Carver J D
Department of Pediatrics, University of South Florida College of Medicine, Tampa 33606.
J Nutr. 1994 Jan;124(1 Suppl):144S-148S. doi: 10.1093/jn/124.suppl_1.144S.
Investigations with animals demonstrate that dietary nucleotides influence immune function. Restriction of dietary nucleotides in mice decreases several indices of cell-mediated immunity as well as resistance to challenge with Staphylococcus aureus or Candida albicans. Spleen cells of mice maintained on nucleotide-free diet produce less interleukin-2 and have lower natural killer cell cytotoxicity and macrophage activation than those of animals fed nucleotide-supplemented diets. In vivo lymphoproliferative response, macrophage phagocytic activity and expression of interleukin-2 receptor and lyt1 surface marker are also lower in animals fed nucleotide-free diets. At 2 mo of age, infants fed breast milk or nucleotide-supplemented infant formula exhibit increased natural killer cell activity compared with infants fed unsupplemented formula. Dietary nucleotide restriction in animals may also result in hepatic lipid accumulation and decreased mucosal height and gut wall thickness. Adenosine monophosphate, a mediator of hepatic and small bowel blood flow, may play a unique role among the nucleotides studied. In conclusion, de novo synthesis and salvage of nucleotides is a metabolically costly process. An exogenous source of nucleotides from the diet may optimize the function of rapidly dividing tissues, particularly when growth is rapid and the diet is low in nucleotides.
对动物的研究表明，膳食核苷酸会影响免疫功能。限制小鼠的膳食核苷酸会降低细胞介导免疫的多项指标，以及对金黄色葡萄球菌或白色念珠菌攻击的抵抗力。与喂食补充核苷酸饮食的动物相比，维持无核苷酸饮食的小鼠的脾细胞产生的白细胞介素-2更少，自然杀伤细胞的细胞毒性和巨噬细胞活性更低。在无核苷酸饮食喂养的动物中，体内淋巴细胞增殖反应、巨噬细胞吞噬活性以及白细胞介素-2受体和lyt1表面标志物的表达也较低。在2月龄时，与喂食未添加核苷酸配方奶粉的婴儿相比，喂食母乳或添加核苷酸婴儿配方奶粉的婴儿自然杀伤细胞活性增加。动物膳食核苷酸限制也可能导致肝脏脂质积累以及黏膜高度降低和肠壁厚度减小。在研究的核苷酸中，一磷酸腺苷作为肝脏和小肠血流的介质可能发挥独特作用。总之，核苷酸的从头合成和补救是一个代谢成本高昂的过程。来自饮食的外源性核苷酸来源可能会优化快速分裂组织的功能，特别是在生长迅速且饮食中核苷酸含量较低时。
