Melo R C, Machado C R
Laboratory of Cellular Biology, Federal University of Juiz de Fora (UFJF), Juiz de Fora, MG, 36036-330, Brazil.
Exp Parasitol. 2001 Jan;97(1):15-23. doi: 10.1006/expr.2000.4576.
The contribution of mononuclear phagocytes to host resistance against acute Chagas disease has been studied in vivo in a rat model inoculated with Trypanosoma cruzi, Y strain. Acute T. cruzi infection triggered a dramatic increase (937%) in peripheral blood monocyte number at day 12 of infection. At this point, histological analysis of the heart showed high parasitism and diffuse and a moderate to intense mononuclear inflammatory process. Ultrastructural study revealed a large number of macrophages, in addition to lymphocytes and undiffer entiated cells. Clusters of macrophages exhibited different morphologi cal phenotypes, with evident signs of activation (increase in size, surface rufflings, and amount of cytoplasmic organelles). Cell-to-cell contacts involving macrophages and lymphocytes or macrophages and mono cytes were observed. Depletion of macrophages by treatment with silica, a selective cytotoxic agent for these cells, caused a significant increase in the number of amastigote nests in cardiomyocytes. The present findings indicate that the early phase of infection with T. cruzi induces rapid production, maturation, and activation of the monocyte/macrophage system so as to control T. cruzi replication, emphasizing the crucial role for macrophages in the rat resistance to Chagas disease.
在接种克氏锥虫Y株的大鼠模型中，已对单核吞噬细胞在宿主抵抗急性恰加斯病中的作用进行了体内研究。急性克氏锥虫感染在感染第12天时引发外周血单核细胞数量急剧增加（937%）。此时，心脏的组织学分析显示寄生虫感染严重，且存在弥漫性、中度至重度的单核细胞炎症过程。超微结构研究显示，除淋巴细胞和未分化细胞外，还有大量巨噬细胞。巨噬细胞簇呈现出不同的形态学表型，具有明显的活化迹象（细胞大小增加、表面褶皱以及细胞质细胞器数量增多）。观察到巨噬细胞与淋巴细胞或巨噬细胞与单核细胞之间存在细胞间接触。用二氧化硅（一种针对这些细胞的选择性细胞毒性剂）处理使巨噬细胞耗竭，导致心肌细胞中无鞭毛体巢数量显著增加。目前的研究结果表明，克氏锥虫感染的早期阶段会诱导单核细胞/巨噬细胞系统快速产生、成熟和活化，从而控制克氏锥虫的复制，强调了巨噬细胞在大鼠抵抗恰加斯病中的关键作用。
