化也没有显著差异。因此，可以推断，持续且更高的寄生虫血症、更明显的中性粒细胞减少、骨髓反应不足以及锥虫特异性免疫反应效果较差，而非中性粒细胞对锥虫的破坏存在缺陷，可能是锥虫易感牛品种的问题所在。
