Lymphocyte Emperipolesis in Human Glial Cells

Astrocytes have been observed to contain intact, viable lymphocytes within their cytoplasm (emperipolesis) in multiple sclerosis plaques and some brain tumors. This study characterizes the adhesive, emperipoletic and phagocytic properties of glial cells in culture. Human fetal and adult astrocytes engaged in adhesion and emperipolesis of lymphocytes. Emperipolesis, and not adhesion, was temperature- and cation-dependent. The CD8 and MHC Class I antigens played a role in emperipolesis. Lymphocytes most often remained viable within the cytoplasm of astrocytes but occasionally underwent lysis or caused disruption of the astrocyte intermediate filaments. The phenomenon of emperipolesis is distinct from phagocytosis, since microglia showed prominent phagocytic properties but did not engage in emperipolesis. Conversely, astrocytes were efficient emperipolites and rarely demonstrated phagocytic properties.     

Megakaryocytes emperipolesis in bone marrow of the patients with non-Hodgkin's lymphoma

Emperipolesis of hematopoietic cells within the cytoplasm of the megakaryocytes was most often described in association with various pathologic conditions. The aim of the research was estimation of the incidence of emperipolesis in the bone marrow of the patients with non-Hodgkin's lymphoma (NHL). 30 patients with different histological types of NHL (chronic lymphocytic leukaemia--CLL, hairy cell leukaemia--HCL, multiple myeloma--MM) in compliance with clinical stage of the disease, patient's age and sex were analyzed. Trephine biopsies of the bone marrow were carried out in fixative solution and paraffin embedding. Hematoxylin and eosin and monoclonal antibody CD 61 were applied on thin sections. Phenomenon of megakaryocytic emperipolesis in human bone marrow was found in 6 cases: in 5 cases in CLL and in 1 case in HCL. In most of them emperipolesis was related to single megakaryocytes. We observed in the cytoplasm of the megakaryocytes single hematopietic cells-most often lymphocytes, rarely eosinophilic granulocytes. We found no correlations between histological types of NHL, clinical stage of the disease, patients' age, sex and the incidence of megakaryocytic emperipolesis.     

Emperipolesis in a common breast malignancy. A case report

BACKGROUND: Emperipolesis is a phenomenon characterized by the presence of leukocytes/lymphocytes within the cytoplasm of other cells. The present report describes this unusual observation within epithelial cancer cells of the breast. CASE: A 52-year-old female presented with a hard, adherent lump over the right breast for one year. Fine needle aspiration and histopathologic examination of the tumor showed features of infiltrating duct carcinoma with emperipolesis as a striking feature of the tumor cells. The tumor showed a near-total response to neoadjuvant chemotherapy. CONCLUSION: The mechanism and biologic significance of emperipolesis in producing a near-total response to neoadjuvant chemotherapy in the present case suggest its role in inducing a tumoricidal effect, possibly involving a cascade of chemokines.     

Tumour cell interactions in vitro

After addition of dibutyryl cAMP to spinner flask cultures of JB-1-E tumour cells an increase in the number of examples of emperipolesis was observed. Ruthenium red staining of the cells revealed a conspicuous staining of the cell membrane of the outer cell, while that of the inner cell was unstained. The differences in staining properties of the cell membranes of the outer and inner cells involved in emperipolesis and apparently viable inner cells make it evident that coexistence of cells--one within another--is possible.     

Motility of L 5222 rat leukemia cells in the flattened state. Evidence against emperipolesis.

Emperipolesis is the term for the assumed penetration of living cells into other living cells. As reported earlier, L 5222 rat leukemia cells, migrating in vitro, change from a spherical to a spread configuration when they meet flat cells, and continue to move in this shape within the contours of the target cells. Whether or not this close cellular association corresponded to emperipolesis could not be determined with phase and interference contrast cinemicrography alone. In combination with transmission electron microscopy, it could be demonstrated that the compartment, in which the spread leukemia cells move, is not the cytoplasm of the target cells, but the narrow space created by the target cells and the underlying glass surface. Thus, emperipolesis could be ruled out for L 5222 leukemia cells. On this basis the reported observations on emperipolesis are reviewed, and a critical attitude regarding the occurrence of emperiopolesis in general is advocated.     

IpaB of Shigella flexneri causes entry into epithelial cells and escape from the phagocytic vacuole.

By creating mutations within the Shigella flexneri ipaB gene, we have demonstrated that the invasion of epithelial cells is a three-step process encompassing adhesion on the cell surface, entry and lysis of the phagocytic vacuole allowing subsequent access to the cytoplasm. SC403, an insertion mutant which lacks expression of IpaB but still expresses downstream genes, has been particularly studied. It is non-invasive, does not elicit actin polymerization, but binds to HeLa cells indicating that an adhesion step occurs immediately prior to the entry process. The consequence of the inactivation of ipaB on the intracellular behaviour of S.flexneri was investigated using the macrophage cell line J774. SC403 was unable to lyse the phagocytic vacuole; moreover, this strain did not display the contact mediated haemolytic activity characteristics of Shigella. In addition to being a major component of the invasion complex, IpaB acts as a membrane-lysing toxin enabling escape to the cytoplasmic compartment.     

Emperipolesis as a key feature in imprint cytology of the thymus. A report of two cases

BACKGROUND: Imprint cytology of the thymus has not received much attention. Cytology of the thymus is important because the uninvolved thymus may be needled during aspiration procedures. CASES: In two cases, during surgery for carcinoma of the thyroid, we received thymic tissue mistakenly sampled as a pretracheal lymph node for frozen section to rule out metastasis. Imprint smears were studied. The presence of thymocytes in the cytoplasm of thymic epithelial cells (emperipolesis) was the most significant feature in the imprints. However, it was not detected on histology. CONCLUSION: Thymic epithelial cells provide mechanical support and play a major role in the maturation of lymphocytes (thymocytes). They are observed as emperipolesis on imprint cytology. Its utility in identifying thymic cells in aspiration cytology needs to be investigated.     

Emperipolesis--a peculiar feature of megakaryocytes as evaluated in chronic myeloproliferative diseases by morphometry and ultrastructure

A combined morphometric and ultrastructural study was performed on so called emperipolesis or internal wandering of myeloid cells in the cytoplasm of large mature megakaryocytes. Measurements were made on material from a total of 115 patients comprising a normal control group and 5 groups with subtypes of chronic myeloproliferative diseases, including primary (essential, idiopathic) thrombocythemia (PTH). A significant increase in this peculiar phenomenon was noted in myeloproliferative disorders and especially in PTH where the frequency of emperipolesis showed a positive correlation with the number of anuclear cytoplasmic fragments sectioned, with the circular deviation of the shapes of megakaryocytes and with the extent to which the peripheral thrombocyte count was elevated. Electron microscopy in selected cases displayed the integrity of the plasma membranes of engulfed hematopoietic cells within the dilated cavities of the megakaryocytic demarcation membrane system (DMS) and no evidence of phagocytosis. Moreover there was a close relationship between engulfed myeloid cells and the presumptive sites of platelet shedding which had their openings from the cisternal lumina of the DMS. Our results demonstrate that emperipolesis of hematopoietic cells within megakaryocytes should not be regarded as a special nosological feature, but as an indication of enforced thrombocytogenetic activity which is expressed particularly in PTH.     

Modulation of megakaryocyte emperipolesis by phlebotomy: megakaryocytes as a component of marrow-blood barrier

The presence of marrow cells within the cytoplasm of megakaryocytes has been documented and is attributed to the phenomenon of emperipolesis. In a previous study most patients demonstrating this phenomenon had or were suspected of having blood loss. To find out if these are causally related, we induced acute and chronic blood loss in rats and quantitatively measured the emperipolesis index (EI). EI dropped after acute blood loss but rose after chronic blood letting, indicating that blood loss can modulate this phenomenon. In the marrow, megakaryocytes are located preferentially on the abluminal side of sinus endothelium and it is postulated that in the state of heightened demand for cell delivery from marrow into the circulation, some cells take a transmegakaryocytic route to enter the circulation. This concept incorporates megakaryocytes as a component of the marrow-blood barrier.     

Two-way signalling through the LFA-1 lymphocyte adhesion receptor

T lymphocyte recognition of foreign antigens and migration throughout the body require the regulated adhesion of lymphocytes to diverse types of cells and to the extracellular matrix. The lymphocyte adhesion 'receptor' LFA-1, a member of the integrin family, interacts with ICAM-1 and other counter-receptors to mediate adhesion. The LFA-1/ICAM-1 interaction is regulated by signals transmitted from the cytoplasm to the extracellular space. Conversely, LFA-1 transmits signals from the extracellular space to the cytoplasm to regulate T lymphocyte activation. The observed properties of LFA-1 and related adhesion 'receptors' are incorporated into a general model for adhesion during immune surveillance and recognition of foreign antigens.     

Emperipolesis of lymphoid cells by human follicular dendritic cells in vitro.

Isolated follicular dendritic cells (FDCs) showed true and pseudoemperipolesis of fresh tonsillar lymphocytes, even after long-term (50-day) cultivation. Emperipolesis by FDCs was not restricted by allotype specificity, nor was it inhibited by the addition of antibodies against MHC-I & II antigens. Follicular dendritic cells predominantly engulfed B-cells; monocytes and macrophages were not found between FDC cytoplasmic extensions. When highly purified T-cell populations were added to FDC cultures emperipolesis of T-cells occurred, particularly those of the CD4-positive phenotype. Mitoses appeared within 6 h in the emperipolesed lymphocytes and, after an additional 18 h, some lymphocytes exhibited apoptosis.     

Microtubules and filaments in the axons and astrocytes of early postnatal rat optic nerves

Changes in the population of microtubules and filaments within the cytoplasm of maturing axons and astrocytes have been studied during the early postnatal development of rat optic nerves. At birth, all of the axons are unmyelinated; most have a diameter of 0.2–0.3 µ and contain 4–10 microtubules. Neurofilaments do not occur with any frequency until about 5 days postnatal when they appear as individual groups, each containing 4–12. Subsequently, the neurofilaments of each group disperse so that they become more evenly distributed in mature axons. Developing astrocytes show similar but rather more dramatic changes. Most astrocytic processes contain only microtubules at birth, but during maturation filaments begin to appear in increasing numbers while microtubules become less common. This process continues until, in the mature fibrous astrocytes, filaments pack the cytoplasm and microtubules are rare. These observations suggest that the filaments within axons and astrocytes may be formed by the breakdown of microtubules.     

Lymphocyte emperipolesis into autologous monocytes in leukocyte cultures exposed to mitogenic lectins

Lymphocyte-monocyte synergistic interaction in cooperative response to mitogens and antigens is well established. This paper describes a less known--antagonistic (effector-target)--lymphocyte-monocyte interaction that came into existence in a leukocyte culture after the commencement of cellular response to concanavalin A, phytohemagglutinin and Wistaria floribunda mitogen. An invasion of lymphocytes into monocytes and monocyte polykaryons has been found 24-48 h after exposure to mitogens. The invasion is not followed by lysosome fusion with lymphocyte-bearing vacuoles, but is associated with a sequential destruction of the vacuole wall, and eventual disintegration of some affected cells. The expression of pan-T-cell surface antigens, staining patterns for nonspecific esterase and acid phosphatase as well as ultrastructural features show that the lymphocytes entering into and those located within monocytes and polykaryons represent activated T-cells. The presence of developed Golgi complexes associated with coated and smooth vesicles, and lysosomal bodies with microvesicles, tubular arrays or dense cores suggest that these T-cells belong to subpopulations which possess cytolytic activities. The lymphocyte invasion is considered cytolytic emperipolesis directed towards some autologous cells of the mononuclear phagocyte series. Its extent depends upon the mitogen concentration, and density of cell population in the culture. It also shows individual variability. The relationship of cytolytic emperipolesis to phagocytosis, and its possible significance as a mechanism of cell-mediated elimination of undesirable cells is discussed.     

Phagocytosis of bacterial magnetite by leucocytes

Summary Magnetotactic bacteria were introduced into granulocytes and monocytes by phagocytosis. The number of phagocytes containing bacterial magnetites (magneto-sensitive cells) became constant after 1.5 h incubation, and viable phagocytes contained about 20–40 cells of magnetotactic bacteria. Granulocytes and monocytes containing bacterial magnetites were separated by magnet a Samarium-cobalt from lymphocytes. After separation, 89% of lymphocytes were recovered and 95% of the cells were viable. The contamination of phagocytes in the recovered lymphocytes was below 0.8%. Magneto-sensitive granulocytes and monocytes were removed by applying a magnetic field. The nitro-blue tetrazolium-reducing, chemotactic and phagocytic abilities of phagocytes ingesting magnetotactic bacteria were 84%, 88% and 87% respectively after 1 h incubation.     

Modulation of Adhesion Molecule Expression on Rat Cortical Astrocytes During Maturation

Abstract: During development of the vertebrate CNS the functional properties of astrocytes change significantly. Many of these functional changes result from modifications in the expression of cell surface adhesion molecules on astrocytes that mediate the interactions of astrocytes with other astrocytes, neurons, and growing axons. In this study we have compared the cell surface expression of HNK-1, NCAM, and laminin on rat cortical type-I-like astrocytes during maturation in vitro and in vivo. Both the proportion of immunoreactive cells and the relative levels of expression of these antigens on different aged astrocyte populations were assayed by flow cytometry. At birth, most cortical type-I astrocytes express high levels of HNK-1 and NCAM, while ∼50% of the cells express laminin. During maturation in vitro, the proportion of cortical astrocytes that expressed these surface molecules decreased over a period of 28 days, even though cell size and glial fibrillary acidic protein content increased. During maturation in vivo, a qualitatively and temporally similar decrease in antigen expression on astrocytes was observed. This reduction in the expression of specific cell surface molecules on maturing astrocytes results from maturation of a single population of astrocytes and not differential proliferation of a nonexpressing subpopulation of astrocytes, as shown by cell cycle analysis of both immunoreactive and nonimmunoreactive cell populations. These data indicate that during maturation of rat cortical type-I-like astrocytes, the expression of cell surface adhesion molecules is regulated. Furthermore, this regulation appears to be cell autonomous and not dependent on environmental factors. Such regulation of adhesion molecule expression may have profound consequences for the functional properties of astrocytes during CNS maturation.     

Germ cell binding to rat Sertoli cells in vitro

The interaction between male germ cells and Sertoli cells was studied in vitro by co-incubation experiments using isolated rat germ cells and primary cultures of Sertoli cells made germ cell-free by the differential sensitivity of germ cells to hypotonic shock. The germ cell/Sertoli cell interaction was examined morphologically with phase-contrast and scanning electron microscopy and then quantified by measuring radioactivity bound to Sertoli cell cultures after co-incubation with added [3H]leucine-labeled germ cells. Germ cell binding to Sertoli cell cultures was the result of specific adhesion between these two cell types, and several features of this specific adhesion were observed. First, germ cells adhered to Sertoli cell cultures under conditions during which spleen cells and red blood cells did not. Second, germ cells had a greater affinity for Sertoli cell cultures than they had for cultures of testicular peritubular cells or cerebellar astrocytes. Third, germ cells fixed with paraformaldehyde adhered to live Sertoli cultures while similarly fixed spleen cells adhered less tightly. Neither live nor paraformaldehyde-fixed germ cells adhered to fixed Sertoli cell cultures. Fourth, germ cell binding to Sertoli cell cultures was not immediate but increased steadily and approached a maximum at 4 h of co-incubation. Saturation of germ cell binding to Sertoli cell cultures occurred when more than 4200 germ cells were added per mm2 of Sertoli cell culture surface. Finally, germ cell binding to Sertoli cell cultures was eliminated when co-incubation was performed on ice. Based on these observations, we concluded that germ cell adhesion to Sertoli cells was specific, temperature-dependent, and required a viable Sertoli cell but not necessarily a viable germ cell. These results have important implications for understanding the complex interaction between Sertoli cells and germ cells within the seminiferous tubule and in the design of future experiments probing details of this interaction.     

Fine needle aspiration (FNA) cytology of Rosai Dorfman disease

deshpande v and verma k. (1998) Cytopathology 9, 329–335
Fine needle aspiration (FNA) cytology of Rosai Dorfman disease
Rosai Dorfman disease (sinus histiocytosis with massive lymphadenopathy (SHML)) is a benign self-limiting disorder that commonly involves the lymph nodes. We reviewed eight cases of this entity aiming to document the cytomorphological features. Of the eight cases, a preoperative diagnosis was suggested in seven cases. Pertinent features included: numerous large histiocytes with prominent emperipolesis (documented by a halo around the cell), fine vacuoles in the cytoplasm and lymphocytes and plasma cells in the background. In some cases the histiocytes showed atypia. In one biopsy-proven case a diagnosis of Hodgkin's was suggested, emphasizing the pitfalls associated with the FNA diagnosis of this lesion.     

Emperipolesis and interrelations of megakaryocytes and neutrophilic granulocytes in the bone marrow of healthy dogs

Emperipolesis is an ability of one cell to penetrate into cytoplasm of another cell and to stay there for some time, or to pass through it. Unlike a common phagocytosis, not a cell interacting is damaged. Penetration of neutrophilic granulocytes into cytoplasm of megakaryocytes is also considered as emperipolesis, that is revealed in the bone marrow of healthy persons. Its occurrence becomes greater at various pathological states of tumorous and non-tumorous etiology. Histological investigation of the bone marrow of the rib, breast bone, vertebral body and iliac bone crest, performed in 10 healthy dogs makes it possible to state, that there are possible specific interrelations between megakaryocytes and neutrophilic granulocytes, that terminate in death of the former. Therefore, the phenomenon observed cannot be identified with emperipolesis. In this case we, evidently, deal with a morphological demonstration of cell cytotoxicity, when neutrophils, being killers, act as effector-cells, and megakaryocytes - as target-cells. Cell cytotoxicity is a natural phenomenon, that under certain physiological conditions is evidently connected with thrombocytopoiesis.     

Emperipolesis of hematopoietic cells in myelocytic leukemia. Electron microscopic and phase contrast microscopic studies

In case of blast crisis of chronic myelocytic leukemia, the blast cells contained several kinds of normal hematopoietic cells. The peroxidase reaction was strongly positive in the neutrophilic granules of the engulfed neutrophils. These engulfed cells appeared to be normal and the limiting membranes of the engulfing cells seemed to be intact. We speculated therefore that this phenomenon might be emperipolesis. In a case of chronic myelocytic leukemia and a case of acute myelocytic leukemia, some megakaryoblasts showed the same phenomenon. These megakaryoblasts did not phagocytize latex particles. The limiting membranes of the engulfing megakaryoblasts were stained with ruthenium red but those of the engulfed hematopoietic cells were not stained. By phase microscopy, the engulfed cells were actively moving inside the megakaryoblasts and it was observed that the engulfed cells were actually living within the engulfing cells. These results demonstrated that this phenomenon was emperipolesis. Observations with an electron microscope and the phase microscope are indispensable for distinguishing emperipolesis from phagocytosis.