Ortiz-Ordóñez J C, Seed J R
Department of Epidemiology, University of North Carolina, Chapel Hill 27599-7400, USA.
J Parasitol. 1995 Aug;81(4):555-8.
Susceptible African trypanosomes are lysed by a factor in human serum (HS), which presumably binds to their surface and is then internalized. It has been suggested that internalization of the factor is required for lysis. The hypothesis predicted that if the trypanolytic factor (TLF) binds and is endocytosed by trypanosomes, the lytic activity in HS should be removed by them. The experiments in this report have demonstrated that the lytic activity in HS can be almost completely removed. This was shown using both human serum sensitive (HSS) and resistant clones. As it might have been expected, HSS cells remove a greater percentage of the trypanolytic activity. In addition, the hypothesis also predicts that if the TLF is processed and activated from inside the trypanosome, its activity should be detected in the lysates of thoroughly washed trypanosomes previously incubated with HS. The results showed that the lysates consistently contained a soluble active form of the TLF that has been internalized by the trypanosomes. Antiserum specific to human high-density lipoprotein was found to neutralize the trypanolytic activity present in the lysates but failed to prevent the lysis of trypanosomes already exposed to HS.
易感性非洲锥虫会被人血清（HS）中的一种因子裂解，该因子可能会结合到锥虫表面，随后被内化。有人提出，因子的内化是裂解所必需的。该假说预测，如果锥虫溶解因子（TLF）与锥虫结合并被其胞吞，那么人血清中的裂解活性应该会被锥虫消除。本报告中的实验表明，人血清中的裂解活性几乎可以被完全消除。这在人血清敏感（HSS）克隆和抗性克隆中均得到了证实。不出所料，HSS细胞消除的锥虫溶解活性百分比更高。此外，该假说还预测，如果TLF在锥虫内部被加工并激活，那么在先前与人血清孵育过的彻底洗涤过的锥虫裂解物中应该能检测到其活性。结果表明，裂解物中始终含有一种已被锥虫内化的可溶性活性形式的TLF。发现针对人高密度脂蛋白的抗血清能中和裂解物中存在的锥虫溶解活性，但无法阻止已经接触过人血清的锥虫被裂解。
