Ahmad Shaikh M, Haskell Marjorie J, Raqib Rubhana, Stephensen Charles B
Program in International and Community Nutrition, Department of Nutrition, University of California Davis, CA 95616, USA.
J Nutr. 2008 Nov;138(11):2276-83. doi: 10.3945/jn.108.092056.
Current recommendations for vitamin A intake and liver stores (0.07 micromol/g) are based on maintaining normal vision. Higher levels may be required for maintaining normal immune function. The objective of this study was to assess the relationship between total body vitamin A stores in adult men and measures of adaptive immune function. We conducted an 8-wk residential study among 36 healthy Bangladeshi men with low vitamin A stores. Subjects received a standard diet and were randomized in a double-blind fashion to receive vitamin A (240 mg) or placebo during wk 2 and 3. Subjects received Yellow Fever Virus (YFV) and tetanus toxoid (TT) vaccines during wk 5. Vitamin A stores were estimated by isotopic dilution during wk 8. Vaccine-specific lymphocyte proliferation, cytokine production, and serum antibody responses were evaluated before and after vaccination. Vitamin A supplementation increased YFV- and TT-specific lymphocyte proliferation and YFV-specific interleukin (IL)-5, IL-10, and tumor necrosis factor-alpha production but inhibited development of a TT-specific IL-10 response. Both groups developed protective antibody responses to both vaccines. Some responses correlated positively with vitamin A stores. These findings indicate that the currently recommended vitamin A intake is sufficient to sustain a protective response to YFV and TT vaccination. However, YFV-specific lymphocyte proliferation, some cytokine responses, and neutralizing antibody were positively associated with liver vitamin A stores > 0.084 micromol/g. Such increases may enhance vaccine protection but raise the question of whether immune-mediated chronic diseases may by exacerbated by high-level dietary vitamin A.
目前关于维生素A摄入量和肝脏储存量（0.07微摩尔/克）的建议是基于维持正常视力。维持正常免疫功能可能需要更高的水平。本研究的目的是评估成年男性体内维生素A总储存量与适应性免疫功能指标之间的关系。我们对36名维生素A储存量低的健康孟加拉男性进行了一项为期8周的居住研究。受试者接受标准饮食，并在第2周和第3周以双盲方式随机接受维生素A（240毫克）或安慰剂。受试者在第5周接种黄热病病毒（YFV）和破伤风类毒素（TT）疫苗。在第8周通过同位素稀释法估计维生素A储存量。在接种疫苗前后评估疫苗特异性淋巴细胞增殖、细胞因子产生和血清抗体反应。补充维生素A可增加YFV和TT特异性淋巴细胞增殖以及YFV特异性白细胞介素（IL）-5、IL-10和肿瘤坏死因子-α的产生，但抑制TT特异性IL-10反应的发展。两组对两种疫苗均产生了保护性抗体反应。一些反应与维生素A储存量呈正相关。这些发现表明，目前推荐的维生素A摄入量足以维持对YFV和TT疫苗接种的保护性反应。然而，YFV特异性淋巴细胞增殖、一些细胞因子反应和中和抗体与肝脏维生素A储存量>0.084微摩尔/克呈正相关。这种增加可能会增强疫苗保护作用，但也引发了一个问题，即高水平饮食中的维生素A是否会加剧免疫介导的慢性疾病。
