Bounous G, Batist G, Gold P
Montreal General Hospital, Quebec.
Clin Invest Med. 1989 Jun;12(3):154-61.
The spleen cells immune response to sheep red blood cells of C3H/HeJ mice fed a 20 g whey protein/100 g diet is substantially higher than that of mice fed an equivalent casein diet of similar nutritional efficiency. The present study indicates that the observed immunoenhancing effect of the whey protein mixture is dependent on the overall amino acid pattern resulting from the contribution of all its protein components. Whey protein contains substantially more cysteine than casein. Dietary cysteine is considered to be a rate limiting substrate for the synthesis of glutathione which is necessary for lymphocyte proliferation. Our studies show that enhancement of host humoral immune response is associated with greater and more sustained production of splenic glutathione during the antigen driven clonal expansion of the lymphocyte in whey protein fed mice in comparison to mice fed the equivalent casein or the cysteine-enriched casein diet. Hence the efficiency of dietary cysteine in inducing supernormal glutathione levels is greater when it is delivered in the whey protein than as free cysteine. Administration of S-(n-butyl) homocysteine sulfoximine, which reduces splenic glutathione level by half, produces a 4-5 fold drop in the humoral immune response of whey protein diet-fed mice. This is further evidence of the important role of glutathione in the immunoenhancing effect of dietary whey protein.
喂食含20克乳清蛋白/100克日粮的C3H/HeJ小鼠的脾细胞对绵羊红细胞的免疫反应显著高于喂食具有相似营养效率的等量酪蛋白日粮的小鼠。本研究表明，观察到的乳清蛋白混合物的免疫增强作用取决于其所有蛋白质成分贡献所产生的整体氨基酸模式。乳清蛋白含有的半胱氨酸比酪蛋白多得多。膳食半胱氨酸被认为是合成淋巴细胞增殖所必需的谷胱甘肽的限速底物。我们的研究表明，与喂食等量酪蛋白或富含半胱氨酸的酪蛋白日粮的小鼠相比，在喂食乳清蛋白的小鼠中，在抗原驱动的淋巴细胞克隆扩增过程中，宿主体液免疫反应的增强与脾脏谷胱甘肽的更多且更持续的产生有关。因此，当半胱氨酸以乳清蛋白形式提供时，其诱导超正常谷胱甘肽水平的效率比以游离半胱氨酸形式提供时更高。给予S-（正丁基）高半胱氨酸亚砜亚胺可使脾脏谷胱甘肽水平降低一半，这会使喂食乳清蛋白日粮的小鼠的体液免疫反应下降4至5倍。这进一步证明了谷胱甘肽在膳食乳清蛋白免疫增强作用中的重要作用。
