Human astrocytes proliferate in response to tumor necrosis factor alpha

Two different human astrocytic cell lines derived from adult epilepsy surgical specimens were exposed in vitro to concentrations of 1-100 ng/ml recombinant tumor necrosis factor alpha (TNF alpha). Results indicated dose-dependent stimulation of DNA synthesis and proliferation. Both of these effects were abrogated by treatment with monoclonal antibody specific for TNF alpha but not by irrelevant murine IgG. Immunocytochemical characterization of TNF alpha-treated and control cultures indicated that greater than 98% of proliferating cells contained cytoplasmic glial fibrillary acidic protein (GFAP), and were therefore astrocytic in nature. These studies demonstrate that growth of adult human non-neoplastic astrocytes is stimulated by TNF alpha, an inflammatory cytokine produced primarily by macrophages but also by astrocytes.