Comparative immunohistochemical investigation of markers for malignant histiocytes

Abstract

The presence of lysozyme, alpha 1-antitrypsin (AT), alpha 1-antichymotrypsin (ACT), and cytoplasmic receptors for peanut and soy bean agglutinin and for concanavalin A (PNA, SBA, and ConA, respectively) was investigated in formalin-fixed, paraffin-embedded material from 16 cases of malignant histiocytosis. The tumors in these cases did not show phenotypic characteristics of T or B cells. Lysozyme and AT especially were found less frequently in tumor cells from malignant histiocytosis than in normal histiocytes, whereas ACT and binding sites for the lectins were maintained during malignancy. Specimens from 44 per cent of the cases were positive for lysozyme, 56 per cent for AT, 82 per cent for ACT, 88 per cent for PNA receptors, 94 per cent for SBA receptors, and 100 per cent for ConA receptors. Tumor cells from B- and T-cell lymphomas were negative for these markers. Plasma cells, granulocytes, and fibroblasts sometimes bound ConA, but not PNA or SBA. The cases of malignant histiocytosis were subdivided into three groups on the basis of grade of differentiation. The tumor cells from the cases in group 1 showed the highest degree of differentiation, those from group 2 an intermediate degree, and those from group 3 the lowest degree. Mitotic activity was present mainly in groups 1 and 2. Lysozyme was present most frequently in groups 1 and 3 and in cases with the least mitotic activity. Expression of AT was decreased in groups 2 and 3. The presence of phagocytosis, which is not obligatory for the diagnosis, was always correlated with ACT staining. The presence of binding sites for these lectins can be considered a useful marker for malignant histiocytes.