| Vitamin A is a necessary micronutrient for human body .There are many active derivatives of vitamin A including retinol ,retinoic acid , and the relationship of vitamin A and immunity is close .With the development of study ,people gradually realize that vitamin A can influence both cell immunity and humoral immunity .Vitamin A can maintain the integrity of mucous membrane ,facilitate the excretion of mucus ,decrease squamous metaplasia of mucosal epithelia and accelerate the excretion of sIgA and the development of spleen and thymus .Vitamin A can increase the function of neutrophil ,NK cell ,macrophage cell and DC .Vitamin A can accelerate the growth ,differentiation and maturation of T cell and B cell .Recently many studies indicate that vitamin A can influnence the net of cytokines especially the balance of Th1 cell and Th2 cell .The balance of Th1 cell and Th2 cell is the most important keypoint of immunemodulation There are more and more studies about the relationship between the balance of Th1 cell and Th2 cell and the diseases .People think that the mechnism of diseases can be divided into two groups such as Th1 cell predominance, and Th2 cell predominance .It has been reported that Vitamin A deficiency (VAD) can inhibits the Th2 cell immune response overseas .But there is few study that vitamin A influence the balance of Th1 cell and Th2 cell immune responses inland ..VAD occurs easily in children .So WHO point out that VAD is the main nutrient problem of children in the developing countries. The supplement of vitamin A has been advocated in children. The function of vitamin A is so important and the recognition is limited . Vitamin A is recognized as a nutrient that can increase the immunity of body . Supplement of vitamin A can been seen in children and in the clinical .The supplement of vitamin A can decrease the mortality of measles and diarrhea ,but it can influence pneumonia mortality hardly.To observe the influence of vitamin A on the balance of Th1 cell and Th2 cell immune responses and provide the theory for the supplement of vitamin A in children .In this study ,we raised the mice for five weeks by three different interventions :(1)a high level vitamin A (25000IU/Kg diet) (2)control group (4000IU/Kg diet) (3)a low level vitamin A (basic diet containing no vitamin A).Then we measured the concentration of vitamin A in serum and the cytokines in the CD4+ T cell including IFN-γ and IL-4 .No difference was seen among the interventions in body weight of mice. However there were significant differences between three interventions in serum vitamin A concentration .The production of interferon-gamma (IFN-γ), a Th1 cytokine ,was lower in the high level diet group (median10.37±2.04) and higher in the low level group (median,28.60±10.82)compared with the control group (median 20.13±6.39)P<0.01,whereas the production of interleukin-4 (IL-4),a Th2 cytokine ,was higher in the high level diet (median 5.31±2.04)and lower in the low level diet group (median ,1.26±0.87)compared with the control(median 2.80±1.37)P<0.01.The ratio of IFN-γ/IL-4 was higher in the low level diet group (median ,32.01± 17.50) and lower in the high level diet group (median ,2.17±0.70) compared with the control group (median ,7.91±2.10) . IFN-γ is produced by T cell , NK cell and macrophage cell. IFN-γ can induce the Th0 cell to Th1 cell , improve the ability to anti-virus ,and inhibit the activity of B cell and the production of IgE induced by IL-4 .IL-4 is produced by T cell .IL-4 can accelerate the proliferation and differentiation of B cell ,induce the Th0 cell to Th2 cell ,facilitate the production of IgE and inhibit the production and function of IFN-γ .Th1 cell and Th2 cell all derive from Th0 cell .Th1 cell excretes many kinds of cytokines including IL-2,IL-12, IFN-γ, TNF-α and IFN-γ can represents the level of Th1.Th2 cell excretes many kinds of cytokines including IL-4,IL-5,Il-6,IL-10,IL-13 and IL-4 can represents the level of Th2.The ratio of IFN-γ/IL-4 can represents the balance of Th1 cell a... |
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