Immunologic marker analysis of normal and malignant histiocytes. A comparative study of monoclonal antibodies for diagnostic purposes.

The authors investigated the phenotype of "monocyte-derived histiocytes/macrophages" on frozen sections of various human tissues, in 12 histiocytic tumors, and in 15 large cell non-Hodgkin's lymphomas. The monoclonal antibodies (MAbs) considered specifically directed against antigens associated with monocytes/histiocytes included the following: Leu-M1, Leu-M3, Leu-M5, My4, My7, My8, My9, anti-Monocyte 1, anti-Monocyte 2, RFD-7, RFD-9, OKM1, and FMC17. The histiocytes in normal tissues and the tumor cells of the histiocytic malignancies expressed these antigens in various degrees. They were not reactive with MAbs specific for lymphocytes, myeloid cells, or Reed-Sternberg cells (Ki-1 antigen). Out of these 13 MAbs, only the labeling by MAb Leu-M3, Leu-M5, anti-Monocyte 1, and RFD-7 was restricted to normal and malignant monocytes/histiocytes. In combination with their broad labeling of different types of monocytes/macrophages, these MAbs are of value in differential diagnostic purposes to distinguish histiocytic malignancies from large cell lymphomas. However, none of the 13 MAbs can be considered as pan-histiocytic reagents because they did not recognize all cell types belonging to the mononuclear/phagocytic system.