Multinucleated giant cells

Recent studies directed toward developing a better understanding of the mol ecular and cellular biology basis of monocyte-derived multinucleated giant cell formation, function, and biologic activity are presented. In addition, HIV-1-infected T-lymphocyte syncytia and the significance of adhesion mole cule/ligand interactions in the formation of these syncytia are described. Interleukin-4 or interleukin-13 induction of monocyte-macrophage fusion pro vides a model for foreign body giant cell formation. On the other hand, int erferon-gamma induction of monocyte-macrophage fusion provides a model for Langhans' giant cell formation. Variations in monocyte-macrophage adhesion and fusion to form foreign body giant cells are provided by substrates with different surface chemistries. Recent advances in osteoclast biology have identified the role of tumor necrosis factor-alpha in regulating osteoclast bone resorption and receptor-ligand interactions and signal pathways for o steoclast activation. Although foreign body giant cells, Langhans' giant ce lls, and osteoclasts are derived from monocytes or monocyte progenitor cell s, the ways in which they are formed, whether induced by cytokines, recepto rs, or biologic activity, are markedly different. (C) 2000 Lippincott Willi ams & Wilkins, Inc.