Bidirectional regulation of macrophage function by TGF-beta

The dual role of transforming growth factor-beta (TGF-beta) in modulating m acrophage function is an important concept gaining increasing recognition. In addition to its role as a 'macrophage-deactivating' agent, TGF-beta func tions as a monocyte activator, inducing cytokine production and mediating h ost defence. These functions are context-dependent, modulated by the differ entiation state of the cell, the local cytokine environment, and the local levels of TGF-beta in itself. In general, during the initial stages of infl ammation, TGF-beta locally acts as a proinflammatory agent by recruiting an d activating resting monocytes. As these cells differentiate specific immun osuppressive actions of TGF-beta predominate, leading to resolution of the inflammatory response. Increasing our understanding of the bidirectional re gulation of macrophage function will facilitate prediction of the ultimate outcome of modulating TGF-beta levels in vivo. (C) 1999 Editions scientifiq ues et medicales Elsevier SAS.