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Biomedical subjects

E C Hoefsmit

Publications and source records attributed to E C Hoefsmit.

At least 19 recordsLinked to original sources
PubMed1992

Differential effect of cyclosporin application on epithelial cells of the rat thymus. Immunohistochemical study.

Young adult male Wistar rats were given 30 mg per kg of cyclosporin (CS) for 21 consecutive days. A panel of monoclonal antibodies was used to study the phenotype of thymic epithelial cells. After treatment with CS, subcapsular epithelial cells, although phenotypically similar to medullary epithelial cells, were changed in a similar manner to phenotypically distinct epithelial cells of the deep cortex. These cells became enlarged, stockier and their cytoplasmic prolongations were thicker and coarser compared with control cells and their number was not decreased. In contrast, the number of medullary epithelial cells was markedly reduced, whereby the cells with the most mature phenotype (CK8+10-19- and CK8+10+19-) were the most prominently depleted. No proliferation of thymic epithelial cells was detected as monitored by incorporation of 5-bromodeoxyuridine.

Animals↗
PubMed1992

Effect of Bacillus Calmette-Guérin inoculation on numbers of dendritic cells in bronchoalveolar lavages of rats.

Dendritic cells (DC) are present in all lymphoid tissues and are widely distributed in the airway epithelium and lung parenchyma. In this study DC were morphologically and cytochemically identified in normal rat bronchoalveolar lavage (BAL), although in very low percentages. Furthermore, the total population as well as different Percoll density fractions demonstrated poor antigen-presenting capacity and even suppressed antigen-specific stimulation by rat splenic DC. In contrast, when an inflammatory response was induced by intratracheal inoculation of Bacillus Calmette-Guérin (BCG), an increase of Ia-positive cells, containing high percentages of monocytes and DC (MDC) was found. In BAL, DC increased about 25 times within 48 h after BCG inoculation. These BCG-induced BAL cells as well as the different density fractions showed a high antigen-presenting capacity at low concentrations. However, at higher concentrations they were suppressive, except for the highest density fraction which lacked alveolar macrophages (AM). These results indicate that the increased numbers of Ia-positive MDC during an inflammatory reaction are very likely responsible for antigen presentation in vitro. In contrast, AM suppress the antigen-specific T cell proliferation in a concentration dependent manner.

Animals↗
PubMed1991

A combined method for both endogenous myeloperoxidase and acid phosphatase cytochemistry as well as immunoperoxidase surface labelling discriminating human peripheral blood-derived dendritic cells and monocytes.

On light microscopical (LM) level dendritic cells (DC) isolated from lymphoid organs can be discriminated from macrophages (M phi) by the presence of acid phosphatase (APh) activity in a spot near the nucleus and constitutional expression of class II antigens. The aim of our study was to investigate whether DC and monocytes (Mo) enriched from human peripheral blood could be discriminated on the electron microscopical (EM) level. Therefore we developed a triple method by which we compared the presence of myeloperoxidase (MPO) containing vesicles, the localization of APh containing vesicles and expression of MHC class II and RFD1 (a DC-associated class II-like antigen) plasma-membrane antigens. DC, functionally characterized as potent stimulators in a MLR, are MPO-negative, whereas Mo show MPO in cytoplasmic granules. Although both DC and Mo show little APh activity at LM level, both types of cells show APh activity at the EM level but at different locations. In DC APh containing vesicles are present in a distinct juxtanuclear area, in contrast to Mo, which show APh activity in lysosomes scattered throughout the whole cytoplasm. Moreover, on both LM and EM level, DC are strongly class II positive, whereas Mo show variable labelling intensity for class II, while RFD1 was only found on DC.

Acid Phosphatase↗
PubMed1991

Langerhans cells in nasal mucosa of patients with grass pollen allergy.

Langerhans cells (LC) are known to be present in squamous epithelia of the human body. They are dendritic cells (DC) and characterized by the presence of Birbeck granules (BG). In previous studies, DC positive for CD1a and HLA-DR were found in the cylindrical epithelium and the lamina propria of the nasal mucosa. In our study, more CD1a cells occurred in the allergic patients than in the non-allergic controls. In a combined light microscopy (LM) and electron microscopy (EM) study, biopsies of nasal mucosa in allergic patients were studied. We used monoclonal antibodies against CD1a and HLA-DR, to identify DC in LM cryostat sections. The presence of BG identified most of the intra-epithelial DC as LC on the EM level, whereas a minority of DC in the lamina propria also contained BG. The ultrastructure of LC and DC in the ciliated cylindrical epithelium and the lamina propria is compared.

Adult↗
PubMed1991

Localization of class II molecules in storage vesicles, endosomes and lysosomes in human dendritic cells.

Class II molecules are a prerequisite for antigen presentation. We studied whether class II molecules can be found in the endocytic and/or lysosomal route of dendritic cells (DC), which are very potent antigen-presenting cells. Therefore first immunolabelling for HLA-DR alpha chain was applied on ultrathin cryosections of cells of which plasma membrane HLA-DR/DQ molecules were labelled in suspension, followed by incubation with the endocytic marker BSA-gold. Second, immunolabelling for HLA-DR alpha chains was applied on ultrathin cryosections of cells on which enzyme cytochemistry for acid phosphatase (APh) was performed to see whether the class II positive vesicles belong to the lysosomal compartment. Third, this immunolabelling was applied on cryosections of cells pretreated with the protein synthesis inhibitor cycloheximide (CHX) to see whether the class II positive vesicles are derived from biosynthesis. We found limited uptake of BSA-gold into endosomes and lysosomes, some of which also contained endocytozed HLA-DR/DQ. APh and HLA-DR were observed in the same vesicles but also vesicles containing either HLA-DR or APh were found. However, many class II positive vesicles were found, which were apparently not accessible to exogenous molecules. Moreover, the amount of class II positive vesicles decreased after treatment of the cells with CHX, suggesting that these vesicles form part of the biosynthetic route. These results imply that there is a cluster of class II positive vesicles, probably a storage compartment, that has connections with the lysosomal system. The concentration of lysosomes and class II positive vesicles in the juxtanuclear area of DC is probably of crucial importance in the processing of antigens.

Alkaline Phosphatase↗
PubMed1991

Localization of pepsinogen (A and C) and cellular differentiation of pepsinogen-synthesizing cells in the human gastric mucosa.

The localization of pepsinogens (PG A and PG C) was studied intracellularly in human gastric biopsies embedded in Lowicryl K4M, using affinity-purified antibodies and protein A-gold. The homogeneous secretory granules of the chief cells contained both PG A and PG C, as was proved by serial sections. Identical reaction was also seen in the core of the biphasic mucous neck cell granules, whereas the mantle did not label. The rough endoplasmic reticulum (RER) and Golgi complex of the chief cells and mucous neck cells contained ample label. Transitional cells identified by the presence of granules of both chief cells and mucous neck cells were recognized. This type of mucous neck cell is thought to transform into a chief cell. However, an increase of RER that could explain an increase of the pepsinogen production was not observed. A mixture of these granules was also found in cells morphologically characterized as young parietal cells, suggesting a common precursor for these three cell types. These observations make the transformation from mucous neck to chief cells questionable. Antral gland cells contained only PG C, as was shown in serial section, too.

Cell Differentiation↗
PubMed1990

Human peripheral blood dendritic cells concentrate in contrast to monocytes intracellular HLA class II molecules in a juxtanuclear position.

The localization of histocompatibility antigens of the HLA-D locus in dendritic cells (DC) and monocytes (Mo) isolated from human peripheral blood was investigated. Functionally DC were characterized by their capacity to act as strong stimulators in an allogeneic mixed leucocyte reaction. In cytospins, DC were differentiated from Mo by dendritic morphology, strong HLA class II and moderate RFD1 expression on the plasma membrane and acid phosphatase activity in a juxtanuclear spot. Ultrathin cryosections showed that DC had a heavily labelled plasma membrane for HLA-D. In addition, these antigens were found in intracellular vesicles predominantly located in the juxtanuclear zone. This pattern of labelling was not seen in Mo. Obviously, DC concentrate intracellular class II antigens in the same area as lysosomal activity. These results may indicate that this juxtanuclear area is a center of antigen processing in DC.

Acid Phosphatase↗
PubMed1990

The Langerhans cell: an underestimated cell in atopic disease.

Langerhans cells (LC) are very potent antigen-presenting cells. In atopic disorders such as allergic rhinitis and atopic dermatitis LC are known to bear IgE surface molecules. IgE-positive LC can bind allergen and present it to T lymphocytes to induce an allergen-specific T-cell response and IgE synthesis. Therefore, IgE-bearing LC might play an important role in the triggering of the immune system to maintain ongoing IgE synthesis. The importance of the IgE-bearing LC in atopy has not been assessed but deserves further investigation to find out more about the part played by these cells, not only in the atopic disorders described here but also in others such as gastrointestinal allergy and allergic asthma.

Dermatitis, Atopic↗
PubMed1988

Distinct subpopulations of elicited human macrophages in peritoneal dialysis patients and women undergoing laparoscopy: a study on peroxidatic activity.

The endogenous peroxidatic activity (PA) pattern of peritoneal macrophages from 24 continuous ambulatory peritoneal dialysis (CAPD) patients and from five healthy women undergoing laparoscopy was studied. In general, the macrophages showed two different PA patterns in vivo: exudate and negative macrophages. However, two of 24 CAPD patients showed resident macrophages, the first described in vivo in man. Since, in general, the examined human peritoneal macrophages are exudate and PA-negative, this suggests, in accordance with the animal model system, that a chronic sterile inflammation exists in the peritoneal cavity of CAPD patients and healthy women undergoing laparoscopy. After 2 hr culture, blood monocytes and peritoneal macrophages transformed into cells with the characteristics of exudate-resident and resident macrophages, so isolation procedures that include short periods of culture can change the developmental stage of human monocytes and macrophages.

Female↗
PubMed1986

Phosphatase cytochemistry with cerium as trapping agent. Verification of acid phosphatase and glucose-6-phosphatase reactive sites.

Lead is prevalently replaced by cerium as trapping agent in phosphatase cytochemistry to prevent non-specific precipitation. Recently, substrate specific but artefactual lead precipitates have been described in the nuclear envelope (NE) and rough endoplasmic reticulum (RER) due to a local matrix effect. In the present study a verification was carried out of the localization of acid phosphatase and glucose-6-phosphatase in the NE and RER of rat peritoneal macrophages and hepatocytes respectively with cerium. It appeared that precipitates of cerium phosphate in NE and RER of peritoneal macrophages do not represent sites of acid phosphatase activity but are due to the matrix effect. However, in rat hepatocytes these organelles demonstrate true reactive sites for glucose-6-phosphatase.

Acid Phosphatase↗
PubMed1986

Light microscopical detection of single 5 and 20 nm gold particles used for immunolabelling of plasma membrane antigens with silver enhancement and reflection contrast.

To detect plasma membrane antigens, cytocentrifuge preparations of the macrophage-like cell line P388D1 were incubated with monoclonal antibodies and labelled with 5 and 20 nm gold particles conjugated to immunoglobulins or protein A. The 20 nm, but not the 5 nm, particles could be observed by reflection-contrast light microscopy. Single 5 nm particles, however, were clearly demonstrable with silver contrast enhancement, both in absorption contrast and in reflection contrast. The method proved to be compatible with cytochemical methods such as acid phosphatase.

Animals↗
PubMed1986

The development of the resident pattern of endogenous peroxidatic activity in mouse peritoneal macrophages coincides with the expression of the differentiation antigen F4/80. A combined method for immunoperoxidase labeling and endogenous peroxidase cytochemistry.

In the mouse the maturation of mononuclear phagocytes was followed by comparing the ultrastructural pattern of endogenous peroxidatic activity (PA) at different time points during an acute peritonitis induced with newborn calf serum (NCS). Exudate macrophages demonstrate PA only in lysosomes, whereas resident macrophages have reaction product in the nuclear envelope (NE) and rough endoplasmic reticulum (RER). Transitional cells called "exudate-resident" macrophages have PA in the NE, RER, and some virginal lysosomes. In addition, peroxidase-negative macrophages were also present. A monoclonal antibody, F4/80, that specifically recognizes a mouse macrophage differentiation antigen (Austyn and Gordon, 1981) was used in this study. To compare the indirect immunoperoxidase labeling of this antigen and the endogenous peroxidase cytochemistry on the cellular level, a combined method was developed. Finally, the method was applied to the peritoneal cells at different time points after intraperitoneal injection of NCS in mice. The relative numbers of cells demonstrating the different patterns of endogenous PA and the proportions of each subpopulation expressing F4/80 antigen were estimated. It appeared that the expression of the antigen F4/80 coincides with the development of the resident pattern of PA. It is therefore concluded that the macrophages with the resident pattern of endogenous peroxidase are derived from monocyte-like exudate macrophages. In addition, the results indicate that both exudate-resident macrophages and at least a part of the peroxidase-negative macrophages are transitional forms.

Animals↗
PubMed1985

Characterization of dendritic cells, isolated from normal and stimulated lymph nodes of the rat.

Non-lymphoid dendritic cells were isolated from normal and paratyphoid vaccine-stimulated lymph nodes draining the rat skin. They were studied using enzymecytochemical, immunocytochemical and electron-microscopical methods. These cells had an irregular outline and an eccentrically situated nucleus. All showed acid phosphatase activity in a central area and expressed Ia antigen on the plasma membrane. Birbeck granules were exclusively present in dendritic cells isolated from lymph nodes in the induction phase of the immune response. This observation concurs with the presence of Birbeck granules in interdigitating cells in situ during the same period of the immune response. It is concluded that the dendritic cells are the in-vitro equivalents of the non-actively phagocytizing population of interdigitating cells.

Acid Phosphatase↗