Monoclonal antibodies against SU-DHL-1 cells stain the neoplastic cells in true histiocytic lymphoma, malignant histiocytosis, and Hodgkin's disease.

Three murine monoclonal antibodies, named 2H9, 1E9 and 1A2, were produced after immunization of BALB/c mice with cells of the SU-DHL-1 cell line from a true histiocytic lymphoma. In frozen sections from various lymphomas, 2H9 and 1A2 selectively stained the cell membranes of neoplastic cells in true histiocytic lymphoma and Hodgkin's disease. Antibody 1E9 stained the nuclear membranes of the tumor cells in true histiocytic lymphoma and malignant histiocytosis. No staining was seen in 56 cases of B and T cell lymphoma. Several tissue culture cell lines, including T cell acute lymphoblastic leukemia and pre-B cell lines, were not stained. With 2H9, however, a positive reaction was noted for two Epstein-Barr virus (EBV)-positive African Burkitt's lymphoma cell lines (Daudi and P3HRI), one human T cell lymphoma/leukemia-virus-positive cell line (HUT 102), and one EBV-transformed normal B lymphoblastoid cell line (RPMI 8057). In normal lymphoid tissues, 2H9 and 1E9 reacted with the nuclear membranes of histiocytes and interdigitating reticulum cells, whereas 1A2 stained only rare cells of an unknown type. All three antibodies failed to react with B or T cells in frozen tissue sections of normal lymphoid tissues. The use of these three antibodies should facilitate the diagnosis of histiocyte and interdigitating reticulum (IR) cell-related neoplasms, namely, true histiocytic lymphoma, malignant histiocytosis, and Hodgkin's disease. True histiocytic lymphoma and Hodgkin's disease exhibit similar reactivities with these three and with two other monoclonal antibodies (HeFi-1 and Tac), suggesting that these two types of lymphoma are related. In contrast, malignant histiocytosis was negative for 2H9, 1A2, Tac, and HeFi-1. The difference in the phenotypic expression of true histiocytic lymphoma and malignant histiocytosis indicates that they are two different disease entities.