Developmentally regulated gene expression of Th2 cytokines in the brain

Given the critical role of cytokines in the regulation of an inflammatory r esponse, we investigated whether certain cytokines are expressed in the bra ins of normal mice during maturation that could contribute to the immune-pr ivileged nature of the CNS or potentially influence an immune-mediated illn ess such as experimental allergic encephalomyelitis. The gene expression of IFN gamma (Th1 cytokine) and IL-4 (Th2 cytokine) was analyzed in the brain of several strains of mice. IFN gamma was not detectable. However, IL-4 wa s present in the brains of neonatal mice, but not adult mice. Resident CNS cells are believed to be the source of the IL-4, because mice deficient in T cells (SCID and RAG2-/-) expressed the IL-4 gene in the CNS. Further anal ysis indicated that the gene expression of the Th2 cytokine transcription f actor, GATA-3, correlated with IL-4 and IL-10 expression in the brain. Sinc e GATA-3-deficient mice have an abnormal CNS, brain-derived Th2 cytokines m ay play an important role in CNS development, as well as potentially contri bute to the immune-privileged nature of the brain. (C) 2000 Elsevier Scienc e B.V. All rights reserved.