Mohammad R. Parwaresch

MALIGNANT LYMPHOMAS OF B-CELL TYPE

Abstract The immunoglobulin (1g) concentration in tissue homogenates of 28 malignant lymphomas and 3 myelomas was examined and compared with that of 25 normal lymph-node homogenates. 15 cases showed normal or reduced Ig values and 16 showed a significant increase of one of the Ig types. IgA had increased in 1, IgG in 4, and IgM in 11 cases. Histologically these tumours were classified as: reticulum-cell sarcoma (4), chronic lymphocytic leukaemia (3), multiple myeloma (3), lymphoblastic lymphosarcoma (2), lymphocytic lymphosarcoma (1), lymphatic plasma-cell leukaemia (1), unclassifiable lymphoma (2).

Liver findings in generalized mastocytosis. A clinicopathologic study

Although the liver is one of the four organs most often involved in generalized mastocytosis (GM), little is known about macroscopic and microscopic liver findings in this rare disease. This study included 182 patients with GM (confirmed in most by bone marrow histologic study), comprising 52 cases of our own and 130 reported in the literature. Hepatomegaly was found in 131 (72%) of the 182 patients, cirrhosis in seven (4%), and periportal fibrosis in 25 (14%). Mast cell (MC) infiltration of the liver was confirmed histologically in 77 (42%). Liver specimens were available for further histologic investigation in 11 of our own cases of GM. Nine of these contained MC aggregates. Mast cells were found predominantly in the portal tracts but numerous MC also were loosely scattered throughout the sinusoids. Diagnostic confusion of GM with reactive lesions of the liver is unlikely to occur since MC, according to our own observations and the available literature, are found only in very low numbers in normal liver tissue, where they occur mainly in the portal tracts. Reliable identification of MC does, however, require special stains, like Giemsa, toluidine blue, or naphthol AS‐D chloroacetate esterase.

Ki-M2R, a new specific monoclonal antibody, discriminates tissue macrophages from reticulum cells and monocytes in vivo and in vitro.

Utilizing rat peritoneal macrophages as the immunogen, a new monoclonal antibody enabling differential monitoring of the mononuclear phagocyte system (MPS) by immunohistochemistry has been raised. Designated Ki‐M2R, this antigen could be detected with the immune alkaline phosphatase reaction on all macrophages including those of bone marrow, lymphatic sinuses, lymphoid follicles, splenic red pulp, and von Kupffer cells of the liver, as well as on macrophages of connective tissue, renal interstitial tissue, serous cavities, and gastrointestinal tract. Langerhans cells—the MPS‐derived reticulum cells of the epidermis—interdigitating reticulum cells, and dendritic reticulum cells of lymphoid follicles were invariably negative. Blood monocytes were rendered positive only after evolving into macrophages upon appropriate stimulation. Thus, Ki‐M2R selectively labels monocytes after transformation into macrophages.

Combined immunohistochemical staining for surface IgD and T-lymphocyte subsets with monoclonal antibodies in human tonsils

SummaryThe aim of the present paper is to detect two different antigens simultaneously in a single slide. In cryostat sections of human tonsils, B-lymphocytes of follicle mantle-bearing surface IgD were immunostained with the alkaline phosphatase method using monoclonal anti IgD. The subsequent staining for T-lymphocyte subsets (T-helper and T-suppressor lymphocytes) was performed again with the alkaline phosphatase method using one of the monoclonal antibodies OKT 4, OKT 8, Leu 3a, Leu 2a. The best results with the alkaline phosphatase method were achieved using naphthol AS phosphate and Fast Blue BB for the revelation of the first antigen and naphthol AS-BI phosphate and diazotized New Fuchsin for the second.

Lymph node findings in generalized mastocytosis

Lymph nodes from 21 cases of generalized mastocytosis were studied histologically to confirm or exclude mast cell infiltration, and to investigate their micro‐architecture. Mast cell infiltrates were detected in 17 (80%) of the lymph nodes and were found mainly in the medullary cords and sinuses. Diffuse infiltration was seen in 14 cases and focal infiltration in three cases. The following pathological findings were frequently observed: germinal centre hyperplasia (n= 14), which is probably a nonspecific finding; and hyperplasia of small blood vessels, which sometimes resembled high endothelial venules (14), eosinophilia (8), plasmacytosis (7) and collagen fibrosis (6), all of which may well be related to the effects of mediators released by mast cells. Infiltrates of acute or chronic myeloid leukaemia were seen in six lymph nodes. Division of the cases into two prognostically different groups, i.e. systemic mastocytosis, in which the skin lesions of urticaria pigmentosa are present and the prognosis is favourable, and malignant mastocytosis, in which there is no cutaneous involvement and the prognosis is poor, revealed that all six lymph nodes exhibiting leukaemic infiltrates came from the malignant mastocytosis group; eosinophilia, plasmacytosis and fibrosis were seen significantly more often in malignant than in systemic mastocytosis, but blood vessel hyperplasia and germinal centre hyperplasia were encountered with the same high frequency in both groups; and mast cell atypia tended to be more pronounced in malignant mastocytosis; this diagnosis could therefore easily be missed without naphthol AS‐D chloroacetate esterase staining. In four lymph nodes no mast cell infiltrates could be detected, although two of these exhibited eosinophilia, plasmacytosis and fibrosis. As only one example of the lymphadenopathic variant of generalized mastocytosis was found amongst 181 archive and published cases reviewed, this would appear to be very rare.

Ki-M7 monoclonal antibody specific for myelomonocytic cell lineage and macrophages in human.

We describe a new monoclonal antibody, termed Ki-M7, which is specific to human myelomonocytic cell lineage and macrophages, as tested by immunohistochemical methods. Ki-M7 recognizes an intracytoplasmic antigen of molecular weight 29,000. Ultrastructurally, the antigen is localized in the lysosome and phagosome compartments and seems to be involved in generation of oxygen radicals during the respiratory burst. Dendritic cells, such as dendritic reticulum cells of lymphoid follicles and interdigitating reticulum cells of lymphoid T-zones, considered as accessory cells of the B- and T-cell immune response, respectively, do not show any reactivity with monoclonal antibody Ki-M7. Ki-M7 seems to be an appropriate reagent to clearly differentiate between the phagocytosing and the immune accessory population of the human monocyte/macrophage system.

Diversity of the human monocyte/macrophage system as detected by monoclonal antibodies.

Four monoclonal antibodies against the human monocyte/macrophage system, termed KI‐M1, KI‐M6, KI‐M7, and KI‐M8, are described with regard to their immunohistochemical tissue distribution pattern and their subcellular reactive sites. The differences found applying these analyses are also reflected by the various molecular weights of the recognized antigens. Based on these data it is proposed that the monocyte/macrophage system can be divided into the phagocytosing compartment on one hand and the immune accessory compartment on the other hand; the latter constitutes the interdigitating reticulum cells, the indeterminate dendritic cells, and the Langerhans cells, as well as the follicular dendritic cells (dendritic reticulum cells) as the accessory cells for T‐ and B‐cell immune response, respectively.

Kinetics of Kupffer cells as shown by parabiosis and combined autoradiographic/immunohistochemical analysis

SummaryLeucocytes from syngeneic rats were labeled with tritiated thymidine and donor and recipient rats were connected by a bilateral arteriovenous shunt. Based on the time-dependent label index and labeling intensity, it was concluded that Kupffer cells, the resident macrophages of the liver, have a half-life of 12.4 days and originate from monocytes undergoing one mitosis within 8.4 days after immigration into the liver. The labeled cells were easily identified as Kupffer cells by their selective immunoreactivity with the monoclonal antibody Ki-M2R which is specific for phagocytosing macrophages in the rat. The applicability of combined autoradiography/immunohistochemistry for the identification of other poorly defined macrophage subpopulations is shown.

Myofibroblast as a major cellular constituent of villous stroma in human placenta

The human placenta requires contractile structures to generate energy for blood propulsion. Smooth muscle cells are not present in significant numbers in the human placenta while fibroblasts lack effective contractile properties. This study provides the following evidence that the stromal cells of the placental villi, cotyledonary septa and perivascular connective tissue are myofibroblasts. (I) Stromal cells are strongly positive for dipeptidylpeptidase IV (EC 3.4.14.5) which occurs exclusively in myofibroblasts as far as connective tissue cells are concerned. (2) The isoenzyme pattern of the placental dipeptidylpeptidase IV is identical to that of myofibroblasts in palmar fibromatosis on isoelectric focusing. (3) Antibodies raised against isolated placental dipeptidylpeptidase IV cross-react with dipeptidylpeptidase IV from myofibroblasts of palmar fibromatosis as shown by immunohistochemistry. (4) On electron microscopic examination, stromal cells present all the ultrastructural features of myofibroblasts. It is concluded that, except for the vascular component and a negligible number of Hofbauer cells, myofibroblasts make up nearly all the cellular constituents of human placental villous stroma.

M-CSF and M-CSF-receptor gene expression in acute myelomonocytic leukemias.

The role of hematopoietic growth factors in the pathogenesis of human leukemias is still obscure. In this study, RNA from 24 human acute myelomonocytic leukemias (AML) was used to analyze the expression of the macrophage colony stimulating factor (M-CSF) and its corresponding receptor (c-fms). Fifty percent of AML cells exhibited c-fms transcripts of regular length but at a lower level than in normal monocytes/macrophages. In most cases the reduced c-fms expression of AML cells was not associated with autostimulatory M-CSF expression. Only a few cases of AML showed co-expression of M-CSF and c-fms, which by contrast was regularly observed in cultivated blood monocytes and some tissue macrophage subsets. Higher levels of c-fms expression could be found in AMLs with a more mature monocytic immunophenotype. Permanent myelomonocytic cell lines expressed c-fms only after induction of monocytic differentiation. Neither the M-CSF gene nor the c-fms gene were rearranged in AML cells. In AML cells the homozygote genotype of the c-fms gene predominated. Our results do not provide evidence for the involvement of M-CSF and c-fms genes in human myeloid leukemogenesis. c-fms expression appears to indicate monocytic differentiation within the myelomonocytic lineage. We found autostimulatory M-CSF expression to be a physiologic feature of some tissue macrophages and hence not necessarily associated with neoplastic proliferation.