Vitamin A Deficiency Decreases Natural Killer Cell Activity and Interferon Production in Rats

Abstract

We examined the effect of vitamin A deficiency on natural killer (NK) cell activity and interferon (IFN) production. Rats were weaned at 16 or 21 d of age onto semisynthetic diets containing either 0 or 4 micrograms retinol/g diet. At the time of study, retinol-depleted rats had serum vitamin A concentrations less than 7% of those of pair-fed controls. In two studies, rats exhibited no external signs of retinol deficiency, but with further depletion some symptoms were observed. Splenic NK cell activity against chromium-51-labeled YAC-1 cells was significantly decreased in vitamin A-depleted rats (22-80% of values for control rats, depending on the degree of retinol deficiency), regardless of the ratio of effector to target cells used. When vitamin A-depleted rats were repleted orally with retinol, NK cell activity was consistently normalized. To understand the possible mechanisms involved in decreasing NK cell activity, we investigated IFN production by concanavalin A-stimulated spleen cells from vitamin A-depleted, from repleted and from control animals. IFN titers were significantly decreased (22-33% of values for control rats) in supernatants of spleen cell cultures of the vitamin A-depleted rats. Repletion with vitamin A resulted in IFN activities ranging from 80 to 130% of controls. Adding alpha/beta IFN in vitro to the spleen cells of vitamin A-depleted animals increased their NK cell activity. The number of spleen cells reacting with a monoclonal antibody specific for rat NK cells was slightly lower in retinol-depleted rats, but not enough to account for the differences in NK cell and IFN activities. These data suggest that vitamin A deficiency affect the nonspecific arm of the immune system, possibly by altering the functional capacity of cells to produce lymphokines needed for the generation of an appropriate cytolytic response.

Reduced production of immunoregulatory cytokines in vitamin A- and zinc-deficient Indonesian infants

“…Studies in animals have given conflicting results however. Depression of T-cell activation is reported, supported by findings of decreased interferon-g (IFN-g) production and decreased natural killer (NK) cell activity (Bowman et al, 1990;Ross & Stephensen, 1996). Other studies report however overproduction of IFN-g and reduced antibody production, fitting with a Th1 predominance (Wiedermann et al, 1993;Cantorna et al, 1994).…”

Sobrevida e processos infecciosos em pacientes com AIDS: análise de acordo com os níveis séricos iniciais de vitamina A

“…No entanto, ao analisarmos a sobrevida média global no período do estudo (36 meses) não verificamos diferenças significativas entre os dois grupos. Uma das possíveis explicacões para este último fato poderia ter sido a inclusão de um número considerável de pacientes já em estado avançado da AIDS, uma vez que a mediana da contagem de linfócitos CD 4 + no início do acompanhamento foi bastante baixa, menor que 50 células/mm 3 .…”

“…Relato utilizando modelo de AIDS murina, demonstrou evolução desfavorável da doença nos animais alimentados com dieta deficiente em vitamina A 28 . Semba et al 19 , estudando pacientes norteamericanos com AIDS, verificaram haver associação de deficiência de vitamina A, baixos valores de linfócitos CD 4 + e maior taxa de mortalidade. Por outro lado, Tang et al 25 , estudando uma população de pacientes com AIDS e níveis normais de vitamina A, não observaram relação entre os níveis séricos de retinol e a progressão da doença.…”

“…Na região de Ribeirão Preto, SP, Brasil, Silveira 20 encontrou níveis séricos abaixo de 1,6µmol/L em 51,1% dos 45 pacientes avaliados. Neste trabalho, não houve correlação dos níveis de retinol com o estado nutricional global dos pacientes e nem com os valores de linfócitos CD 4 + /mm 3 , ao contrário do verificado por Semba 18 .…”

Relationship between Immune Function and Serum Vitamin A in Japanese Black Beef Cattle

“…Serum samples collected by tubes with no anticoagulant were used to measure the serum total cholesterol (TC; enzyme assay), γ-glutamyl transpeptitase (GGT; enzyme assay) and blood urea nitrogen (BUN; urease indophenol method). The serum VA concentration was measured by high performance liquid chromatography [7]. White blood cell counts (WBC) were determined with a blood cell counter (PC607, ERMA, Germany).…”