STM:疟疾免疫反应利弊共存
根据生命科学研究快报报道,通常,感染疟疾的孩子出现继发感染时往往没有临床症状。最近研究人员发现,这可能部分由于特定免疫细胞的损耗:一种叫做γδT细胞(免疫细胞)的损耗减轻了受感染儿童的炎症反应。


经常感染疟疾的孩子出现继发感染时往往没有临床症状。美国加州大学旧金山分校的研究人员对这一现象进行了研究,发现这可能部分由于特定免疫细胞的损耗:一种叫做γδT细胞(免疫细胞)的损耗减轻了受感染儿童的炎症反应。这项研究2014年8月27日在线发表于 Science Translational Medicine。

乌干达是非洲饱受疟疾困扰的一个国家,其国民经常暴露于疟原虫中。研究人员收集了从婴儿期就一直处于监控下的78名4岁儿童的感染疟疾、临床症状和免疫反应等数据。1岁的时候,研究中的所有儿童每次感染都表现出疟疾的临床症状;4岁的时候,不到10%的儿童感染后无症状;但1年后,超过20%的儿童感染后无症状。经研究发现,γδT细胞数量比较少的孩子容易被感染并成为疟原虫携带者。他们不容易表现出临床症状,比如发烧。另外,相关抗疟原虫免疫反应特定基因也很少被激活。

γδT细胞的缺失似乎在某些方面是有益的,然而有些方面也是有害的。人们可能不再受症状的困扰,也可能无法清除疟原虫,即其携带疟原虫又可通过蚊子进一步扩散。因而研究人员认为,与疟原虫Plasmodium falciparum初次感染相关的免疫反应或许有助于清除血液中的疟原虫,而这一免疫反应同时也具有导致严重贫血、脑型疟疾,甚至死亡等不利影响。

研究人员推测,疟疾感染通过重塑免疫反应,可能影响对其他传染病的敏感性和保护度。

管兴华 编译

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