The migration of lymphocyte subsets from blood to lymph in the normal rat.
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Animals↗
Biomedical subjects
R Pabst
Publications and source records attributed to R Pabst.
The physiological role of the lung in lymphocyte migration.
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Animals↗
Lymphocyte emigration from the ovine thymus: characterization of lymphatic emigrants and venous emigrants.
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Animals↗
Regeneration of autotransplanted lymph node fragments.
In normal young minipigs thin slices of autologous mesenteric or superficial inguinal lymph nodes were implanted either in the greater omentum or subcutaneously in the groin region. The regeneration was studied histologically and connections between the afferent lymphatics and the regenerated tissue were checked. In the greater omentum, no regenerated lymph node tissue was found. In the inguinal region, lymphoid tissue with all the typical lymph node compartments was identified following antigenic stimulation in the draining area. Sinuses, germinal centres with a lymphatic corona, and a paracortex with typical high endothelial venules were seen. There was evidence of afferent lymphatics, e.g., macroscopically visible lymphatics, the occurrence of a subcutaneously injected dye, the effect of antigenic stimulation and a normal lymph node structure. Avascular transplants of autologous lymph node fragments regenerate subcutaneously, possibly providing a future technique for treating lymphoedema after radical excision or irradiation of lymph nodes.
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Immunoarchitecture of regenerated splenic transplants: influence of donor and host age on the regeneration of splenic compartments.
Inbred rats were used as a model to determine the influence of the age of the implanted splenic tissue and the age of the host on the structure of transplanted splenic tissue. Monoclonal antibodies against lymphocyte, macrophage and dendritic cell subsets were used to evaluate the different compartments of the spleen. Adult rats received implants from adult, weanling or fetal rats, weanling rats received splenic tissue from adult, weanling or fetal rats and neonatal rats received neonatal or fetal spleens. There were major differences in the structure and cellular composition of the regenerated splenic tissue. The younger the recipients and the donor spleens, the better the normalization of the splenic compartments and the less fibrous tissue was found 3 months after transplantation. The follicles regenerated in all transplants, but the marginal zone was only normally developed in wealing and neonatal hosts. The periarteriolar lymphatic sheath regenerated in a similar manner to the marginal zone. Whenever a compartment developed, its cellular composition was the same as in a normal spleen. The immunohistological techniques enabled splenic regeneration to be characterized revealing a far from normal histological splenic structure in many age groups. These findings suggest that splenic regeneration in children might result in splenic tissue with normal compartments, which would be in contrast to some data in adults.
Aging↗
Malaria infection in rats with stimulated splenic red pulp: the blood flow and protective effect in normal and transplanted splenic tissue.
After splenic autotransplantation both weight and blood flow of the regenerated splenic tissue are decreased. In addition, the protective function of the transplant is less compared to that of the normal spleen. In the present study, the red pulp of normal and transplanted splenic tissue was stimulated by injections of phenylhydrazine to increase the weight, the blood flow, and the protective function. After stimulation, the weight of the normal spleen increased to 900 +/- 70 mg (control 530 +/- 20 mg) and the transplanted tissue to 240 +/- 70 mg (control 70 +/- 20 mg). This enlargement was caused by an increase in the splenic red pulp. However, the relative blood flow decreased in both the normal spleen and the transplant to 50% of the normal value. To evaluate the protective function of the stimulated splenic tissue, normal, splenectomized and transplanted rats were infected with Plasmodium berghei. Despite the dramatic increase in the red pulp, neither the normal nor the transplanted animals showed a survival rate superior to that of the splenectomized animals. The mass of splenic tissue obviously does not correlate with the protective effect of the spleen in parasitic infections.
Animals↗
The spleen in lymphocyte migration.
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Animals↗
Influence of donor and host age on the regeneration and blood flow of splenic transplants.
After splenectomy there is an increased risk of fatal overwhelming postsplenectomy sepsis, especially in children. If all alternatives to splenectomy fail, autotransplantation of splenic fragments is indicated. These fragments regenerate after a necrotic phase to small splenic nodules. Regulatory factors governing the regeneration process are largely unknown. Inbred rats were used as a model to define the influence of recipient and donor age on the regenerated mass and the blood flow of transplanted splenic fragments. These are both important factors for the protective function of the spleen. Fetal, newborn, weanling, or adult spleens were implanted into the greater omentum of newborn, weanling, or adult rats. The younger the recipient and donor, the better the regeneration and perfusion of transplants. However, these did not reach more than 40% of the normal splenic mass. In addition, no experimental group achieved more than one third of the normal splenic blood flow. There is an obvious age dependency in splenic regeneration and blood flow, but the transplants are far from attaining a normal splenic mass and perfusion.
Age Factors↗
Blood transit and recirculation kinetics of lymphocyte subsets in normal rats.
Thoracic duct lymphocytes (TDL) were labelled with fluorescein isothiocyanate (FITC) and injected into normal, unanaesthetized rats with either a central venous catheter or a thoracic duct cannula. The blood transit time and the appearance in the lymph was calculated and then the percentages of B, T, T helper, and T suppressor lymphocytes were determined with monoclonal antibodies (Ox12, Ox19, W3/25, and Ox8, respectively). The blood transit time of all subsets was about 30 min. However, the percentage of B lymphocytes from 5 min after injection onwards is reduced (14.5 +/- 1.9%) compared to the injected TDL (32.7 +/- 1.7%). These cells are not in the lung vascular pool. The recovery of FITC-labelled TDL in the thoracic duct within 48 h is much higher (56.8 +/- 5.3% of the injected lymphocytes) than in previous studies using radioactive markers. B lymphocytes appear later and in a reduced number in the thoracic duct. The mean transit time is 26 h and the recovery 31.5 +/- 4.2% in contrast to T lymphocytes (18 h and 66.3 +/- 6.5%, respectively). The technique of combining FITC in vitro labelling with surface staining after completion of migration does not interfere with lymphocyte migration. It can therefore be used to study the migration of lymphocyte subsets in normal, untreated animals.
Animals↗
Subpopulations of T lymphocytes emigrating in venous blood draining pig thymus labelled in vivo with fluorochrome.
The emigration of labelled thymus cells in the pig was studied directly in blood draining the large right distal cervical lobe of the thymus after controlled labelling with FITC delivered through cannulated branches of a main thymic artery and vein by temporary ex vivo perfusion at body temperature. Roughly 1% of thymic cells emigrated per day. Unlike most thymocytes, which are small, the size spectrum of thymic emigrants is slightly larger than that of typical blood lymphocytes. Surface-marker studies show that the surface phenotypes of the emigrants differ from both typical thymus and peripheral blood lymphocytes. Although the emigrants resemble thymocytes in the high proportion of strong rosettes formed with sheep red blood cells (RBC), they rosette poorly with pig red cells, particularly in the unenhanced saline test, in this respect behaving like blood lymphocytes. The peripheral T-cell subset bearing a Fc receptor is almost absent in thymus, but is well represented among the emigrants which thus resemble corticosteroid-resistant thymocytes in the pig. The large population of thymus-dependent Null lymphocytes in young pig blood apparently arise in thymus since they constitute 1/3 of emigrants, although only forming less than 10% of thymus cells. This emigration of thymic cells is discussed in relation to its implications for the turnover of known functional peripheral T-cell populations.
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Postnatal development and lymphocyte production of jejunal and ileal Peyer's patches in normal and gnotobiotic pigs.
The development of the number, size, structure and proliferative capacity of Peyer's patches (PP) in the jejunum and ileum has been studied during the early postnatal period of conventional and germ-free pigs. A mean of 15 discrete PP in the jejunum and upper ileum (jejPP) were counted at birth, and the number increased only gradually. A continuous PP is located in the terminal ileum (ileal PP). The length of both jejPP and ileal PP increased with age due to the increase in follicle size and in the number of follicles in the ileal PP. In older pigs, only the ileal PP regressed to small scattered follicles. In germ-free piglets at 39 and 59 days of age, longer PP were found than in normal new-born piglets, but they were significantly shorter than in age-matched controls. Lymphocyte production was studied by the metaphase-arrest technique using vincristine. Lymphocyte production in follicles increased dramatically with age, while in other compartments, such as the inter-follicular and dome area, a low age-independent production of lymphocytes was found. There were no differences in lymphocytopoiesis between jejPP and ileal PP. The present data show major differences in the development, structure and function of PP in pigs in comparison to other species. These species-specific aspects are important for future studies on the immunological function of PP.
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Peyer's patches export lymphocytes throughout the lymphoid system in sheep.
The lymphocyte output from small intestine containing either the long continuous ileal Peyer's patch (PP) or several smaller jejunal PP was examined in young lambs. Most studies were done in 2-mo-old lambs, 1 mo after removal of mesenteric lymph nodes (MLN). Extracorporeal perfusion of part of the intestine and addition of fluorescein isothiocyanate to the perfusate led to the labeling, in their normal microenvironment, of a regionally defined population of cells. One day later considerable numbers of emigrant lymphocytes were identified by fluorescence microscopy in the spleen, MLN and peripheral lymph nodes, jejunal PP, and bone marrow. In nonperfused ileal PP and thymus the labeling indexes were low. The highest labeling index was in the blood where 3.7% of the lymphocytes were labeled. A similar organ distribution of emigrant cells was found on day 3. When MLN were included in the perfused region more emigrants were identified. In some animals the intestinal lymphatic draining the perfused ileum was cannulated. Continual lymph drainage caused a dramatic decrease in the labeling indexes in other lymphoid organs. A substantial number of lymphocytes leave both ileal PP and jejunal PP via lymphatics and travel to all other lymphoid organs. However, the number of emigrant lymphocytes compared with the total number of labeled lymphocytes in the perfused tissue was about 10 times greater after perfusing gut with the jejunal PP than after ileal PP perfusion. We conclude that relatively more lymphocytes emigrate from the jejunal PP than from the ileal PP.
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Coreconstitution of bacterial ATP synthase with monomeric bacteriorhodopsin into liposomes. A comparison between the efficiency of monomeric bacteriorhodopsin and purple membrane patches in coreconstitution experiments.
The conditions for coreconstitution of a bacterial ATP synthase and bacteriorhodopsin into lecithin liposomes and for light driven ATP synthesis have been optimized. A rate of maximally 280 nmol ATP min-1 mg ATP synthase-1 was achieved with monomerized bacteriorhodopsin compared with a rate of up to 45 nmol ATP min-1 mg-1 found for proteoliposomes containing bacteriorhodopsin in the form of purple membrane patches. The different rates are explained by the finding that monomeric bacteriorhodopsin is more homogeneously distributed among the liposomes than the purple membrane patches. The final activities depended on both the purification method for the two proteins and the coreconstitution procedure. Furthermore, the ratio (lipid to bacteriorhodopsin to ATP synthase) could be optimized. Light-driven ATP synthesis depends also on the type of detergent used. The best result was obtained by deoxycholate. Also the relationship between proton translocation (by bacteriorhodopsin) and ATP synthesis activity was measured. A constant H+/ATP ratio was found at higher light intensities. This ratio increased strongly at lower light intensities.
Bacteriorhodopsins↗
Exposure to formaldehyde in anatomy: an occupational health hazard?
The adverse effects of formaldehyde have been discussed very emotionally in public. Anatomists, technicians in histology and embalming laboratories, as well as medical students during their dissection course are all exposed to formaldehyde, which in many situations crosses the threshold for irritation of the eyes and upper respiratory tract. There is no doubt about the acute toxic effects and the occurrence of contact dermatitis caused by formaldehyde. Studies in rats and mice using high concentrations over an extremely long period (which would not be tolerated by humans) resulted in squamous carcinoma of the nose. Epidemiologic studies on the mortality of medical personnel exposed to formaldehyde do not provide sufficient evidence of cancerogenicity. A number of recommendations will be given for defining the exact concentration in a dissecting room or laboratory and for ways of reducing formaldehyde concentrations and thus minimizing adverse health hazards. These data could initiate a discussion among anatomists, and with technicians and students, based on a sound scientific background rather than on emotion.
Anatomy↗
The anatomical basis for the immune function of the gut.
The barrier function of the gut wall can be divided into different histotopographically defined lines of defence. These consist not only of lymphoid cells but also of goblet cells, entero-endocrine cells, macrophages and mast cells. Subsets of lymphoid cells are found preferentially within the epithelium (T suppressor) or in the lamina propria (T helper). Most plasma cells produce IgA. Peyer's patches are described in detail as typical organized lymphoid structures of the gut. In man, they are present well before birth and are found in large numbers even in old age. They are not only typical for the ileum but are also present in the duodenum and jejunum. The four compartments in Peyer's patches, i.e. follicle, corona, interfollicular area and the dome, are defined by the typical localization of lymphocyte subsets and by their different functions. Typical features of the epithelium of the dome are the lack of villi and goblet cells and the presence of specialized epithelial cells (M cells) which are important for the uptake of particulate antigen from the gut lumen. Precursor cells of IgA producing plasma cells leave the intestinal wall via the lymphatics and return preferentially to the gut mucosa, and this is summarized by the term gut-associated lymphoid tissue (GALT). Other organs with mucous membranes, such as mammary and salivary glands, bronchial and genital tract, are also included in this circulatory route and this is expressed by the term mucosa-associated lymphoid tissue (MALT). Mast cells in the gut mucosa can be classified as connective tissue or mucosa mast cells. These differ in their sensitivity to formaldehyde as a fixative, contain different granules and mediators, have different origins, and show major differences in the effectiveness of antiallergic compounds on the stabilizing of the cell membrane. Mucosa mast cells have also been demonstrated in the human gut. The histotopographical relationship of many cell types such as goblet and M cells in addition to cells of the immune system such as lymphoid cells, macrophages and mast cells, is essential in the understanding of the barrier function of the gut wall.
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Evidence of a selective major vascular marginal pool of lymphocytes in the lung.
The size and mobilization of the pulmonary vascular pool of lymphocytes was studied in young pigs. Blood lymphocytes, labeled in vitro with a fluorescent dye, were injected either intravenously or into the left heart. Comparable high numbers of lymphocytes were found in the lung after 30 min, demonstrating a specific homing of lymphocytes to the lung vascular bed. When the left lung was perfused with a cell-free medium for as long as 4 h in vitro, a continuous venous release of lymphocytes was found that resulted in about 1.5 x 10(9) lymphocytes and 5.7 x 10(6)/min leukocytes. Peripheral blood lymphocytes were labeled with 51Cr in vitro and injected intravenously. Fifteen minutes or 1 day later the lungs were perfused, and the release of cell-bound radioactivity was measured. The data indicate the existence of a large intravascular pulmonary lymphocyte pool. The sequestration of lymphocytes in the lung in many lymphocyte migration studies is not a removal of effete cells but a physiologic phenomenon.
Animals↗
[The intestines as an immune organ].
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Animals↗
[Anatomic principles for digestion and immune function in the gastrointestinal tract].
All the cells necessary for the afferent and efferent branch of the immune reaction are present in the intestinal wall. There is a continuous migratory flow of lymphatic cells (MALT = mucosa-associated lymphatic tissue). Experiments in oral immunisation have also recently provided data for clinical use of these migratory paths of IgA precursor cells. The mast cells in the mucosa show heterogeneity and can be differentiated not only by size, life span and origin, but also by the number of granules and the content of mediators. For further research on the cells in the immune system in the wall of the digestive tract new cell markers and functional tests are necessary.
Digestion↗