Vitamin A and retinoic acid in T cell-related immunity

Department of Nutritional Sciences, Pennsylvania State University, University Park, PA.
American Journal of Clinical Nutrition (Impact Factor: 6.77). 10/2012; 96(5):1166S-72S. DOI: 10.3945/ajcn.112.034637
Source: PubMed


Interest in vitamin A as a regulator of immune function goes back to the early 1900s. Recently, several lines of evidence have converged to show that retinoic acid (RA), a major oxidative metabolite of vitamin A, plays a key role in the differentiation of T cell subsets, the migration of T cells into tissues, and the proper development of T cell-dependent antibody responses. This review discusses evidence from experimental studies that RA promotes the differentiation of regulatory T cells, which help to suppress inflammatory reactions, and plays a significant role in normal mucosal immunity by modulating T cell activation and regulating cell trafficking. RA also promotes antibody responses to T cell-dependent antigens. Conversely, in a state of vitamin A deficiency, inflammatory T cell reactions may be inadequately opposed and therefore become dominant. Although data from human studies are still needed, the framework now developed from studies in mice and rat models suggests that adequate vitamin A status, whether derived from ingestion of preformed retinol or β-carotene, is important for maintaining a proper balance of well-regulated T cell functions and for preventing excessive or prolonged inflammatory reactions.

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    • "Its deficiency is associated with squamous metaplasia of the conjunctiva (Mckelvie, 2003). Vitamin A also acts as a mucosal and systemic immune enhancer through immunohomeostasis of CD4þ helper T cells and Treg cells (Hall et al., 2011; Pino-Lagos et al., 2011; Ross, 2012). These cells are part of tumour immuno-surveillance. "
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    • "Vitamin A also promotes antibody responses to T-cell–dependent antigens [38] and increases protective antitumor immunity through mechanisms such as induction of cell differentiation and enhancement of migration to lymph nodes [39]. "
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    • "Potential benefits are highlighted by GM rice strains modified to produce high levels of beta-carotene. Vitamin A deficiency severely impairs immune function and thus any alleviation could produce dramatic benefit in parts of the world with both low nutrient supply and high exposure to pathogens [200]. While not without vocal detractors [201], use of GM rice is equivalent to supplement pills at providing adequate intake of vitamin A in children and thus offers a potentially life-saving benefit, as delivering beta-carotene through rice would be easier and more economically sustainable than through medication [202]. "
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