Department of Microbiology and Immunology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
Eur J Immunol. 2011 May;41(5):1365-75. doi: 10.1002/eji.201040942.
Both iron-deficient anemia (IDA) and malaria remain a threat to children in developing countries. Children with IDA are resistant to malaria, but the reasons for this are unknown. In this study, we addressed the mechanisms underlying the protection against malaria observed in IDA individuals using a rodent malaria parasite, Plasmodium yoelii (Py). We showed that the intra-erythrocytic proliferation and amplification of Py parasites were not suppressed in IDA erythrocytes and immune responses specific for Py parasites were not enhanced in IDA mice. We also found that parasitized IDA cells were more susceptible to engulfment by phagocytes in vitro than control cells, resulting in rapid clearance of parasitized cells and that protection of IDA mice from malaria was abrogated by inhibiting phagocytosis. One possible reason for this rapid clearance might be increased exposure of phosphatidylserine at the outer leaflet of parasitized IDA erythrocytes. The results of this study suggest that parasitized IDA erythrocytes are eliminated by phagocytic cells, which sense alterations in the membrane structure of parasitized IDA erythrocytes.
缺铁性贫血 (IDA) 和疟疾仍然是发展中国家儿童面临的威胁。患有 IDA 的儿童对疟疾有抵抗力，但原因尚不清楚。在这项研究中，我们使用啮齿动物疟原虫 Plasmodium yoelii (Py) 来研究 IDA 个体中观察到的抗疟疾保护机制。我们表明，Py 寄生虫在 IDA 红细胞内的增殖和扩增并未受到抑制，并且 IDA 小鼠针对 Py 寄生虫的免疫反应也未增强。我们还发现，体外寄生虫感染的 IDA 细胞比对照细胞更容易被吞噬细胞吞噬，导致寄生虫感染细胞迅速清除，并且吞噬作用的抑制会破坏 IDA 小鼠免受疟疾的保护。这种快速清除的一个可能原因是寄生虫感染的 IDA 红细胞外层磷脂酰丝氨酸的暴露增加。这项研究的结果表明，吞噬细胞清除了寄生虫感染的 IDA 红细胞，吞噬细胞可以感知寄生虫感染的 IDA 红细胞膜结构的变化。
