The role of TNF-alpha during Wallerian degeneration

The role of TNF-alpha in the course of Wallerian degeneration of the sciati c nerve was studied in control and TNF-alpha deficient mice. In control ani mals, the characteristic phenomena of Wallerian degeneration such as axon a nd myelin degeneration as well as macrophage recruitment with subsequent my elin removal were observed. In TNF-alpha deficient mice, in contrast, macro phage recruitment into the degenerating nerves was impaired resulting in a delayed myelin removal. However, the myelin phagocytic capacity of macropha ges was not affected as it could be demonstrated by a similar myelin load o f control and TNF-alpha deficient macrophages. These data indicate that the main function of TNF-alpha during Wallerian degeneration is the induction of macrophage recruitment from the periphery without affecting myelin damag e or phagocytosis. (C) 2000 Elsevier Science B.V. All rights reserved.