A study to analyze the origin of tumor cells in malignant fibrous histiocytomas. A multiparametric characterization.

To study the derivation of tumor cells of malignant fibrous histiocytomas (MFH), their phenotypical marker profile was investigated and compared with those of malignant histiocytosis (MH) and of different types of soft tissue tumors (STT). The presence of the following markers was investigated: on paraffin sections, alpha-1-antichymotrypsin (ACT); on frozen sections antigens associated with lymphocytes, macrophages and fibroblasts, the enzymes acid phosphatase, nonspecific esterase, and beta-glucuronidase; and, on isolated and cultured cells, the receptors for EA-gamma and complement. Furthermore, the capacity to phagocytose sensitized erythrocytes and carbon particles was studied in vitro. MFH tumor cells and a part of other types of STT shared the expression of ACT and lysosomal enzymes with MH. They differed, however, from MH by the absence of monocyte/macrophage-associated antigens and by the expression of fibroblast-associated antigens, which property they had in common with other STT. MFH tumor cells were not able to form rosettes or to phagocytose Ig-sensitized erythrocytes, but they showed phagocytosis of carbon particles. The results strongly indicate that MFH tumor cells originate from (primitive) fixed mesenchymal cells and are not related to monocyte-derived histiocytes.