Characteristics of giant cells and factors related to the formation of giant cells in myocarditis.

Abstract
Giant cell myocarditis is a serious and frequently fatal inflammatory heart disease of which the etiology remains unknown. In the present study, we investigated the origin of multinucleated giant cells in myocarditis with the use of an experimental model. We also examined the factors relating to the formation of giant cells in myocarditis. Severe myocarditis characterized by the appearance of multinucleated giant cells was induced in Lewis rats by immunization with cardiac myosin in complete Freund's adjuvant. Two types of giant cells, foreign body giant cell-like and myocytelike, were observed in this myocarditis. Immunohistochemical studies revealed that both types of multinucleated giant cells were stained with OX42 and ED1 (macrophage markers) and were not stained with anti-desmin antibody and HHF35 (markers for muscle fibers). Therefore, it is likely that multinucleated giant cells in this myocarditis are derived from macrophages. During the course of the disease, the appearance of multinucleated gia...