Macrophage-histiocytes in malignant lymphoma, small lymphocytic type (well-differentiated lymphocytic lymphoma)

A special linker between macrophage and hematopoietic malignant cells: membrane form of macrophage colony-stimulating factor

The membrane form of macrophage colony-stimulating factor (mM-CSF) is an alternative splicing variant of this cytokine. Although its high expression was detected in hematopoietic malignancies, its physiologic and pathologic roles in hematopoietic system have not been established. In this report, stable transfectant clones expressing mM-CSF (Namalwa-M and Ramos-M) were obtained, which showed reduced proliferation potential in vitro. Moreover, the in vivo study showed that Namalwa-M and Ramos-M exhibited enhanced oncogenicity in tumor size in nude mice model, which could be inhibited by M-CSF monoclonal antibody. A remarkable increase in infiltrating macrophage and the vessel densities was found in tumor tissues formed by lymphoma cell lines that stably expressed mM-CSF, which suggested the involvement of macrophages in this process. The in vitro results using coculture system showed that macrophages could promote Namalwa-M and Ramos-M proliferation and activate extracellular signal-regulated kinase/mitogen-activated protein kinase signal pathway. In addition, the expression of murine origin vascular endothelial growth factor, basic fibroblast growth factor, and hepatocyte growth factor was elevated in Namalwa-M formed tumor tissues. These results suggested that mM-CSF should be a positive regulator in the development of hematopoietic malignancies by abnormally activating infiltrating macrophages, which in turn promote the malignant development. Thus, mM-CSF may be a critical linker between macrophages and malignant cells in the development of hematopoietic malignancies.

Ultrastructure and lectin histochemistry of equine cutaneous histiolymphocytic lymphosarcomas

Tissues from subcutaneous lymphosarcomas and regional lymph nodes were examined by light and electron microscopy and by lectin histochemistry. Tumors were composed of two major cell types: small lymphocytes with few organelles and pleomorphic histiocytic cells with undulant surfaces, large numbers of cytoplasmic vacuoles, and many mitochondria with large crystalline inclusions. A large gram-positive coryneform bacterium was isolated from tumor nodules but was not identified morphologically in tumor tissues. Evaluation of sections of tumors with lectins as histochemical probes revealed three staining patterns: 1) lectin labeling histiocytic cells only (wheat germ, succinylated-wheat germ, Phaseolus vulgaris and soybean agglutinins); 2) lectins labeling histiocytic, interstitial and some lymphoid cells (concanavalin A, and Pisum sativum, Lens culinaris, and Ricinus communis I agglutinins); and 3) lectins failing to label any cell (peanut, Sophora japonica, and Ulex europaeus I agglutinins). In the lymph node, macrophages were labeled by lectins of groups 1 and 2; interdigitating reticular cells were labeled by group 2 lectins. Lectin staining of histiocytic cells in tumor tissues suggested that these were reactive cells and that lymphoid cells were the primary neoplastic component.

Mac 387 antibody and detection of formalin resistant myelomonocytic L1 antigen

The murine monoclonal antibody Mac 387 was raised against a purified protein fraction obtained from human monocytes. By immunoblotting experiments, Mac 387 was shown to react with a previously defined antigen called L1; this is a multichain myelomoncytic protein of about 36 Kd which shows sequence homology with the cystic fibrosis antigen. The L1 protein is present in the cytoplasm of virtually all resting peripheral neutrophils and monocytes; it is also variably expressed on the plasma membrane of these cells, possibly as a secretory product. Because the L1 antigen is resistant to denaturation by formalin, its tissue distribution can be studied in routinely processed biopsy material. In a wide variety of specimens Mac 387 was shown by immunohistochemical analysis, to produce a cytoplasmic staining pattern concordant with that of a well defined polyclonal antibody to the L1 antigen. Cytoplasmic reactivity was obtained with granulocytes and infiltrating macrophages but generally not with several categories of dendritic cells. In addition, squamous epithelium of mucous membranes was strongly positive, in contrast to normal epidermis.

Stromal macrophage-histiocytes in Hodgkin's disease. Their relation to fever

Morphologic variations of Concanavalin A-binding histiocytes were studied in biopsy specimens of 140 untreated patients with Hodgkin's disease (72 asymptomatic, and 68 with constitutional symptoms). Fever was the most common symptom, present in 57 of the 68 patients. Three morphologic types of stromal histiocytes were recognized: medium-sized cells similar to those seen in reactive follicles, characterized by distinct cytoplasm and cell borders, and uniform nuclei (Type A); damaged-appearing Type A cells marked by rarefied or ragged cytoplasm, disrupted or indistinct cell borders, and varying sized nuclei (Type B); and large spindling or stellate cells (Type C). Type A cells were predominant in 52 patients; Type B cells in 51; Type C cells in seven; and Type A cells were mixed with Type B in 30. Fever was present in one of 52 patients (1.9%) with Type A predominance; 43 of 51 (84.3%) with Type B cell predominance; none of seven (0%) with Type C predominance; and 13 of 30 (43.3%) with mixed Type A and B cells. Logistic regression analysis of the data showed that the association of fever with Type B cell predominance was highly significant, and was not attributable to the known association of fever with other variables. Morphologic evidence suggests that fever in Hodgkin's disease may be a clinical manifestation of damaged macrophage-histiocytes rather than an acute-phase response of inflammatory or immune reaction.

Peanut agglutinin. A useful marker for histiocytosis X and interdigitating reticulum cells

We studied the peanut agglutinin (PNA) staining patterns of histiocytosis X (H-X) (three cases, including one case of Letterer-Siwe disease) and well-characterized cases of malignant histiocytosis (two cases) and monoblastic leukemia (one case) in paraffin-embedded specimens. H-X cells showed staining identical to that of interdigitating reticulum cells, with unique paranuclear and cell surface deposits of reaction products. Thus, H-X cells were easily distinguished from benign macrophage-histiocytes, which show diffuse cytoplasmic staining, and malignant cells of malignant histiocytosis and monoblastic leukemia, which did not stain with PNA, PNA staining proved more useful than Leu-M1 antibody for this purpose, since neither interdigitating reticulum cells in ten reactive lymph nodes nor Langerhans'-type cells in three cases of H-X were stained with Leu-M1 antibody. These observations support a close relationship between H-X cells and interdigitating reticulum cells, and demonstrate the usefulness of PNA for the identification of these cells in paraffin-embedded material.