Cummins A G, Thompson F M, Mayrhofer G
Gastroenterology Unit, Queen Elizabeth Hospital, Woodville, South Australia.
J Pediatr Gastroenterol Nutr. 1991 Apr;12(3):361-8. doi: 10.1097/00005176-199104000-00013.
Activation of the mucosal immune system peaks at weaning on days 21 and 22 of life in the rat. We have investigated activation in the gut associated lymphoid tissue and maturation of intestinal mucosa in hypothymic (nude) and in phenotypically normal heterozygous CBH rats at 22 days of life. Intestinal maturation, as assessed by villus area, crypt length, crypt cell production rate and disaccharidase activity, was similar in hypothymic and normal rats, and indices of mucosal immune function were elevated in both groups at this time. The proportion of mononuclear cells from the mesenteric lymph node expressing IL-2R was 11% in heterozygous and 14% in hypothymic rats as determined by flow cytometry. Immunoperoxidase staining of MLN sections confirmed the presence of IL-2R+ cells in the T-dependent interfollicular areas. However, the number of T-cells was considerably depleted in hypothymic rats. Intraepithelial lymphocyte counts and serum rat mucosal mast cell protease II concentrations were similar in the two groups, while counts of jejunal mucosal mast cells and eosinophils were paradoxically increased in hypothymic animals. As T lymphocyte function is thought to be impaired in hypothymic rats, the intact mucosal immune activity in hypothymic rats could be due to activation of intrinsic "thymic independent" T lymphocytes in hypothymic rats, or to engraftment with extrinsic maternal milk-derived lymphocytes and their activation in the infant rat gut.
大鼠在出生后第21天和22天断奶时，黏膜免疫系统的激活达到峰值。我们研究了出生22天的无胸腺（裸）大鼠和表型正常的杂合CBH大鼠肠道相关淋巴组织的激活情况以及肠黏膜的成熟情况。通过绒毛面积、隐窝长度、隐窝细胞产生率和双糖酶活性评估的肠道成熟情况，在无胸腺大鼠和正常大鼠中相似，此时两组的黏膜免疫功能指标均升高。通过流式细胞术测定，杂合大鼠肠系膜淋巴结中表达IL-2R的单核细胞比例为11%，无胸腺大鼠为14%。MLN切片的免疫过氧化物酶染色证实了在T细胞依赖的滤泡间区域存在IL-2R+细胞。然而，无胸腺大鼠中的T细胞数量明显减少。两组的上皮内淋巴细胞计数和血清大鼠黏膜肥大细胞蛋白酶II浓度相似，而无胸腺动物空肠黏膜肥大细胞和嗜酸性粒细胞的计数却反常增加。由于无胸腺大鼠的T淋巴细胞功能被认为受损，无胸腺大鼠完整的黏膜免疫活性可能是由于无胸腺大鼠体内固有“胸腺非依赖性”T淋巴细胞的激活，或者是由于外来母源乳源性淋巴细胞的植入及其在幼鼠肠道中的激活。
