11月版的American Journal of Pathology杂志上发表了澳大利亚Alberta大学研究人员有关嗜酸性粒细胞(eosinophil)在免疫发育过程中重要作用的研究论文。
当免疫系统对环境中无害的物质如花粉或霉菌产生不正常应答时，常常导致哮喘或过敏性疾病发生。常见的过敏性疾病有，湿疹，荨麻疹，花粉热，哮喘，食物过敏等。
根据接受刺激后产生炎症的类型和分泌物，可以将免疫应答分为Th1型和Th2型。Th1免疫应答一般针对细胞内感染，如细菌或病毒感染。而Th2免疫应答则针对较大的寄生虫，如线虫感染。而哮喘和过敏性疾病通常是由于产生了不正常的Th2免疫应答。
虽然嗜酸性粒细胞作为一种免疫细胞，一直被认为可以调节过敏反应以及哮喘Th2免疫应答，同时也可能是控制Th1 和Th2免疫应答的重要开关。因此，研究人员对儿童胸腺中嗜酸性粒细胞发育进行研究。胸腺是人体的免疫器官，也是早期Th1/Th2分化的场所，随着年龄的增长会逐渐萎缩。研究表明，胸腺IDO+嗜酸性粒细胞(Thymic Indoleamine 2,3-Dioxygenase Positive Eosinophils)在人类婴儿期或许对Th2免疫应答具有免疫调节作用。（生物谷Bioon.com）
生物谷推荐原始出处：
American Journal of Pathology. 2009;175:2043-2052. DOI: 10.2353/ajpath.2009.090015
Thymic Indoleamine 2,3-Dioxygenase-Positive Eosinophils in Young Children
Potential Role In Maturation of the Naive Immune System
Meri K. Tulic*, Peter D. Sly, David Andrews, Maxine Crook, Francis Davoine?, Solomon O. Odemuyiwa?, Adrian Charles, Megan L. Hodder*, Susan L. Prescott*, Patrick G. Holt and Redwan Moqbel
From the School of Paediatric and Child Health,* and the Telethon Institute for Child Health Research, Centre for Child Health Research, University of Western Australia, Perth, Australia; the Divisions of Cardiac Surgery and Paediatric Pathology, PathWest Laboratory Medicine, Princess Margaret Hospital, Perth, Australia; and the Pulmonary Research Group,? University of Alberta, Edmonton, Canada
Eosinophils expressing indoleamine 2, 3-dioxygenase (IDO) may contribute to T-helper cell (Th)2 predominance. To characterize human thymus IDO+ eosinophil ontogeny relative to Th2 regulatory gene expression, we processed surgically obtained thymi from 22 children (age: 7 days to 12 years) for immunohistochemistry and molecular analysis, and measured cytokine and kynurenine levels in tissue homogenates. Luna+ eosinophils (2% of total thymic cells) decreased in number with age (P = 0.02) and were IDO+. Thymic IDO immunoreactivity (P = 0.01) and kynurenine concentration (P = 0.01) decreased with age as well. In addition, constitutively-expressed interleukin (IL)-5 and IL-13 in thymus supernatants was highest in youngest children. Eosinophil numbers correlated positively with expression of the Th2 cytokines IL-5, IL-13 (r = 0.44, P = 0.002), and IL-4 (r = 0.46, P = 0.005), transcription factor signal transducer and activator of transcription-6 (r = 0.68, P = 0.001), and the chemokine receptor, CCR3 (r = 0.17, P = 0.04), but negatively with IL-17 mRNA (r = –0.57, P = 0.02) and toll-like receptor 4 expression (r = –0.74, P = 0.002). Taken together, these results suggest that functional thymic IDO+ eosinophils during human infant life may have an immunomodulatory role in Th2 immune responses.
