Kew S, Wells S M, Yaqoob P, Wallace F A, Miles E A, Calder P C
Institute of Human Nutrition, University of Southampton, Bassett Crescent East, Southampton SO16 7PX, United Kingdom.
J Nutr. 1999 Aug;129(8):1524-31. doi: 10.1093/jn/129.8.1524.
To examine the effects of dietary glutamine on lymphocyte function, male mice aged 6 wk were fed for 2 wk one of three isonitrogenous, isocaloric diets, which varied in glutamine concentration. The control diet included 200 g casein/kg, providing 19.6 g glutamine/kg; the glutamine-enriched diet provided 54.8 g glutamine/kg partly at the expense of casein; and the alanine + glycine-enriched diet provided 13.3 g glutamine/kg. The plasma concentrations of a number of amino acids varied because of the diet fed. The plasma glycine concentration was greater in mice fed the alanine + glycine-enriched diet (380 +/- 22 micromol/L) than in mice fed the control (177 +/- 17 micromol/L) or the glutamine-enriched (115 +/- 18 micromol/L) diets. The plasma glutamine concentration was greater in mice fed the glutamine-enriched diet (945 +/- 117 micromol/L) than in those fed the diet enriched with alanine + glycine (561 +/- 127 micromol/L), but was not different from that in mice fed the control diet (791 +/- 35 micromol/L). There was a significant linear relationship between the amount of glutamine in the diet and plasma glutamine concentration (r = 0.655, P = 0.015). Plasma alanine concentration was unaffected by diet. The reason for the lack of effect of increasing the amount of alanine in the diet upon its concentration in the circulation may relate to its use by the liver. Thymidine incorporation (56 +/- 18 kBq/well versus <10 kBq/well), expression of the alpha-subunit of the interleukin-2 receptor (62 versus 30% receptor positive cells) and interleukin-2 production [189 +/- 28 versus 106 +/- 5 (control) or 61 +/- 13 (alanine + glycine enriched) ng/L] were greater for concanavalin A-stimulated spleen lymphocytes from mice fed the glutamine-enriched diet compared to those from mice fed the other two diets. Thus, increasing the amount of glutamine in the murine diet enhances the ability of T lymphocytes to respond to mitogenic stimulation. Taken together, these observations suggest that increasing the oral availability of glutamine could promote the T-cell driven, cell-mediated immune response.
为研究膳食谷氨酰胺对淋巴细胞功能的影响，选用6周龄雄性小鼠，分别给予三种等氮、等热量但谷氨酰胺浓度不同的饲料，喂养2周。对照饲料含200 g酪蛋白/kg，提供19.6 g谷氨酰胺/kg；谷氨酰胺强化饲料提供54.8 g谷氨酰胺/kg，部分替代酪蛋白；丙氨酸+甘氨酸强化饲料提供13.3 g谷氨酰胺/kg。因喂养的饲料不同，多种氨基酸的血浆浓度有所变化。喂食丙氨酸+甘氨酸强化饲料的小鼠血浆甘氨酸浓度（380±22 μmol/L）高于喂食对照饲料（177±17 μmol/L）或谷氨酰胺强化饲料（115±18 μmol/L）的小鼠。喂食谷氨酰胺强化饲料的小鼠血浆谷氨酰胺浓度（945±117 μmol/L）高于喂食丙氨酸+甘氨酸强化饲料的小鼠（561±127 μmol/L），但与喂食对照饲料的小鼠（791±35 μmol/L）无差异。饲料中谷氨酰胺含量与血浆谷氨酰胺浓度呈显著线性关系（r = 0.655，P = 0.015）。血浆丙氨酸浓度不受饲料影响。饲料中丙氨酸含量增加而其循环浓度未受影响，原因可能与肝脏对丙氨酸的利用有关。与喂食其他两种饲料的小鼠相比，喂食谷氨酰胺强化饲料的小鼠经刀豆蛋白A刺激的脾淋巴细胞的胸苷掺入量（56±18 kBq/孔对<10 kBq/孔）、白细胞介素-2受体α亚基的表达（62%对30%受体阳性细胞）和白细胞介素-2产生量[189±28对106±5（对照）或61±13（丙氨酸+甘氨酸强化）ng/L]更高。因此，增加小鼠饲料中谷氨酰胺的含量可增强T淋巴细胞对有丝分裂原刺激的反应能力。综上所述，这些观察结果表明，增加谷氨酰胺的口服摄入量可促进T细胞驱动的细胞介导免疫反应。
