The function of neutrophils appears to be impaired during vitamin A deficiency. Neutrophils play an important role in non-specific immunity, because they phagocytose and kill bacteria, parasites, virus-infected cells and tumour cells. Retinoic acid plays an important role in the normal maturation of neu-trophils (Lawson and Berliner, 1999). Vitamin A-deficient rats had widespread defects in neutrophil function, including impaired chemotaxis, adhesion, phagocytosis and ability to generate active oxidant molecules, compared with neutrophils from controls (Twining et al., 1996). In rats challenged with Staphylococcus aureus, impaired phagocytosis and decreased complement lysis activity were found in vitamin A-deficient rats compared with control rats (Wiedermann et al., 1996). Vitamin A treatment was shown to increase superoxide production by neutrophils from Holstein calves (Higuchi and Nagahata, 2000).

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