3.3 IL-18与肠道寄生虫病的关系 目前 全球大约有10亿人受鞭虫（trichuris trichiura）感染。对天然发生于小鼠的与此相对应的Trichuris muris感染的 研究 揭示了对这种寄生虫的易感性和抵抗力的部分免疫调节机制［22］。在Th1介导的慢性肠道线虫感染的结肠黏膜有IL-18mRNA及其蛋白的表达。IL-18 KO小鼠对慢性肠道线虫感染有很强的抵抗力，并产生很强的抗原特异性Th2反应。对有天然抵抗力的小鼠给予重组IL-18，抑制抗原特异性的IL-13和IL-4分泌，并发生慢性炎症，而IFN-γ的水平并未受 影响 ，显示在慢性trichuris muris感染IL-18并不诱导IFN-γ的产生，而是直接作为Th2细胞因子如IL-13和（或）IL-4的负调节。这首次显示了IL-18在慢性肠道线虫感染中的重要致病作用。
4 结语
IL-18的研究进展很快，从发现至今对它的分子结构、基因表达及生物学作用的研究已有许多报道。IL-18是以促进Th1反应为主的细胞因子，在抗感染、免疫调节及抗肿瘤上有很大的潜在价值。它在肠疾病中作用的研究尚不充分。在以Th1反应为主的疾病中，降低IL-18活性可能是合理的 治疗 策略，然而其安全性尚需探讨。IL-18的抗肿瘤作用可能为肿瘤的生物学治疗提供新的途径。
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