THE ROLE OF MACROPHAGES IN WALLERIAN DEGENERATION

The present review focuses on macrophage properties in Wallerian degen eration. The identification of hematogenous phagocytes, the involvemen t of cell surface receptors and soluble factors, the state of activati on during myelin removal and the signals and factors leading to macrop hage recruitment into degenerating peripheral nerves after nerve trans ection are reviewed. The main effector cells in Wallerian degeneration are hematogenous phagocytes. Resident macrophages and Schwann cells p lay a minor role in myelin removal. The macrophage complement receptor type 3 is the main surface receptor involved in myelin recognition an d uptake. The signals leading to macrophage recruitment are heterogeno us and not yet defined in detail. Degenerating myelin and axons are su ggested to participate. The relevance of these findings for immune-med iated demyelination are discussed since the definition of the role of macrophages might lead to a better understanding of the pathogenesis o f demyelination.