人们普遍认为在自然环境中成长更有益于健康。近日，英国一项最新动物研究证实了这一点：在农场中自然成长的小猪，与在隔离室中成长的小猪相比，有更强的免疫调节能力。
英国布里斯托尔大学等机构研究人员在新一期《儿科过敏与免疫学》（Pediatric Allergy and Immunology）杂志上报告说，他们用一些刚出生的小猪进行了对比实验，一部分小猪在农场放养，另一部分一生下来就被放入隔离室，在非常干净的环境中喝配方奶粉长大。
一段时间后，研究人员对它们进行检查。结果，在农场长大的小猪，体内一种名为调节性T细胞的免疫细胞数量多于在隔离室中长大的小猪。调节性T细胞的功能是调节免疫系统，使其不随便产生免疫反应，以免引起不必要的疾病，比如对一些常见物质过敏等。
与调节性T细胞数量差异相应的是，在隔离室长大的小猪断奶时对一些新接触的豆类食物产生了不必要的免疫反应，而在农场中自然长大的小猪则表现良好。
研究人员玛丽·刘易斯说，人们常有一些经验性的感受，如在自然环境中长大的孩子不容易出现过敏症状，本次研究有力地证实了这种因果关系。调节性T细胞在人体内也存在并且发挥类似作用，孩子小时候的生活环境会影响他们体内这种细胞数量的多少，进而造成免疫功能上的差异。（生物谷Bioon.com）
doi:10.1111/j.1399-3038.2011.01258.x
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Direct experimental evidence that early‐life farm environment influences regulation of immune responses
Lewis, Marie C.; Inman, Charlotte F.; Patel, Dilip; Schmidt, Bettina; Mulder, Imke; Miller, Bevis; Gill, Bhupinder P.; Pluske, John; Kelly, Denise; Stokes, Christopher R.; Bailey, Michael
Background: In mammals, early-life environmental variations appear to affect microbial colonization and therefore competent immune development, and exposure to farm environments in infants has been inversely correlated with allergy development. Modelling these effects using manipulation of neonatal rodents is difficult due to their dependency on the mother, but the relatively independent piglet is increasingly identified as a valuable translational model for humans. This study was designed to correlate immune regulation in piglets with early-life environment. Methods: Piglets were nursed by their mother on a commercial farm, while isolator-reared siblings were formula fed. Fluorescence immunohistology was used to quantify T-reg and effector T-cell populations in the intestinal lamina propria and the systemic response to food proteins was quantified by capture ELISA. Results: There was more CD4+ and CD4+CD25+ effector T-cell staining in the intestinal mucosa of the isolator-reared piglets compared with their farm-reared counterparts. In contrast, these isolator-reared piglets had a significantly reduced CD4+CD25+Foxp3+ regulatory T-cell population compared to farm-reared littermates, resulting in a significantly higher T-reg-to-effector ratio in the farm animals. Consistent with these findings, isolator-reared piglets had an increased serum IgG anti-soya response to novel dietary soya protein relative to farm-reared piglets. Conclusion: Here, we provide the first direct evidence, derived from intervention, that components of the early-life environment present on farms profoundly affects both local development of regulatory components of the mucosal immune system and immune responses to food proteins at weaning. We propose that neonatal piglets provide a tractable model which allows maternal and treatment effects to be statistically separated.
