VITAMIN-A AND RETINOIDS IN ANTIVIRAL RESPONSES

Vitamin A deficiency results in multiple derangements that impair the response to infection, This review focuses on experimental models of s pecific virus infections and on cytokines and cells with cytolytic act ivity important to antiviral defenses, Altered specific antibody respo nses and greater epithelial damage in vitamin A-deficient hosts are co nsistent findings, The cytolytic activity of natural killer cells and various cytokine responses are altered, The inflammatory response to i nfection may also result in derangements in the transport and metaboli sm of retinol, We speculate that interaction of several factors may co mbine to explain the greater severity of infection seen in vitamin A-d eficient animals and children, In addition to a preexisting lack of ti ssue vitamin A, these factors may include reduced mobilization and inc reased excretion of retinol during the acute phase response to infecti on, poor innate and specific immune response to virus, and delayed rep air of damaged epithelia. Foci of vitamin A-deficient epithelia may be sites of penetration of bacteria and other agents, leading to seconda ry infections and contributing to an increased severity of infections and poor outcome in vitamin A-deficient animals and humans.