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Biomedical subjects

G Kraal

Publications and source records attributed to G Kraal.

At least 163 records · Page 9Linked to original sources
PubMed1985

In vivo effects of LPS on B lymphocyte subpopulations. Migration of marginal zone-lymphocytes and IgD-blast formation in the mouse spleen.

The aim of the present study was to analyze the effect of LPS on the localization and differentiation of splenic B lymphocytes. Therefore, we used a double immunoperoxidase technique which enabled us to detect both the IgM+ IgD- marginal zone lymphocytes and the IgM+ IgD+ follicular lymphocytes in the same tissue section. Next to a dramatic disappearance of the predominantly IgM+ IgD- lymphocytes in the marginal zone shortly after an intravenous injection of LPS, an increased number of these cells could be found in the splenic follicles. The present results strongly suggest that the IgM+ IgD- cells in the splenic follicles represent immigrating marginal zone lymphocytes, and not differentiating follicular B cells, because no IgM+ IgD- cells could be observed in the follicles of draining lymph nodes shortly after a subcutaneous injection of a similar amount of LPS. These observations support the suggestion that LPS induces a migration of marginal zone lymphocytes into the follicles. The present results also showed the formation of IgD plasmablasts in the inner PALS and around the terminal arterioles of the spleen after LPS administration. The induction of IgD plasmablasts appeared to be a specific effect of LPS which may be related to its toxic properties.

Animals↗
PubMed1985

Effects of a single oral dose of dinitrochlorobenzene on T lymphocyte distribution and migration in the gut.

In the present study the effects of a large oral dose of the contact allergen dinitrochlorobenzene (DNCB) on the distribution of T-cell subsets in the small intestines and the emigration pattern of lymphocytes from Peyer's patches were investigated. Apart from the inflammatory effects, DNCB administration resulted in an influx on the T-helper cells in the villi. Precise quantification of T lymphocytes showed a decrease in Peyer's patches and an increase in mesenteric lymph node cell suspensions. However, no differences could be found in the emigration rate of T-cell subsets from Peyer's patches into mesenteric lymph nodes, suggesting that the increase of T cells in mesenteric lymph nodes results from T-helper cells directly immigrating from the villi.

Allergens↗
PubMed1985

Intra-intestinal priming leads to antigen-specific IgA memory cells in peripheral lymphoid organs.

The aim of this study was to gain more insight into the mechanism of IgA memory formation by testing the effects of intra-intestinal antigen priming on various booster routes. To obtain a primary immune response trinitrophenyl conjugated keyhole limpet haemocyanin (KLH-TNP) was injected into the lumen of the small intestines of mice. For secondary immune responses mice were boosted intra-intestinally, intravenously or subcutaneously. The distribution of antigen specific cells in situ was demonstrated by enzyme histochemistry whereas quantification of TNP-specific cells was performed with a plaque-forming cell assay. After single or repeated intra-intestinal antigen administrations both primary and secondary immune responses in terms of specific antibody containing cells were mainly located in the spleen. The anti-TNP antibody-containing cells produced predominantly IgM during the primary and IgM, IgG and IgA during the secondary response. In mesenteric lymph nodes and villi antigen-specific cells were detected sporadically. When intra-intestinal priming was followed by intravenous or subcutaneous booster injections most anti-TNP antibody-producing cells were demonstrated in the spleen and in the draining popliteal lymph nodes. In contrast to repeated intravenous or subcutaneous immunizations alone, these organs contained, besides specific IgM and IgG cells, many TNP-specific cells producing IgA antibodies. This result demonstrates that the production of IgA antibodies is not restricted to mucosa-associated lymphoid tissues. IgA memory cells are induced in mucosa associated lymphoid tissues, probably in Peyer's patches, will consecutively migrate throughout the whole lymphoid system and can be triggered by renewed antigen contact to become IgA plasma cells.

Animals↗
PubMed1985

The specificity of the high endothelial venule in bronchus-associated lymphoid tissue (BALT).

By using an in vitro binding assay, the specificity of T and B cell adherence on high endothelial venules (HEV) of bronchus-associated lymphoid tissue (BALT) was studied in the rat and the guinea pig. It was found that the adherence specificity of the BALT HEV is different from that found in Peyer's patches and more closely resembles the specificity of the HEV in mesenteric lymph nodes. The data are discussed in view of a common mucosal immune system.

Animals↗
PubMed1985

The heterogeneity of mononuclear phagocytes in lymphoid organs: distinct macrophage subpopulations in the rat recognized by monoclonal antibodies ED1, ED2 and ED3.

In the present study, a set of three monoclonal antibodies is described, each of which recognizes cells of the monocyte-macrophage lineage in the rat. The tissue distribution, in particular in lymphoid organs, of each of the three monoclonals is determined by immunoenzyme histochemistry on cryostat sections, as well as on cell suspensions. Results show that ED1 recognizes a cytoplasmic antigen in monocytes and in most macrophages, free and fixed. ED2 and ED3 recognize membrane antigens of tissue macrophages, discriminating between distinct subpopulations of macrophages, each with a characteristic localization in the compartments of lymphoid organs. No other cell types except cells of the mononuclear phagocyte system are positive for any of the three monoclonals. Possible relations between the macrophages recognized by this set of monoclonals and dendritic cells are discussed.

Animals↗
PubMed1985

Marginal zone macrophages identified by a monoclonal antibody: characterization of immuno- and enzyme-histochemical properties and functional capacities.

In the present study, the non-lymphoid cell of the marginal zone is described: the marginal zone macrophage, identified by a monoclonal antibody, ERTR9. The characteristics of these cells were investigated by use of a two-step immunoperoxidase method (on light and ultrastructural level) in combination with enzyme-cytochemical techniques and functional tests. The marginal zone macrophage appears to be a large cell with close contacts between its cell processes and surrounding marginal zone B cells, and with a well-developed phagocytic capacity. These ERTR9-positive macrophages are capable of selective uptake and retention of i.v. injected FITC-Ficoll and are negative for Ia antigen as well as for the macrophage-related F4/80 antigen. By these characteristics, they constitute a subpopulation of non-lymphoid cells of spleen unique for the marginal zone.

Animals↗
PubMed1984

Selective emigration of suppressor T cells from Peyer's patches.

The emigration of Peyer's patch lymphocytes to mesenteric lymph nodes was studied by injecting fluorescein isothiocyanate (FITC) directly into Peyer's patches. Using double immunofluorescence it was demonstrated that at 2 and 4 hr after FITC injection 70% of the labeled cells that migrated to mesenteric lymph nodes were T lymphocytes, although rat Peyer's patches contain only 15-20% T lymphocytes. At later time points after FITC injection this percentage of T cells derived from Peyer's patches gradually declined, most likely caused by selective interaction and/or retention inside the mesenteric lymph node. Determination of helper and suppressor T-cell subsets within this emigrating population showed an increased number of T suppressor cells migrating into mesenteric lymph nodes. The putative role of suppressor T cells in inducing systemic tolerance after oral antigen administration was discussed.

Animals↗
PubMed1984

The interaction of high endothelial venules with T and B cells in peripheral lymph nodes after antigenic stimulation.

The influence of an ongoing immune response on the specific interaction of high endothelial venules (HEV) in peripheral lymph nodes with T and B cells was determined using short-term homing experiments and an in vitro HEV adherence assay. It was demonstrated that stimulation with various antigens did not change the receptor specificity of the HEV. However, the retention and/or the efflux of immigrant cells in the stimulated lymph nodes had changed.

Animals↗
PubMed1983

Genetic control of T-cell subset representation in inbred mice.

Lyt-2+ T cells constitute a significantly greater proportion of the total peripheral T-cell population in C57BL mice than in BALB/c and other mouse strains. The inheritance of this differential representation of Lyt-2- vs. Lyt-2+ T cells was studied by two-color immunofluorescence analysis of peripheral T cell subsets in BALB/c, C57BL, F1 and F2 generations, and in CXB recombinant inbred strains. It was shown that the C57BL phenotype (low Lyt-2-/Lyt-2+ ratio) is a dominant Mendelian character. Studies of subpopulations of thymocytes and of early thymus emigrants indicate that the representation of mature Lyt-2- and Lyt-2+ T cells is influenced by mechanisms of selection or differential turnover in the peripheral lymphoid organs, but that thymic and prethymic influences may also play a role.

Animals↗
PubMed1983

Differences in in vivo distribution and homing of T cell subsets to mucosal vs nonmucosal lymphoid organs.

The migratory properties of Lyt-2- and Lyt-2+ T cells in the mouse have been investigated. In short-term in vivo homing studies, Lyt-2- T cells localized consistently more efficiently than Lyt-2+ T cells in Peyer's patches (about 1.5 times as well), whereas both populations localized roughly equivalently in peripheral lymph nodes. These homing characteristics of Lyt-2- and Lyt-2+ subsets are largely independent of their organ source. The specificity of migration appears to be determined by selective recognition of organ-specific determinants on the endothelial cells of high endothelial venules (HEV), specialized venules that mediate the exit of migrating lymphocytes from the blood: In an in vitro assay of lymphocyte binding to HEV in lymphoid organ frozen sections, Lyt-2- cells constituted a significantly and consistently greater proportion of T cells binding to Peyer's patch HEV than of those binding to peripheral node HEV. The homing and HEV recognition preferences of the Lyt subsets are reflected in differences in their in situ representation in mucosal vs nonmucosal lymphoid organs, which suggests that the selective migration of these populations may be an important factor in determining the character of local immune responses.

Animals↗
PubMed1982

Germinal centre B cells: antigen specificity and changes in heavy chain class expression.

Germinal centres are histologically defined aggregates of blast cells that occur in B-cell areas of lymphoid tissues after antigenic stimulation. They are believed to be associated with the development of B-cell memory and plasma cell (especially secondary, IgG and IgA) responses. Recent studies of murine lymphoid tissues have defined cell-surface markers that distinguish germinal centre B cells from other mature B cells, permitting their identification and characterization in cell suspensions. Here we have used these markers to define and study germinal centre cells in lympho nodes, and have found that they constitute a unique population of B cells which (1) arises in response to antigenic stimulation, (2) contains nearly all of the demonstrably antigen-specific B cells in the stimulated organ, (3) bears surface IgM after primary stimulation and (4) as a population, demonstrates isotype switching to a predominant population, demonstrates isotype switching to a predominant surface IgG phenotype after secondary stimulation with specific surface IgG phenotype after secondary stimulation with specific antigen. These findings demonstrate that germinal centres are a major site of proliferation and differentiation of antigen-specific B cells in vivo, and suggest that the germinal centre microenvironment may have an important role in heavy chain class switching during B-cell responses.

Animals↗
PubMed1981

The influence of the thymus on precursor T cells.

The influence of the thymus on its bone marrow precursors was investigated: T cell differentiation was studied in irradiated mice reconstituted with bone marrow from thymectomized donors. Up to twelve months after TX the influx of precursors and differentiation into T cells were not changed in the recipients. CFU-s determination of bone marrow and spleen from thymectomized animals did not show a change in numbers but during ageing a shift of the E/G ratio was observed in thymectomized as well as control donors.

Animals↗