MORPHOLOGICAL ANALYSIS OF MULTINUCLEATED GIANT-CELLS OCCURRED IN EXPERIMENTAL AUTOIMMUNE MYOCARDITIS

Our previous study reported the rich existence of multinucleated giant cells in an autoimmune myocarditis experimentally induced in rats. Th e present study investigated the histochemical and ultrastructural cha racteristics of these giant cells. Histochemistry for an acid phosphat ase clearly demonstrated multinucleated giant cells dispersed at the i nflammatory foci. Ultrastructurally, the giant cells were shown to be single cells, but not clustered cells. Their ultrastructural character istics were very similar to the basic features of macrophages, except that the giant cells mere poor in lysosomes and phagosomes. It was not iceable that some macrophages possessed three or more nuclei, displayi ng an intermediate form between mononuclear macrophages and multinucle ated giant cells. These findings suggest that the giant cell in the ex perimental autoimmune myocarditis is a single multinucleated cell, and possibly derived from macrophages by cell-to-cell fusion.