Modulation of Fas-Ligand (Fas-L) on human microglial cells: an in vitro study

The expression of Fas-ligand (Fas-L) on microglia could be relevant in mult iple sclerosis immunopathology. The present study was performed to evaluate in vitro the expression of Fas-L in human microglial cells both unstimulat ed and after stimulation with IFN-gamma, beta-IFN-1b and beta-IFN-1b+IFN-ga mma. Cells were stimulated for 6,12,24 and 48 h. Surface Fas-L was evaluate d by flow cytometry, total Fas-L by Western blot, whereas mRNA for Fas-L wa s measured by RT-PCR. We also evaluated the capacity of microglial cells to induce, in vitro, apoptosis on Fas-positive T leukemia Jurkat cells. Our r esults showed a constitutive expression of Fas-L on microglia. IFN-gamma do wnregulated the expression of the molecule, while beta-IFN-1b and beta-IFN- 1b+IFN-gamma did not. The amount of surface Fas-L was related to the abilit y of microglial cells to induce apoptosis in Fas-positive target cells, whi ch was partly inhibited by blockade of the Fas-Fas-L pathway. (C) 2000 publ ished by Elsevier Science B.V. All rights reserved.