A comparison of the effect of vitamin A on cytokine secretion by mononuclear cells of preterm newborns and adults

Background: For a long time vitamin A has been known to be essential for immune defense of the organism and protection against infections. Vitamin A deficiency in children is associated with morbidity and mortality from infectious diseases which could be prevented and even alleviated by vitamin A supplementation. Moreover, this vitamin is involved in the modulation of immunological and inflammatory responses by regulation of cytokine production. The aim of the study was to compare the in vitro effect of vitamin A on the production of pro-inflammatory (IL-1β and IL-6) and anti-inflammatory (IL-1 receptor antagonist (ra) and IL-10) cytokines, as well as IL-2 and IFNγ by cord blood mononuclear cells (CBMC) of preterm newborns to that of peripheral blood mononuclear cells (PBMC) from adults. Methods: Mononuclear cells (MC) from individuals of the two age groups were incubated with vitamin A (retinyl palmitate) at various concentrations in the presence of phytohemagglutinin for IL-2 and IFNγ production or LPS for IL-1β, IL-1ra, IL-6 and IL-10 secretion. The level of the cytokines in the supernatants was tested by ELISA. Results: Vitamin A exerted an in vitro inhibitory effect on the production of the anti-inflammatory cytokine IL-1ra by MC of preterm newborns and adults, but did not affect the secretion of the pro-inflammatory cytokines IL-1β, IL-6 and IFNγ. Vitamin A caused inhibition of IL-10 secretion by cells from adults, but it did not significantly affect this function in cells from newborns except when high unphysiological doses were applied. In addition vitamin A stimulated the secretion of IL-2 by cells isolated from adults but had no effect on those derived from premature neonates. Conclusions: The results indicate that vitamin A may affect the immune function of premature infants via inhibition of IL-1ra secretion. It is suggested that the beneficial effect of vitamin A on the clinical course of bronchopulmonary dysplasia (BPD) may be due to the reduced production of anti-inflammatory cytokines by neonatal CBMC. This may indicate the importance of the pro-inflammatory cytokines in the management of severe lung diseases and BPD.