胃肠道不但是人体的一个消化和吸收器官,也是一个重要免疫器官。吞咽到消化道腔里物质包括微生物和其他具有抗原性物质的化合物,该物质在胃肠腔内受到免疫作用,而除去有害性。因为肠道具有丰富的淋巴组织,大量淋巴细胞,浆细胞对来自肠道有害物质——细菌、病毒、原虫、食物毒素等,产生体液免疫和细胞免疫反应,即组成消化系的第一线免疫和防御系统(粘膜免疫系统)。而肝脏中的星状细胞和血窦内的吞噬细胞及脾脏产生的抗体,调理素及补体,进一步消灭穿过第一道防御系统而进入机体的抗原性物质,而组成消化系第二线免疫防御系统。故称消化系中肠—肝—脾是一个免疫整体。婴儿在出生头几天至8周,吞咽母乳所含的抗 The gastrointestinal tract is not only a digestive and absorption organ of the body, but also an important immune organ. Swallowing into the digestive tract cavity substances include microorganisms and other compounds that have antigenic substances that are immunized in the gastrointestinal tract to remove the noxiousness. Because the intestine is rich in lymphoid tissue, a large number of lymphocytes, plasma cells on the intestinal tract from harmful substances - bacteria, viruses, protozoa, food toxins, resulting in humoral and cellular immune responses, that constitute the first line of immunization of the digestive system And defense system (mucosal immune system). The stellate cells in the liver and the phagocytes and spleens in the sinusoids produce opsonin and complement, further eliminating the antigenic substances that enter the body through the first defense system and form the second line of immune defense system. Therefore, the digestive system in the intestine - liver - spleen is an immune whole. Infants in the first few days to eight weeks of birth, swallowing the anti-breast milk