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Biomedical subjects

R Pabst

Publications and source records attributed to R Pabst.

At least 181 records · Page 10Linked to original sources
PubMed1990

Lymphocyte subsets in the blood. The influence of splenectomy, splenic autotransplantation, ageing, and the site of blood sampling on the number of B, T, CD4+, and CD8+ lymphocytes in the rat.

Removal of the largest single lymphoid organ, the spleen, leads to an increase in severe infections. To prevent this, transplantation of splenic fragments can be performed, which may, however, cause an increase in CD8+ lymphocytes in the blood of these patients. This is controversial since in the clinical situation it is often difficult to account for the different age of the patients, the time point after the operation and many other factors known to influence the number of lymphocyte subsets. Using a well-defined animal model, B, T, CD4+, and CD8+ lymphocytes were determined preoperatively in adult rats. Then, either sham splenectomy, splenectomy, or splenic autotransplantation was performed and the animals were followed up for 15 months after the operation. The surgical procedure itself, the site of blood sampling and ageing all influenced the number of lymphocyte subsets profoundly. Furthermore, giving the data as relative or absolute numbers leads to different results. Splenectomy caused lymphocytosis, due to a significant increase in B and CD8+ lymphocytes, as did splenic autotransplantation, which indicates that the number of lymphocyte subsets in the blood should not be used to argue in favour of or against splenic autotransplantation. This study demonstrates that the number of lymphocyte subsets in the blood is influenced by many factors and therefore should be determined in a highly standardized fashion.

Aging↗
PubMed1990

Is the bronchus-associated lymphoid tissue (BALT) an integral structure of the lung in normal mammals, including humans?

In the respiratory tract, lymphoid aggregates with a specialized epithelium have been called bronchus-associated lymphoid tissue (BALT) and compared to the organized lymphoid tissue of the gut (GALT), e.g., Peyer's patches. BALT might play a central role in antigen uptake, initiating immune responses and disseminating primed lymphoid cells in the respiratory tract. In the present study, lungs of mice, rats, guinea pigs, rabbits, pigs, cats, and humans have been studied with respect to the presence and number of BALT and the dependence of BALT on age and microbial stimulation. BALT is not a constitutive structure in all these species. Its frequency varies widely, from 100% in rabbits and rats, 50% in guinea pigs, 33% in pigs, to its absence in cats and all normal human lungs. BALT seems to be a lymphoid structure which is not present in all the species studied but can develop in the lung after stimulation. This is in contrast to lymphoid organs, such as lymph nodes or Peyer's patches, which can always be found. These species differences are of major importance in interpreting the clinical relevance of experiments in animal models on the lung immune system, e.g., antigen uptake, immunostimulation, or lung transplantation.

Aging↗
PubMed1990

Autotransplantation of lymph node fragments. Structure and function of regenerated tissue.

In pigs slices of autologous lymph nodes were implanted in the subcutaneous fat, under the muscular fascia or under the kidney capsule to study the regeneration of autotransplanted lymph node tissue. The regenerated nodules consisted of all the normal compartments found in lymph nodes and there was evidence that afferent lymphatics reached these nodules. Superficial inguinal lymph nodes regenerated more often and with a better structure than mesenteric lymph nodes. The sites under the kidney capsule and the fascia of muscles were found to be a less stimulating microenvironment for regeneration than the subcutaneous tissue. Regeneration of transplanted lymph node tissue was observed in pigs which had been operated on as young piglets or as adults. The regeneration of autotransplanted lymph node tissue might be a useful model for draining lymphedema, especially from the extremities.

Aging↗
PubMed1990

[Bronchoalveolar lavage in the pig--comparison of normal, pathogen-free and pneumonic animals].

The cells found in the BAL fluid of the pig were characterised morphologically and immunocytologically with monoclonal antibodies. The percentage of macrophages was found to be 80%, and that of lymphocytes, 20%. Granulocytes are characteristic when pneumonia is presenting. B-cells are rarely observed in germ-free animals, account for 5-8% in the normal animal, and are elevated in pneumonia. The percentage of T-helper cells is not changed by germ-free breeding or in the presence of pneumonia. In germ-free animals, the percentage of T-suppressor cells is reduced, but remains unchanged in pneumonia.

Animals↗
PubMed1990

Characterization of lymphatic and venous emigrants from the thymus.

Lymphocytes leaving the thymus via two different pathways were examined as to their morphology and phenotype. Cells leaving the thymus via lymphatics were obtained by a direct cannulation of thymic lymphatics and those leaving via the thymic vein were labelled within the thymus using an extracorporeal perfusion system and identified subsequently as fluorescent cells in the draining vein. In both cases the cervical thymus in lambs was used, since it is located in the neck region and ensures easy access to both blood and lymphatic vessels of the thymus without subjecting the animal to a major trauma or stress. Cells obtained from the thymic lymphatics or lymphatic emigrants were found to have distinct features different from peripheral T cells in terms of their surface morphology and expression of the MHC antigens. Venous emigrants were also slightly different from peripheral T cells in MHC expression. Estimation on the rate of thymocyte emigration into the periphery suggested that neither venous nor lymphatic emigrants represent a major fraction of de novo synthesized cells in the thymus of this animal species, as has been suggested in the mouse.

Animals↗
PubMed1990

Lymphocyte subsets and their proliferation in a model for a delayed-type hypersensitivity reaction in the skin.

A delayed-type hypersensitivity (DTH) reaction was induced in the skin of young pigs, by local injection of phytohaemagglutinin, and evaluation was carried out on the resulting accumulation of lymphocyte subsets and lymphocyte production by incorporation of bromodeoxyuridine in the skin and the draining lymph node. There was a rapid increase in mononuclear cells, which were found in clusters around venules. These included very few B lymphocytes, and CD8+ lymphocytes far outnumbered CD4+ cells. Underlining the importance of determining absolute numbers, the relative and absolute numbers of lymphocyte subsets showed quite different patterns during the development of the skin reaction. Lymphocytes in the normal skin incorporated the DNA precursor bromodeoxyuridine at higher rates than have been found for peripheral lymphoid organs. After intradermal phytohaemagglutinin injections, all subsets showed high proliferation rates in the skin, with kinetics which differed from the reaction in the draining lymph node. The labelling indexes of cells labelled with bromodeoxyuridine in vitro and in vivo were comparable. The phytohaemagglutinin injections also caused a marked and rapid increase in the proliferation of the cells in the basal layer of the epidermis. This model DTH-like reaction in skin with major CD8+ T-cell accumulation and proliferation locally and in the lymph nodes provides a reliable model for study of such reactions and for investigation of the regulatory role of cytokines.

Animals↗
PubMed1989

Immunohistological localization and characterization of FITC-labelled lymphocytes. A rapid and inexpensive method for studying migration.

Immunohistochemical methods are described for the detection and characterization of fluorescein isothiocyanate (FITC)-labelled lymphocytes on cryostat sections using an anti-FITC antibody. As a model, the localization of thoracic duct lymphocytes (TDL) in the rat spleen was examined at three time intervals. The kinetic patterns observed clearly differed between the four splenic compartments examined, namely: the red pulp, the marginal zone, the periarteriolar lymphatic sheath (PALS) and the follicle. Furthermore, the subset composition of the immigrant lymphocytes was determined by two colour immunohistochemical staining, which permitted simultaneous detection of the FITC label and surface markers. The results suggest that this method is a fast, easy and inexpensive approach to studies of lymphocyte migration.

Animals↗
PubMed1989

The mucosa of the male genital tract; part of the common mucosal secretory immune system?

The selective migration of mucosal-derived lymphoid blasts to other mucosal organs is taken to be an essential part of the common secretory immune system. In rats, proliferating lymphoid cells from mesenteric lymph nodes (mLN) and peripheral lymph nodes (pLN) were labeled in vitro using two different techniques, in order to test the hypothesis that the mucosa of the male genital tract is a preferential site for mLN lymphoid blasts to home to. A low but significant migration to male genital organs was found, but with no difference between blasts from pLN and mLN. Thus there is no evidence to include the male genital tract in the common mucosal secretory immune system. Recirculating lymphocytes from the thoracic duct entered the male genital organs with a similar distribution to the pattern of lymphoid blasts. There is probably an exchange between these immigrating lymphocytes and the different subsets, which are localized in the epithelium (T suppressor) and interstitial tissue (T helper) in male genital organs. The lymphoid cells in the male genital tract might play an important role in the immune function of seminal fluid and in sexually transmissible diseases.

Animals↗
PubMed1989

Proliferation of lymphocyte subsets in the adult rat: a comparison of different lymphoid organs.

Adult, male Lewis rats received a single injection of 5-bromo-2'-deoxyuridine (BrdUrd) i.v. to label proliferating cells in the S phase of the cell cycle. After 1 and 24 h the thymus, bone marrow, blood, spleen, peripheral, cervical and mesenteric lymph nodes as well as Peyer's patches were removed. In cell suspensions surface staining was performed for B, T, T helper (Th) and cytotoxic/suppressor (Tc/s) T lymphocytes by identifying kappa light chain, CD5+, CD4+ and CD8+ cells, respectively. On the same slide the DNA label BrdUrd was demonstrated by a monoclonal antibody. B, T, Th and Tc/s lymphocytes proliferate locally both in central lymphoid organs such as the thymus and the bone marrow, and in peripheral lymphoid organs such as the spleen, lymph nodes and Peyer's patches. Within an organ the amount of proliferation among the lymphocyte subsets is similar, differing not more than threefold. Although concerning only a small fraction of cells within the organ, an unexpected finding is the high percentage of BrdUrd-labeled cells among B lymphocytes in the thymus (3%) and among T lymphocytes in the bone marrow (3%). One day after injection of BrdUrd the thymus contains 25% BrdUrd+ T lymphocytes, while the other organs investigated do not show more than about 2% BrdUrd+ B and T lymphocytes. Many of the newly formed lymphocyte subsets leave their organ of birth within 24 h. Thus the amount of proliferation in the lymphocyte subsets investigated is very similar and the differences between central (thymus and bone marrow) and peripheral lymphoid organs are much smaller than expected.

Animals↗
PubMed1989

Proliferation of macrophage subpopulations in the adult rat: comparison of various lymphoid organs.

Adult male Lewis rats received a single intravenous injection of 5-bromo-2'-deoxyuridine (BRDU) to label all proliferating cells in the S-phase of the cell cycle. Various lymphoid organs were removed 1 and 24 hr after injection to assess local proliferation and migration of newly formed cells, respectively. In cell suspensions, surface staining was performed for macrophage subsets (ED1, ED2, ED3), and the DNA label BRDU was detected by a monoclonal antibody. Local proliferation of ED1+ macrophages occurred in all organs investigated with the exception of the blood. Bone marrow outweighed the other organs by far; in addition to the proliferating ED1+ promonocytes, the bone marrow also contained BRDU-labeled ED2+ macrophages. Newly formed ED1+ monocytes migrated into lymphoid organs such as the mesenteric lymph nodes and spleen where they comprised about 90% of newly formed macrophages. In the spleen, ED3+ macrophages seemed to be renewed by local proliferation, whereas in the mesenteric lymph nodes these cells were replaced by immigration. The heterogeneity of macrophages was further demonstrated by the different renewal of splenic macrophages. ED1+ and ED3+ cells were replaced in a matter of days, whereas it would probably take several months to renew ED2+ cells.

Animals↗
PubMed1989

Are all lymphoid blasts in the cell cycle? DNA synthesis in the lymphoid tissues of the dog.

Labelling index after one or repeated intravenous injections of 3H-thymidine was measured for various subpopulations of lymphatic cells in different canine lymphoid compartments and correlated with cell morphology. High doses of tritiated thymidine were injected and exposure times of up to 211 days were used. The labelling indices of lymphoid blasts were comparable in all tissues investigated. Labelling index varied from 100% in immunoblasts to 4% in small-sized lymphocytes. Approximately 80% of immunoblasts were labelled 1 h after 3H-thymidine application and 100% labelling was obtained after 12 h repetitive 3H-thymidine labelling. In contrast with medium-sized and large lymphocytes, immunoblasts seem to be rapidly proliferating cells in the dog with almost no Go cells.

Animals↗
PubMed1989

Migration pattern of lymphocyte subsets in the normal rat and the influence of splenic tissue.

Lymphocyte subsets leave the blood and appear in the thoracic duct of normal rats at different rates. The aim of the present study was to investigate their migration pattern through blood, spleen, bone marrow, mesenteric lymph nodes, and Peyer's patches in normal Lewis rats and to study the role of the spleen using splenectomized and spleen-transplanted animals. Fluorescein isothiocyanate (FITC)-labelled thoracic duct lymphocytes (TDL) were injected intravenously into rats and after 15 min, 1, 6, and 24 h the percentages of B, T, T helper (TH) and T-cytotoxic/suppressor (TC/S) lymphocytes in the FITC+ cells were determined in cell suspensions by means of monoclonal antibodies. B and T lymphocytes are preferentially localized in different organs, e.g. B cells in Peyer's patches and T cells in mesenteric lymph nodes. The migration of TH lymphocytes differed from that of TC/S lymphocytes in all the organs investigated. In the late phase after injection the migration of B and TH lymphocytes was influenced by the spleen, since after splenectomy the number of injected B lymphocytes increased and that of TH lymphocytes decreased in all organs investigated except the bone marrow. Splenic autotransplantation could not normalize the disturbed migration.

Animals↗
PubMed1989

Numbers and heterogeneity of mast cells in the male genital tract of the rat.

Normal adult rats were used to quantitate and characterize mast cells in the male genital tract. The tissues were either fixed in a fixative containing formalin (Schaffer solution) or with basic lead acetate (BLA) to identify 'connective-tissue mast cells' and 'mucosal mast cells', respectively. In the epididymis and seminal vesicle small numbers of mast cells were identified without any obvious heterogeneity. In the prostate, however, a mean of 45.1 +/- 9.3 and 23.0 +/- 4.0 mast cells/mm2 was found after BLA and Schaffer fixation, respectively. This difference might be of functional and clinical significance.

Animals↗
PubMed1989

Mast cell heterogeneity in the small intestine of normal, gnotobiotic and parasitized pigs.

A formalin fixative and a formalin-free fixative were used to study mast cells in the small intestine of conventional, gnotobiotic and parasitized pigs. Many more mast cells were identified after basic lead acetate fixation ('mucosal mast cells', MMC) than after routine formalin fixation ('connective tissue mast cells'). The MMC were preferentially localized in the lamina propria. There were no differences between conventional and gnotobiotic pigs. However, in parasitized animals, the number of mast cells was several times higher, mainly because there were more MMC. The heterogeneity of intestinal mast cells in the pig indicates that this might be an interesting model for functional studies on mast cell subsets.

Aging↗
PubMed1989

What is the function of peripheral lymphocytes migrating to the thymus and of B lymphocytes proliferating in the thymus?

In studies on the role of other lymphoid organs in lymphocyte production and lymphocyte migration in young pigs and lambs, lymphocytes from these tissues were always found in the thymus. There were no major differences in the entry of labelled cells when the spleen, lymph nodes, bone marrow or Peyer's patches were selectively labelled. The immigrants were both mature small lymphocytes and lymphocytes just produced in the peripheral lymphoid organs. They enter via specialized venules at the outer part of the thymic medulla and do not migrate into the cortex. The lymphocyte homing is markedly reduced by prior incubation with trypsin. The relative numbers of immigrants within the thymus were small but, due to the huge cellular content of the thymus, the absolute number entering per day totalled several million from each peripheral organ. Another unexpected finding was the high mitotic rate in the medulla of the thymus. Moreover, in the adult rat thymus although there were only 0.14% B cells, these proliferated at a higher rate than in peripheral organs. The functional meaning of these data is obscure so far and the studies should stimulate further work on these topics of lymphocyte entry and B lymphocyte production in the thymus.

Animals↗
PubMed1989

Lymphocyte subsets in jejunal and ileal Peyer's patches of normal and gnotobiotic minipigs.

The size and location of Peyer's patches (PP) in the jejunum and ileum and their composition of lymphocyte subsets (B, CD2+, CD4+, CD8+) have been studied in conventional and gnotobiotic Göttingen minipigs. Each PP in the small intestine remained at the same site and was of comparable length between 2 and 12 months of age. In 1.5-month-old conventional minipigs the histology of the compartments differed between the continuous PP in the terminal ileum (ilPP) and the discrete PP in the jejunum (jejPP). No such difference was seen in gnotobiotic or in 12-month-old animals. The composition of lymphocyte subsets showed striking differences with significantly more B and less T, CD4+ and CD8+ cells in ilPP in 1.5-month-old minipigs in comparison with 12-month-olds. Mesenteric lymph nodes and jejPP displayed a typical pattern of lymphocyte subsets. The size of the lymphocyte compartments in PP and their cellular composition depends largely on age and microbial influences from the gut lumen, which might be of major importance for studies on the function of the gut-associated immune system in the pig.

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