婴儿早期肠道中如果繁殖有大量的大肠杆菌，则婴儿机体的血液中将会有较多数量的记忆B细胞，近日，来自瑞典歌德堡大学的研究者这样表示。相关研究成果刊登在了国际杂志The Journal of Immunology上。
我们肠道中的细菌远远超过我们机体中的细胞数量，而且这些细菌对于机体的健康至关重要，因为细菌可以刺激人类机体的免疫系统成熟。一般情况下，正常的肠道细菌菌群是在我们人类生命初期开始建立的，但是近年来人类增加的卫生生活方式改变了细菌菌群。
目前来讲，大肠杆菌在瑞典的儿童的肠道中寄居时间越来越晚，而且在肠道中开始存在少量各种各样的不同的细菌，于此同时，因为免疫调节缺失所引起的疾病不断增加，使得变态反应成为西方国家一个主要的公众健康问题。
B细胞在变态反应发展的过程中扮演者重要角色
B细胞是一种白细胞，可以通过产生抗体来保护机体免受感染以及在变态反应的发展过程中起到了关键的作用。研究者们通过对B细胞进行相关研究，以及Vastra Gotaland地区65个健康新生儿的相关研究，表明在出生一周的婴儿肠道内如果有大肠杆菌寄居的话，在婴儿成长至4个月和18个月的时候，其体内的记忆B细胞数量会大量增加。这样的结果对于我们理解肠道细菌菌群和免疫系统发展之间的关系至关重要，而且提醒我们过度卫生生活方式多带来的健康风险。
研究者表示，人类周围的的大部分细菌都是无害的，我们应该视它们为锻炼我们机体免疫力的一种锻炼方式，一遍我们的免疫系统可以成熟地更加完全，健康的新生儿并不需要过度保护而使其不与细菌接触。（生物谷：T.Shen<微博>编译）
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doi:10.4049/jimmunol.1103223
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Infant B Cell Memory Differentiation and Early Gut Bacterial Colonization
Anna-Carin Lundell*, Viktor Björnsson*, Annika Ljung†, Margareta Ceder‡, Susanne Johansen§, Gunhild Lindhagen¶, Carl-Johan Törnhage‖, Ingegerd Adlerberth†, Agnes E. Wold† and Anna Rudin*
Germ-free animal models have demonstrated that commensal bacterial colonization of the intestine induces B cell differentiation and activation. Whether colonization with particular bacterial species or groups is associated with B cell development during early childhood is not known. In a prospective newborn/infant cohort including 65 Swedish children, we examined the numbers and proportions of CD20+, CD5+, and CD27+ B cells in blood samples obtained at several time points during the first 3 y of life using flow cytometry. Fecal samples were collected and cultured quantitatively for major facultative and anaerobic bacteria at 1, 2, 4, and 8 wk of life. We found that the numbers of CD20+ B cells and CD5+CD20+ B cells reached their highest levels at 4 mo, whereas CD20+ B cells expressing the memory marker CD27 were most numerous at 18 and 36 mo of age. Using multivariate analysis, we show that early colonization with Escherichia coli and bifidobacteria were associated with higher numbers of CD20+ B cells that expressed the memory marker CD27 at 4 and 18 mo of age. In contrast, we were unable to demonstrate any relation between bacterial colonization pattern and numbers of CD20+ or CD5+CD20+ B cells. These results suggest that the intestinal bacterial colonization pattern may affect the B cell maturation also in humans, and that an early gut microbiota including E. coli and bifidobacteria might promote this maturation.
