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T Sminia

Publications and source records attributed to T Sminia.

At least 91 records · Page 5Linked to original sources
PubMed1984

Mesenteric lymph nodes: cells with surface and sytoplasmic immunoglobulins.

The distribution and morphology of cells with surface and cytoplasmic immunoglobulins were investigated in mesenteric lymph nodes (MLN) from rats, using both frozen and (fixed) paraffin sections, with a two-step immunoperoxidase technique. Anti-IgA, -IgE, -IgG and -IgM sera were used. Surface Ig-cells (sIg) of all four isotypes studied were found in MLN, mainly localized in the interfollicular area and within the follicle corona. The percentages of sIgA, IgE, IgG and IgM were about 15, 5, 45 and 35%, respectively. In addition, sIgM- and sIgG-cells were found around high endothelial venules. The percentages of cells containing IgA, IgG or IgM (cIg-cells) were about 60, 25 and 15%, respectively; only a few cIgE-cells were found. cIg-cells were not only present in the interfollicular areas and the medulla but also within the germinal centers of the follicles. These results are discussed with regard to the interaction between Peyer's patches (PP) and MLN.

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

Ontogeny of Peyer's patches of the rat.

The development of lymphoid and nonlymphoid cells in Peyer's patches (PP) of the rat was investigated using light microscopical methods (routine histological techniques, enzyme histochemistry and immunohistochemistry). In newborn rats PP were mainly populated by T lymphocytes and Ia-positive nonlymphoid cells, which most likely are interdigitating cells. At about 12 days after birth the B and T cells were localized in defined regions, the follicular (FA) and interfollicular area (IFA), respectively. Compartmentalization within the FA started about 14 days after birth. The first signs of the development of secondary follicles were seen from about 18 days onward. PP obtained their mature structure at about 4 weeks after birth. It is suggested that after PP had developed fully, cells having cytoplasmic IgA migrate via the high endothelial venules (HEV) to the lamina propria of the intestine; cIgM and IgG cells seem to develop locally within the FA.

Animals↗
PubMed1983

Specific antibody formation in mouse spleen. Histology and kinetics of the secondary immune response against HRP.

Specific antibody formation in the spleen was described in mice primed subcutaneously with horseradish peroxidase (HRP) and boosted intravenously with the same antigen. The first specific antibody-forming cells responding to the booster injection were observed after one day in the periarteriolar lymphocyte sheath (PALS). The number and staining intensity of these cells greatly increased subsequently. Between day 3 and 6 after the booster injection a shift was observed in the distribution of antibody-forming cells from the PALS to both the site of entry of the central artery in the PALS and the site where the blood passes via terminal arterioles to the red pulp. Specific antibody-forming cells became highly concentrated in these areas, which constitute the so-called marginal zone bridging channels. After day 6 the number of antibody-forming cells decreased sharply. On the basis of this distribution pattern it was suggested that after subcutaneous priming and intravenous boosting specific antibody-forming cells migrate from the popliteal lymph nodes to the spleen and gradually leave the spleen at later stages of the response. Specific antibody-forming cells did not occur in the germinal centers during any stage of the response.

Animals↗
PubMed1983

Specificity and memory in increased defence reactions against bacteria in the pond snail Lymnaea stagnalis.

In Lymnaea stagnalis injections with dead Escherichia coli or Staphylococcus saprophyticus bacteria resulted in an enhanced clearance of both live S. saprophyticus and E. coli injected 4 days later. A non-specific activation of the internal defence system was concluded from these findings. The activation was dose-dependent: pre-injections with high doses resulted in a higher increase in the clearance capacity of the snails than pre-injections with low doses of bacteria. The state of increased activity of the defence system, induced with injection of dead E. coli, lasted at least 64 days. The heightened responses of the defence system were probably due to an activation of the blood cells (amoebocytes) since: 1) amoebocyte numbers increased faster in bacteria pretreated snails than in control animals; 2) ultrastructural observations revealed that the amoebocytes of bacteria pre-treated animals had a more ruffled outline than those of control snails; 3) amoebocytes from sensitized snails showed a higher phagocytic activity in vitro; 4) mitotic activity of amoebocytes increased after snails had been injected with bacteria.

Animals↗
PubMed1983

Characterization of non-lymphoid cells in Peyer's patches of the rat.

The aim of the present study was to correlate in vitro and in situ observations on nonlymphoid cells in Peyer's patches (PP) of the rat. By carrying out enzyme cytochemical reactions (acid phosphatase, APh, and non-specific esterase, NSE) and immunocytochemistry (Ia antigen staining) on cell suspensions and cryostat sections of PP, two classes of nonlymphoid cells could be distinguished. These were (1) strongly APh- and NSE-positive cells without or with a slight Ia membrane staining and (2) strongly Ia-positive cells with a weak APh and NSE activity. The first cell class comprised the classical macrophages which, except for tingible body macrophages, were glass-adherent. The second cell class was non-adherent and comprised dendritic (interdigitating) cells. The role of this Ia-positive non-adherent cell population was discussed, and a hypothesis was presented on the relation between mononuclear blood cells, veiled cells, and interdigitating cells in PP.

Acid Phosphatase↗
PubMed1983

Large mononuclear Ia-positive veiled cells in Peyer's patches. II. Localization in rat Peyer's patches.

Dendritic Ia-positive veiled cells were seen in frozen sections of rat Peyer's patches within the lymphoepithelium, in the reticular area just underneath and in the T-dependent interfollicular area. From immunohistochemical stainings with anti-IgA, IgE, IgG, IgM and monoclonal anti T lymphocyte sera it is concluded that these Ia-positive cells do not belong to lymphocyte series. The ultrastructure of these Ia-positive veiled cells resembled the morphology of the veiled cells found in Peyer's patch cell suspensions and in skin lymph. It is suggested that these cells form an antigen presenting cell system in mucosa-associated lymphoid tissue, similar to the antigen presenting cell system in the skin.

Animals↗
PubMed1983

Ontogeny of non-lymphoid and lymphoid cells in the rat gut with special reference to large mononuclear Ia-positive dendritic cells.

The ontogeny of rat Peyer's patches was studied with special reference to Ia-positive dendritic cells. The 16-day-old foetus contained large Ia-positive dendritic cells randomly distributed throughout the gut wall and mesentery. In cell suspensions prepared from the foetal gut, these cells showed the typical movement pattern of veiled cells, and they shared ultrastructural features with these and other antigen-presenting cells. The gut was found to be the first organ in which large numbers of these Ia-positive dendritic cells were found. At 16 days gestation, the Ia-positive dendritic cells were randomly distributed throughout the primitive gut wall, but at later stages accumulated in structures which were clearly recognizable as Peyer's patches from 20 days gestation onwards. T and B lymphocytes could be seen on the day of birth at the earliest, at first randomly distributed throughout the Peyer's patch, but afterwards concentrating in separate T- and B-cell regions. Two weeks after birth Peyer's patches consisted of densely populated B-cell nodules, mainly comprising surface IgM (sIgM) positive cells, and internodular T-cell regions. Ia-positive dendritic cells were situated between the epithelial cells of the dome area, just underneath this epithelium in a loose reticular area and in the internodular T-cell regions. These Ia-positive dendritic cells were acid phosphatase negative or only weakly positive. Some Ia-positive dendritic cells were also present in small intestinal villi at all ages studied. However, these cells started to express an increasing acid phosphatase activity in the 2 weeks following birth. Thus they resemble macrophages, while Peyer's patch dendritic cells show characteristics of antigen-presenting cells.

Animals↗
PubMed1983

Histological observations on the intestinal immune response towards horseradish peroxidase in rats.

The intestine immune response in rats following immunization with horseradish peroxidase (HRP) was studied morphologically. Various routes of immunization (intraperitoneal, intravenous, intraenteric and intra-Peyer's patch) were tested. Single injections did not evoke any specific antibody-containing (anti-HRP) cells in Peyers' patches (PP) and lamina propria of the small intestine. Only an intraperitoneal or intraenteric booster injection following intraperitoneal priming induced the formation of anti-HRP cells in PP and lamina propria. In the initial period of the immune response most of the anti-HRP cells were blast cells which were located mainly within the thymus-dependent interfollicular area of PP. Later on in the immune response more than 90% of the anti-HRP cells were located in the lamina propria of the villi and had the morphology of plasma cells.

Animals↗
PubMed1983

Cytophilic receptors for foreignness and some factors which influence phagocytosis by invertebrate leucocytes: in vitro phagocytosis by amoebocytes of the snail Lymnaea stagnalis.

By means of in vitro phagocytosis it was demonstrated that macrophage-like blood cells of an invertebrate (amoebocytes of the pond snail Lymnaea stagnalis) possess cytophilic receptors for foreignness. These receptors are lectin molecules which are reversibly bound to the surface of the cells. Phagocytosis is dependent, beyond recognition of foreignness, on temperature and pH, and on the feeding condition of the snails.

Agglutinins↗
PubMed1982

Distribution of IgM- and IgG-containing cells during the primary immune response in the rat spleen.

The morphology and localisation of IgM- and IgG-containing cells in the spleen of rats immunized with sheep red-blood cells (SRBC) were studied by combining immunohistochemical reactions with routine histological and histochemical methods. It was shown that IgM cells occur only in the outer periarteriolar lymphocyte sheath (PALS), whereas IgG cells are present throughout the whole PALS. It has been concluded that these cell types have different routes of migration. Both IgM- and IgG-containing cells were found in the germinal center in close relation with the extracellular immune complexes. The significance of this localisation is discussed.

Animals↗
PubMed1982

An immunohistochemical study of cells with surface and cytoplasmic immunoglobulins in situ in Peyer's patches and lamina propria of rat small intestine.

The distribution of cells with surface and cytoplasmic immunoglobulins was studied in Peyer's patches (PP) and intestine of rats, using both frozen and paraffin sections, with a two-step peroxidase technique. Anti IgM, IgG, IgA and IgE sera were used. Surface staining was found within PP with all antisera used. Although the villi contained predominantly IgA plasma cells (PC), IgG PC and a few IgM and IgE PC were also found. Within PP, however, no IgA PC were found but IgM and IgG PC were present in all stages of development, mainly in the dome. PC of all types, but mostly IgA cells, were present in and around high endothelial venules (HEV). The results suggest that IgM and IgG PC precursors can develop to PC within PP whereas IgA precursors do not. PC appear to home to the gut preferentially via HEV.

Animals↗
PubMed1982

Antigen-trapping cells in Peyer's patches of the rat.

Peyer's patches (PP) of rats were studied with immunocytochemical, enzyme cytochemical, and electron microscopic techniques. Special attention was paid to the non-lymphoid antigen-trapping cells. Follicular dendritic cells, morphologically comparable to those present in spleen and lymph nodes, were found in the germinal centers of PP. Ia-positive cells with the morphological characteristics of interdigitating cells were seen in the interfollicular area. Thus, both types of antigen-presenting cells, characteristic for B- and T-cell areas, respectively, were present in PP.

Animals↗
PubMed1982

Peroxidase-positive blood cells in snails.

The present study deals with phagocytic blood cells of 3 species of freshwater snails and one terrestrial snail species. Histochemical tests on peroxidase indicate that the blood cells of the freshwater snails have high peroxidase contents, whereas those of the terrestrial snail do not contain this enzyme. Peroxidases were not only present in the lysosomal system but also in the RER and Golgi apparatus. It appears that the phagocytic blood cells of freshwater snails are able to synthesize peroxidase.

Animals↗
PubMed1981

Immunocytochemical demonstration of a humoral defense factor in blood cells (Amoebocytes) of the pond snail, Lymnaea stagnalis.

Monolayers of blood cells (amoebocytes) and sections of connective tissue and of amoebocyte pellets of the freshwater pulmonate gastropod Lymnaea stagnalis were stained immunocytochemically with antisera to snail agglutinin/opsonin. The presence of this substance was demonstrated light microscopically both in the cytoplasm and on the cell membrane of amoebocytes. This suggests that amoebocytes synthesize agglutinin/opsonin, and bear it at their surface as receptors for foreign materials.

Agglutinins↗