Noronha F S, Ramalho-Pinto F J, Horta M F
Departamento de Bioquímica-Imunologia, Universidade Federal de Minas Gerais, Belo Horizonte, Brasil.
Braz J Med Biol Res. 1994 Feb;27(2):477-82.
Several organisms, including the protozoa Entamoeba histolytica and Trypanosoma cruzi, have been shown to contain pore-forming proteins (PFP) thought to play a role in the pathogenesis of the diseases they generate. In the present report, we show that promastigotes of Leishmania amazonensis express a hemolysin that appears to cause colloid-osmotic lysis, typical of pore formation. This hemolysin affects red blood cells of different species at 37 degrees C, but not at 0 degrees C, with maximum activity at pH 5.0. The hemolytic activity is heat-labile, but lysis is not affected by protease inhibitors. These results suggest the involvement of a protein with no proteolytic or detergent activity. Hemolysis is inhibited by polyethyleneglycol, suggesting its colloid-osmotic nature. Hemolytic extracts of the parasite contain a polypeptide that reacts with antibodies to perforin from mouse cytotoxic T lymphocytes or to C9 from human complement. In addition, genomic DNA of L. amazonensis contains a fragment that hybridizes to a perforin cDNA probe. The circumstantial evidence suggests that the L. amazonensis hemolytic activity may be mediated by a PFP homologous to perforin and C9.
包括原生动物溶组织内阿米巴和克氏锥虫在内的几种生物体，已被证明含有成孔蛋白（PFP），据认为这些蛋白在它们所引发疾病的发病机制中起作用。在本报告中，我们表明亚马逊利什曼原虫的前鞭毛体表达一种溶血素，该溶血素似乎会导致典型的成孔作用的胶体渗透裂解。这种溶血素在37℃时影响不同物种的红细胞，但在0℃时不影响，在pH 5.0时活性最高。溶血活性对热不稳定，但裂解不受蛋白酶抑制剂的影响。这些结果表明涉及一种没有蛋白水解或去污剂活性的蛋白质。溶血被聚乙二醇抑制，表明其胶体渗透性质。寄生虫的溶血提取物含有一种多肽，该多肽能与针对小鼠细胞毒性T淋巴细胞穿孔素或人补体C9的抗体发生反应。此外，亚马逊利什曼原虫的基因组DNA含有一个与穿孔素cDNA探针杂交的片段。间接证据表明，亚马逊利什曼原虫的溶血活性可能由与穿孔素和C9同源的PFP介导。
