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E C Hoefsmit

Publications and source records attributed to E C Hoefsmit.

At least 55 records · Page 3Linked to original sources
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↗
PubMed1985

False localization of acid phosphatase activity in the nuclear envelope and endoplasmic reticulum of peritoneal macrophages.

Acid phosphatase cytochemistry using lead salt methods was performed on rat peritoneal macrophages obtained by the intraperitoneal injection of dextran five days previously. Lead precipitate was present in the nuclear envelope, the rough endoplasmic reticulum, Golgi apparatus and lysosomes in about 50% of these cells. The formation of reaction product appeared to be substrate-specific and was sensitive to sodium fluoride in all these sites. However, only in the nuclear envelope, the rough endoplasmic reticulum and Golgi apparatus could lead salt precipitation be prevented by (a) omission of the washing procedure following the incubation step, (b) postincubation in a medium containing sodium fluoride, or (c) washing in buffer containing lead salt. It is concluded that precipitation of lead salt does not prove the presence of acid phosphatase activity in these organelles. The formation of precipitate in these sites is probably due to a local matrix effect, facilitated by the persistence of acid phosphatase activity in the lysosomes and a suboptimal trapping efficiency of phosphate ions during the washing procedure which follows in the incubation step.

Acid Phosphatase↗
PubMed1984

Lymph node accessory cells in the immune response. The primary response to paratyphoid vaccine in rat parathymic lymph nodes.

The immune response in the rat parathymic lymph node was studied after administration of antigen into the peritoneal cavity. Special attention was paid to the accessory cells, which might induce the response. During the induction phase of the response a heterogeneous population of non-lymphoid mononuclear cells was present in the subcapsular sinus and the cortex of the node. These cells resemble "veiled cells" described in skin draining lymph and interdigitating cells in the paracortex of skin draining lymph nodes, but they do not contain Birbeck granules. It is concluded that the appearance of these granules depends on the site of the exudate provocation and that the presence of the organelles in these accessory cells is not obligatory for lymphocyte stimulation.

Animals↗
PubMed1984

Ontogeny of the rat thymus micro-environment: development of the interdigitating cell and macrophage populations.

The ontogeny of the rat thymus micro-environment and in particular the development of the interdigitating cell (IDC) and macrophage (M phi) populations has been studied. At day 15 of fetal life the thymus consisted of an epithelial primordium in which some Thy-1 positive thymocytes were present around local capillaries in a central area. At day 16 some Ia positive cells, which could not be further identified, and some monocyte-like M phi were observed in the central area. From day 17 the thymus became lobulated by ingrowth of small blood vessels with perivascular connective tissue from the surrounding capsule. An Ia positive epithelial reticulum developed which became populated by increasing numbers of thymocytes. Some strongly acid phosphatase positive M phi were present from this stage of development. From day 19 cortical and medullary areas could be distinguished in the thymus. The cortex consisted of an Ia positive epithelial reticulum in which closely packed thymocytes and scattered M phi were present. The medulla demonstrated a confluent Ia staining and consisted of an epithelial reticulum in which thymocytes, strongly non-specific esterase positive IDC and an occasional M phi were present. Also highly phagocytic IDC-like cells were observed in the medulla, most likely they comprise the population of differentiating IDC. Thymocyte proliferation areas, which were strongly pyroninophilic, were observed from day 21 in the cortex, just beneath the surrounding connective tissue capsule. A distinct cortico-medullary region with many M phi was present one week after birth. From this stage the IDC and M phi distribution was comparable with older thymi.

Acid Phosphatase↗
PubMed1984

Ontogeny of the rat thymus micro-environment: development of the interdigitating cell and macrophage populations.

The ontogeny of the rat thymus micro-environment and in particular the development of the interdigitating cell (IDC) and macrophage (M phi) populations has been studied. At day 15 of fetal life the thymus consisted of an epithelial primordium in which some Thy-1 positive thymocytes were present around local capillaries in a central area. At day 16 some Ia positive cells, which could not be further identified, and some monocyte-like M phi were observed in the central area. From day 17 the thymus became lobulated by ingrowth of small blood vessels with perivascular connective tissue from the surrounding capsule. An Ia positive epithelial reticulum developed which became populated by increasing numbers of thymocytes. Some strongly acid phosphatase positive M phi were present from this stage of development. From day 19 cortical and medullary areas could be distinguished in the thymus. The cortex consisted of an Ia positive epithelial reticulum in which closely packed thymocytes and scattered M phi were present. The medulla demonstrated a confluent Ia staining and consisted of an epithelial reticulum in which thymocytes, strongly non-specific esterase positive IDC and an occasional M phi were present. Also highly phagocytic IDC-like cells were observed in the medulla, most likely they comprise the population of differentiating IDC. Thymocyte proliferation areas, which were strongly pyroninophilic, were observed from day 21 in the cortex, just beneath the surrounding connective tissue capsule. A distinct cortico-medullary region with many M phi was present one week after birth. From this stage the IDC and M phi distribution was comparable with older thymi.

Age Factors↗
PubMed1983

Characterization of the population of phagocytic cells in thymic cell suspensions. A morphological and cytochemical study.

Rat thymic phagocytic cells were characterized in vitro using various light- and electron-microscopical techniques. Thymic cell suspensions were mechanically prepared and enriched for non-lymphoid cells, which were predominantly phagocytic and of three types. Type I showed acid phosphatase (APh) activity in small granules dispersed throughout the cytoplasm and were mostly Ia antigen-positive, although the Ia membrane label varied in intensity and distribution among individual cells. Only a few cells had endogenous peroxidase activity. The type-I cells could not be clearly distinguished morphologically from type-II or -III cells, and most likely comprise precursors of both these cell types. Type-II were large pale cells with many slender cell processes. These cells had APh activity centrally positioned, were strongly positive for Ia on the cell membrane and were negative for endogenous peroxidase. The cytoplasm frequently contained Birbeck granules, which unequivocally classifies these cells as the in vitro equivalent of the interdigitating cells present in the medullary area of the thymus in situ. Type-III cells were rounded with a smooth or ruffled cell membrane and contained vacuoles and many phagolysosomes. They were strongly positive for APh which was present throughout the cytoplasm. About 50% of these cells were positive for endogenous peroxidase in a pattern resembling resident macrophages. The cells were negative for Ia antigens. Type-III cells mostly likely represent the macrophages found in the cortical area of the thymus.

Acid Phosphatase↗