Bruce M G, Strobel S, Hanson D G, Ferguson A
Gastro-Intestinal Unit, University of Edinburgh, UK.
Clin Exp Immunol. 1987 Dec;70(3):611-8.
'Intestinal antigen processing' is a function of the gastro-intestinal tract whereby shortly after an animal has been fed an immunogenic protein antigen, such as ovalbumin (OVA), a tolerogenic form of the protein is generated and can be detected in the circulation. The effect of damage to the intestinal epithelium on the processing of OVA has been examined in lethally irradiated mice. Irradiated animals were fed 25 mg OVA and their serum collected 1 h later. When this serum was transferred intraperitoneally into naive recipient mice, this did not induce the typical suppression of systemic delayed-type hypersensitivity. Results were similar when the serum donors were at 2 days after irradiation, with crypt hypoplasia, and at 5 days after irradiation when there was reactive crypt hyperplasia. However reconstitution of donors with normal spleen cells immediately after irradiation restored their capacity to generate a tolerogenic form of the antigen. Immunoreactive OVA was detected by ELISA in both tolerizing and non-tolerizing sera, and the immunological properties of these sera were not related to serum levels of OVA after feeding. Thus subtle immunochemical alterations in the nature of a protein antigen are likely to be more important than the quantity of absorbed antigen, in influencing systemic cell-mediated immune responses after feeding. The lack of generation of a tolerogenic form of the protein in irradiated mice, unrelated to the pattern of epithelial cell kinetics, and the restoration of this function by normal spleen cells, suggests that lymphoid cells may be involved in the phenomenon of antigen processing.
“肠道抗原加工”是胃肠道的一项功能，即动物摄入免疫原性蛋白抗原（如卵清蛋白，OVA）后不久，会产生该蛋白的一种致耐受性形式，并可在循环中检测到。在接受致死剂量照射的小鼠中，研究了肠道上皮损伤对OVA加工的影响。给受照射动物喂食25mg OVA，并在1小时后收集它们的血清。当将这种血清腹腔注射到未接触过抗原的受体小鼠体内时，并未诱导出典型的全身性迟发型超敏反应抑制。当血清供体处于照射后2天（隐窝发育不全）以及照射后5天（隐窝反应性增生）时，结果相似。然而，照射后立即用正常脾细胞重建供体，可恢复其产生抗原致耐受性形式的能力。通过ELISA在致耐受性血清和非致耐受性血清中均检测到了免疫反应性OVA，并且这些血清的免疫特性与喂食后血清中的OVA水平无关。因此，在影响喂食后全身性细胞介导的免疫反应方面，蛋白质抗原性质的细微免疫化学改变可能比吸收抗原的量更为重要。照射小鼠中缺乏蛋白质致耐受性形式的产生，这与上皮细胞动力学模式无关，而正常脾细胞可恢复此功能，这表明淋巴细胞可能参与了抗原加工现象。
