Interleukin-4 down-regulates adult human astrocyte DNA synthesis and proliferation

The T lymphocyte-derived cytokine, interleukin-4 (IL-4), was found to inhibit dose dependently basal DNA synthesis of cultured non-neoplastic human astrocytes isolated from epilepsy white matter tissue. The mitogenic effect of tumor necrosis factor on astrocytes was also inhibited by IL-4, and the inhibitory effect was abrogated by anti-IL-4 antibody but not by irrelevant IgG. Immunofluorescent analysis indicated significantly reduced numbers of glial fibrillary acidic protein-positive astrocytes incorporating nuclear bromodeoxyuridine in IL-4-treated cultures compared to control. These findings indicate that human adult astrocyte proliferation, in contrast to that reported for endothelial cells or fibroblasts, is sensitive to down-regulation by IL-4.