This study reports that in Schwann cell tissue culture the administration of the two pro-inflammatory cytokines, interleukin-1 beta (IL-1beta) and interferon-gamma (IFN-gamma), at different dosages, singly or in combination, can induce apoptosis and/or mitosis. Schwann cell apoptosis was maximal within 24 h of stimulation with 50 U/ml of IFN-gamma, while proliferation was at its peak within 24 h with 10 U/ml IL-1beta, and both processes decreased progressively by 48 and 72 h. Moreover, the combination of the two cytokines did not show any synergistic effect. These data can be interpreted as a possible involvement of pro-inflammatory cytokines not only in myelin disruption but also in promoting remyelination. (C) 2002 Elsevier Science B.V. All rights reserved.