We have previously shown that γδ T cells traffic to the CNS during EAE with concurrently increased expression of β 2-integrins and production of IFN-γ and TNF-α. To extend these studies, we transferred bioluminescent γδ T cells to WT mice and followed their movement through the acute stages of disease. We found that γδ T cells rapidly migrated to the site of myelin oligodendrocyte glycoprotein peptide injection and underwent massive expansion. Within 6 days after EAE induction, bioluminescent γδ T cells were found in the spinal cord and brain, peaking in number between days 10 and 12 and then rapidly declining by day 15. Reconstitution of γδ T cell-/- mice with γδ T cells derived from β 2-integrin-deficient mice (CD11a, -b or -c) demonstrated that γδ T-cell trafficking to the CNS during EAE is independent of this family of adhesion molecules. We also examined the role of γδ T-cell-produced IFN-γ and TNF-α in EAE and found that production of both cytokines by γδ T cells was required for full development of EAE. These results indicate that γδ T cells are critical for the development of EAE and suggest a therapeutic target in demyelinating disease. © 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.