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© Dirk Biddle
Giant cells are transformed macrophages or monocytes, mediated by TH (CD4+) helper cells. There are three main types of giant cell seen in chronic inflammation and each has a typical histopathological feature. Langharn's cell: the giant cell has a peripheral ring (horseshoe) of nuclei in the cytoplasm. Foreign body giant cell: the nuclei are centrally placed and haphazardly overlap each other. Touton's cells: there is a ring of nuclei separating a peripheral clear cytoplasm from an eosinophilic central cytoplasm.
Little is known about the exact mechanisms behind the formation of giant cells, however two processes have been identified; first, cell fusion (syncitium), where dendritic cell-specific transmembrane protein (DC-STAMP) is proposed to play an important role in this process(1). And second, interference with the process of mitosis wherein daughter cells do not separate from the mother progenitor (amitotic division). Here it has been shown that X-rays, asbestos fibres and probably other toxic substances and even vitamin E (by bolstering the immune response) can play a role.
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1. Vignery, A. (2005) Macrophage fusion: The making of osteoclasts and giant cells. Journal of experimental Medicine, 202(3), 337-340
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