Giant cell stromal reaction in squamous cell carcinomata. Electronmicroscopic and ultrahistochemical observations on the genesis and functional activity of multinucleated giant cells in bleomycin-induced tumor regression

Cooperative phagocytosis of solid tumours by macrophages triggers durable anti-tumour responses

In solid tumours, the abundance of macrophages is typically associated with a poor prognosis. However, macrophage clusters in tumour-cell nests have been associated with survival in some tumour types. Here, by using tumour organoids comprising macrophages and cancer cells opsonized via a monoclonal antibody, we show that highly ordered clusters of macrophages cooperatively phagocytose cancer cells to suppress tumour growth. In mice with poorly immunogenic tumours, the systemic delivery of macrophages with signal-regulatory protein alpha (SIRPα) genetically knocked out or else with blockade of the CD47-SIRPα macrophage checkpoint was combined with the monoclonal antibody and subsequently triggered the production of endogenous tumour-opsonizing immunoglobulin G, substantially increased the survival of the animals and helped confer durable protection from tumour re-challenge and metastasis. Maximizing phagocytic potency by increasing macrophage numbers, by tumour-cell opsonization and by disrupting the phagocytic checkpoint CD47-SIRPα may lead to durable anti-tumour responses in solid cancers.

Absence of multinucleated giant cell reaction as an indicator of tumor progression in oral tongue squamous cell carcinoma

PURPOSE

The aim of this study was to evaluate the presence and distribution of multinucleated giant cell (MGC) reactions in 61 cases of OTSCC and to verify the association of this microscopic finding with clinicopathological parameters (gender, age, tumor size/extent, regional lymph node metastasis, distant metastasis, clinical stage, and histopathological grade of malignancy).

METHODS

Clinical data were collected from medical records and the histopathological grade of malignancy of OTSCCs was evaluated using the World Health Organization (WHO) grading system. The presence and distribution of MGC reaction in high power fields (HPFs) were evaluated in hematoxylin-eosin-stained histological sections. In all cases containing MGCs, immunohistochemical analysis for CD68 was performed in order to confirm the histiocytic nature of these cells.

RESULTS

Twenty-one (34.4%) cases had MGC reactions, with a higher frequency of the focal distribution pattern (57.1%). All MGCs were immunohistochemically positive for CD68. The absence of MGC reaction was significantly associated with regional lymph node metastasis (PR: 2.75; 95% CI 1.05-7.20; p = 0.027), advanced clinical stage (PR: 3.37; 95% CI 1.28-8.85; p = 0.006), and moderately/poorly differentiated tumors (PR: 3.36; 95% CI 1.51-7.48; p = 0.001). No significant associations were observed between the distribution of MGCs and clinicopathological parameters (p > 0.05).

CONCLUSION

Taken together, the results of this study suggest that the absence of MGC reaction may represent an indicator of tumor progression in OTSCCs.

Formation of giant cells in vivo

In vivo, the development of multinucleate giant cells in granulomas always proceeds in accordance with a given mode (simultaneous phagocytosis--fusion--unordered multinucleate giant cells--ordered multinucleate giant cells). This mode is both quantitatively and qualitatively modifiable, showing a dependence on the quantity, shape, size, and digestibility of the phagocytic material: on uncoated coverslips implanted i.p. in rats, only a few small syncytia develop, bit by bit, on coverslips coated with phagocytotic material, on the other hand, numerous very large, always initially unordered, multinucleate syncytia showing simultaneous aggregation around large phagocytic objects are seen. These can develop into ordered giant cells of the Langhans type, by re-distribution of the cytoplasmic contents, but only when most of the phagocytosed material has been digested. Actively phagocytosing mononuclear macrophages, which coalesce or have already fused to form syncytia frequently develop various types of junctions that probably have the same function in granulomas as in epithelia. Pentalaminar structures in multinucleate giant cells are frequently observed in close conjunction with residual phagocytic material and obviously represent outer cell-membranes that have coalesced during fusion and been incorporated into the cytoplasm. The clear zones surrounding such areas probably represent an element of the cytoskeleton.

Centrioles, microtubules and microfilaments in activated mononuclear and multinucleate macrophages from rat peritoneum: electron-microscopic and immunofluorescence microscopic studies

In male Wistar rats of the BD I strain, mononuclear macrophages and multinucleate giant cells obtained from the peritoneum 1 day to 5 weeks after implantation of coverslips coated with dermoid cyst sebum, were examined by light microscopy and immunofluorescence microscopy, using antibodies specific for actin and tubulin and also by scanning and transmission electron microscopy. In activated mononuclear macrophages, microtubules radiate from the centrioles, situated in the perinuclear area, into the cytoplasm and the major cell processes. Microfilaments form a dense meshwork beneath the plasmalemma. When mononuclear macrophages fuse to form multinucleate giant cells, the initially unordered ("Foreign body") syncytia still reveal the original distribution patterns of centrioles, microtubules and microfilaments similar to those seen in the individual cells. In the ordered (Langhans) multinucleate giant cell all centrioles are accumulated in a main pluricorpuscular central group. Centrioles are the initiating and organising centres in the formation of microtubules. From the centrioles microtubules extend into the entire cytoplasm of the syncytium as a uniformly organised, stellate, radial system. The centrosphere, which is characteristic for ordered multinucleate giant cells, seems free from microfilaments, which form a ring-shaped woven network encircling the nuclei. Depolymerisation and inhibition of microtubules upon exposure to colchicine, indicates that both the organisation of the cytoplasm and the cellular movements depend on the undisturbed coordination of centrioles, microtubules and microfilaments. This applies also to the fusion of mononuclear macrophages to form syncytia, the ordering processes within multinucleate giant cells, and the function of ordered giant cells.

Osteoclastoma-like giant cell tumor of the liver

A rare, osteoclastoma-like giant cell tumor developed in the macronodular cirrhotic liver of an 87-year-old man. Histogenetically, the tumor was considered to be of reticuloendothelial cell (Kupffer cell) origin. A brief review of the literature concerning the extraosseous giant cell tumors is included in this report.

Exocytosis by macrophage polykarya: an ultrastructural study

Macrophage polykarya selectively secrete their lysosomal contents directly into the extracellular space or into the intracytoplasmic membranous labyrinth. Fusion of the lysosomal membrane with the plasmalemma or with the cytoplasmic labyrinth results in the release of the lysosomal contents. The labyrinth, however, was shown to be essentially similar to the plasmalemma, hinting that comparable mechanisms are involved in both instances. The process of secretion is unrelated to motility and phagocytosis and may be important in the extracellular degradation of biological material.