PubMed Health⌕ Search

Biomedical subjects

J Rozing

Publications and source records attributed to J Rozing.

At least 73 records · Page 4Linked to original sources
PubMed1989

A monoclonal antibody against rat platelets. I. Tissue distribution in vitro and in vivo.

In this study we describe a new monoclonal antibody (MoAb PL.1) against rat platelets. Immunohistology of various rat tissues showed staining of platelets, especially in the spleen, and staining of megakaryocytes in bone marrow and spleen red pulp. In the liver small platelet aggregates and endothelial cells were stained. After in-vivo administration of MoAb PL.1 an acute severe thrombocytopenia was observed. In general the distribution of the antibody and/or antibody-coated platelet aggregates showed the same pattern as after in-vitro incubation, i.e. staining of rat platelets and platelet aggregates in spleen red pulp, and staining of megakaryocytes in spleen and bone marrow. Platelet aggregates were observed in the liver and electron microscopy indicated that they were associated with Kupffer cells. Furthermore, liver endothelial cells were positively stained. Comparison of the molecular weight of the antigens recognized by this MoAb and by human anti-platelet MoAbs, as well as comparison of staining patterns of megakaryocytes indicated that MoAb PL.1 is probably directed to a GPIIb/IIIa complex analogue. Since MoAb PL.1 is of the non-complement-binding mouse IgG1 isotype, it can be used for studying clearance of platelet aggregates by Fc-receptors of the MPS. It also promises to be a useful tool in the study of platelet involvement in rats with experimental nephritis.

Animals↗
PubMed1989

Immunoregulation in Heymann nephritis. I. Cell marker studies.

Immunoregulation was examined in rats with Heymann nephritis (HN), an established model of membranous glomerulonephropathy (MGN). There is little known of the cellular immune events for the induction and maintenance of the autoimmune response in HN. The cell marker studies utilized fluorescein (FITC)-labelled monoclonal antibodies directed to B cells (Mark-I), and T cell subsets: pan T (ER-I), helper/inducer T (ER-2) and suppressor/cytotoxic T (ER-3). Lymphoid subsets were compared in spleen, lymph nodes, peripheral blood and bone marrow, of normal and diseased rats. Animals were investigated during the induction and chronic phases of disease. The induction of HN was associated with an early, significant, but transient increase of the non-specific myeloid component of the defence system. Subsequently, a significant increase was seen in the number of cells of the B lymphocyte lineage in HN animals, which coincided well with the overall increased humoral immune responsiveness. No alterations in the T lymphocyte subsets were noted during the development of this experimental autoimmune disease.

Animals↗
PubMed1989

Immunoregulation in Heymann nephritis. II. Functional studies.

In this study, the functional properties of the cells involved in the immunoregulation of Heymann nephritis (HN) have been investigated. HN is a disease model in the rat where the pathology closely resembles membranous glomerulonephropathy (MGN) in man. This autoimmune model is induced by injection of renal tubular antigen (RTA) incorporated in Freund's complete adjuvant (FCA). The strong B cell and plasma cell response in the chronic phase of HN, as determined by cell marker analyses, is predominantly antigen-non-specific. The secondary response pattern found was not only to RTA upon repeated immunization, but also to non-related antigen (SRBC). Although cell marker studies have indicated no major quantitative changes in the T cell population throughout the development of HN, a severe deregulation of the cellular immune response is observed especially during the induction period of HN. This was shown by a strong decrease of the mitogen-induced proliferative response and IL-2 production. This phenomenon is caused by both defective cellular components and inhibitory serological factors. Finally, in the chronic phase, these aberrations gradually return to normal.

Animals↗
PubMed1988

Mercuric chloride-induced autoimmunity in the brown Norway rat. Cellular kinetics and major histocompatibility complex antigen expression.

HgCl2 induces an autoimmune syndrome in Brown Norway rats that involves synthesis of anti-glomerular basement membrane (GBM) antibodies and development of nephritis with high proteinuria. HgCl2-induced changes in the composition of leukocyte populations and in the expression of MHC antigens in lymphoid and nonlymphoid organs were investigated by flow cytometry and immunohistochemistry. An early increase of CD4+ splenocytes was followed by a transient proliferation of CD4+ as well as CD8+ and B lymphocytes in peripheral lymphoid organs; in contrast, progressive depletion of the thymic cortex was found. B lymphocyte activation involved mainly the IgG1 and IgE isotypes. Nonlymphoid organs were infiltrated by MHC class II antigen expressing CD4+ and CD8+ T lymphocytes and monocytes; secondary to infiltration, mainly epithelial cells, being the main target of infiltrating cells, showed increased expression of MHC antigens. In glomeruli a 2.7-fold increase of CD8+ lymphocytes occurred after HgCl2-administration. The diverse autoimmune phenomena observed in this study fit with the hypothesized involvement of T lymphocytes autoreactive with MHC class II antigens. Apart from anti-GBM autoantibodies, a role for autoreactive CD8+ T lymphocytes must be considered in the pathogenesis of the HgCl2-induced autoimmune syndrome.

Animals↗
PubMed1987

Implantation of cultured thymic fragments in congenitally athymic (nude) rats. Influx of lymphocytes and dendritic cells.

We studied the early events in athymic immunoincompetent rats after implantation with cultured thymic fragments (CTF) under the kidney capsule, with special emphasis on the settlement of lymphocytes and non-lymphoid RT1 class II elements. At 2 weeks after grafting, tissue under the kidney capsule comprises strands of keratin-positive epithelial cells from the graft, without immigrant cells. At 3 weeks, the CTF graft is populated with lymphocytes and with non-lymphoid RT1 class II-positive cells expressing the recipient haplotype (allogeneic combinations). Part of these cells bear determinants recognized by an anti-rat dendritic cell antibody. At 4 weeks the graft exhibits a completely restored thymic architecture. At the periphery, the first indications of T-cell competence generated after CTF implantation are observed 6 weeks after implantation. At 18 weeks, the peripheral thymus-dependent immune system is almost completely developed. This includes in vitro alloreactivity, even to the donor RT1 haplotype of the graft. But skin grafts of the allogeneic CTF donor haplotype are not rejected. Thus, a state of in vivo tolerance is induced under the influence of grafted epithelium, which is not due to a specific deletion of alloreactive cells. We conclude that CTF regain their original thymic architecture between 2 and 4 weeks after implantation in (allogeneic) athymic nude recipients, and that only after this restoration does peripheral thymus-dependent immune competence start to develop.

Animals↗
PubMed1986

Implantation of cultured thymic fragments in congenitally athymic nude rats: ignorance of thymic epithelial haplotype in generation of alloreactivity.

We studied the development of thymus-dependent immunity in congenitally athymic nude rats after implantation of cultured thymic fragments (CTF), particularly the development of in vitro alloreactivity in allogeneic combinations. CTF of DA (RT1a), PVG (RT1c), and RP (RT1p(u,1] origin were implanted in nude rats of WAG (RT1u) origin. In analysis 14 to 18 wk later, all recipients exhibited thymus-dependent immunocompetence assessed by (immuno)-histology of lymphoid organs and responsiveness to in vitro concanavalin A stimulation and in vivo ovalbumin immunization. Control nude animals were unresponsive. Also, in vitro alloreactivity was observed, measured by mixed lymphocyte reaction and cell-mediated lympholysis. The alloresponse to the allogeneic CTF donor haplotype was as to a third party, but that to the recipient was negative. The CTF before implantation were devoid of lymphoid elements and revealed epithelial-like cells as the major component. Cells in CTF showed expression of RT1 class I and class II antigens. CTF at autopsy had the architecture of a normal thymus. In immunohistochemistry using haplotype-specific antibodies, lymphocytes showed RT1u class I expression as in the normal WAG thymus. In the cortex-like area of CTF, stromal cells revealed class I and class II haplotype expression of the donor thymus, but in the medulla-like area, class II haplotype expression was that of the recipient WAG rat. These data indicate that after implantation in nude rats, CTF become populated not only with lymphoid elements, but also with stromal components from the recipient. In induction of thymus-dependent immunity, these acceptor-derived stromal (dendritic) cells may be involved in generation of allospecificity; class I and class II haplotype expression by the donor cortex (epithelial) compartment is ignored in this process.

Animals↗
PubMed1986

B lymphocyte-associated antigens on terminal deoxynucleotidyl transferase-positive cells and pre-B cells in bone marrow of the rat.

To investigate early stages of B lymphocytopoiesis in rat bone marrow (BM) before the expression of surface IgM (s mu), the populations of cytoplasmic mu-chain-positive (c mu+) pre-B cells and terminal deoxynucleotidyl transferase-positive (TdT+) cells were studied by double immunofluorescence microscopy. B lymphocytes that were s mu+ constituted 5%, c mu+s mu- pre-B cells 23%, and TdT+ cells 4% of nucleated cells in the BM of juvenile rats. TdT+ and pre-B cells ranged between 7 and 17 microns in diameter. TdT+ cells were slightly larger, with a modal diameter of 10.5 microns against 9 microns for pre-B cells. mu-Chains were absent from nearly all TdT+ cells. Their surface antigenic phenotype was studied by using a panel of mouse monoclonal antibodies (MAb) to rat B lymphocyte-associated antigens (Ig, Ia, and others) and T lymphocyte-associated antigens. Both pre-B cells and TdT+ lacked surface Ig and Ia but carried most of the other B lymphocyte-associated antigens analyzed. TdT+ and pre-B cells lacked those antigens found only on the T lineage. By using MAb HIS24 (detecting a non-Ig/Ia B lymphocyte-associated antigen) and fluorescence-activated cell sorting, TdT+ and pre-B cells were highly enriched. The results show that most TdT+ cells in rat BM are mu- but demonstrate strong similarity with pre-B cells in surface antigenic phenotype. Therefore, as suggested for man, a major proportion of rat BM TdT+ cells may be B lineage-cells before mu heavy chain gene expression.

Animals↗
PubMed1986

Inhibition of iodothyronine transport into rat liver cells by a monoclonal antibody.

The role of the rat liver plasma membrane in the regulation of uptake and subsequent deiodination of thyroxine (T4) or the biologically active thyroid hormone 3,3',5-triiodothyronine (T3) was investigated. Here we report on the production of monoclonal antibodies raised against rat hepatocytes. Two antibodies were selected. Antibody ER-22 did bind to a Mr 52,000 membrane protein and inhibited the 1- and 5-min uptake of both T4 and T3 by primary cultured rat hepatocytes in a dose-dependent fashion. As the uptake of T4 and T3 depends on the presence of a sodium gradient over the plasma membrane, the inhibitory potency of ER-22 on the Na+,K+-ATPase activity was investigated. No inhibition of the uptake of 86Rb+ could be determined, indicating that antibody ER-22 is not directed against the Na+,K+-ATPase but probably the carrier protein itself. Clearance of T3 from the medium and concomitant iodide production by cultured rat hepatocytes during a 20-h incubation in the presence of ER-22 were both inhibited by 50% with respect to a control incubation in the absence of monoclonal antibody, pointing to the importance of carrier-mediated transport in cellular uptake and metabolism of T3. A second monoclonal antibody did bind to two other plasma membrane proteins but did not inhibit transport of thyroid hormone.

Animals↗
PubMed1986

Acute glomerulonephritis after intravenous injection of monoclonal anti-thymocyte antibodies in the rat.

Female Wistar rats were injected with (mouse) monoclonal antibodies (Moabs) of different IgG subclasses directed to rat thymocytes or rat tumor cells. Following intravenous injection of antithymocyte Moabs, glomerular binding of mouse IgG was observed during the first 4 days along the GBM and in the mesangium. No staining for mouse IgG was detected in anti-tumor Moab injected rats. Animals injected with IgG 2a anti-thymocyte Moab developed glomerulonephritis and a massive proteinuria in contrast to rats injected with IgG 1 Moab which is non-complement fixing. The glomerulonephritis lesion consisted of microaneurysms and focal and segmental proliferation. Deposits of complement and fibrin could be detected exclusively in rats injected with IgG 2a anti-thymocyte Moab during the whole observation period of 14 days. This is the first demonstration of overt glomerulonephritis lesions on the injection of monoclonal antibodies.

Animals↗
PubMed1986

The specificity of nephritogenic antibodies. IV. Binding of monoclonal antithymocyte antibodies to rat kidney.

Polyclonal rabbit antirat thymocyte serum (ATS) has been shown to form in situ glomerular immune aggregates following perfusion into normal rat kidney ex vivo. This may be due to the presence of T-cell-like epitopes in the rat kidney, or it may be a result of contaminating anti-connective-tissue antibodies in ATS. To exclude the latter possibility we investigated binding to the rat kidney of three different (mouse) monoclonal antirat thymocyte antibodies (anti-T-cell MoAbs), directed to Thy 1.1 antigen, as well as (control) anti-B-cell MoAbs. The MoAbs were incubated in vitro with kidney sections or perfused into the blood-free rat kidney ex vivo. It was shown using immunofluorescence (IF) and immunoelectron microscopy (IEM) (peroxidase technique) that the anti-T-cell MoAbs used, in contrast to anti-B-cell MoAbs, are able to bind with glomerular capillary walls, and with mesangial structures after incubation in vitro or perfusion ex vivo. Although staining patterns are not completely identical, the reaction product is clearly demonstrated throughout the glomerular basement membrane (GBM) and along the plasma membranes of endothelial and epithelial cells, after contact with either of the three anti-T-cell MoAbs used. It is concluded that the presence of T-cell-like epitopes in the rat kidney may lead to immune complex formation following contact with anti-T-cell MoAbs. The nephritogenicity of rabbit ATS, as well as of some batches of clinically used ATS, may also be explained by this mechanism rather than by the usually assumed presence of contaminating antibodies in these polyclonal antisera.

Animals↗
PubMed1986

T-cell development during ageing in congenitally athymic (nude) rats.

We studied the thymus-dependent immune system in congenitally athymic (nude) rats of the WAG (RT-1u) strain, at the ages of 2, 3, 5, 9, and 17 months. This included the histology of spleen, lymph nodes, and Peyer's patches, immunohistochemistry on tissue sections, and immunocytology on cell suspensions using a panel of monoclonal antibodies to T-lymphocyte subpopulations, in vitro mitogen responsiveness, and in vivo responsiveness to ovalbumin immunization. The results were compared with those in euthymic immunocompetent littermates of the same age. The cell marker analysis, especially in nude animals, was hampered by the staining of non-T cells by some of the antibodies (staining of putative macrophages, natural killer cells, cells of B-lymphocyte lineage, and of myeloid lineage). Despite this, with age an increase in cells with these markers was observed; for instance, in spleen suspensions, cells labelled by the pan-T reagent MRC OX-19 increased from 5% at 2 months to 19% at 17 months (value in euthymic animals 34%). In the other assays too a gradual increase of T-cell reactivity with age was observed, from almost absent in 2- and 3-month-old nude rats to values in 17-month-old animals of about half the level found in euthymic rats. However, none of the nude animals responded to ovalbumin immunization. These results indicate that in nude animals processes occur which compensate for the absent intrathymic T-cell generation. This applies in particular to changes in T-cell phenotype and mitogen responsiveness, but not to antigen responsiveness.

Aging↗
PubMed1986

Glomerulonephritis induced by monoclonal anti-Thy 1.1 antibodies. A sequential histological and ultrastructural study in the rat.

The present report describes the natural history of an experimental acute glomerulonephritis with massive proteinuria induced by a single intravenous injection of a (mouse) monoclonal anti-rat Thy 1.1 antibody into the rat. The disease is characterized by direct although transient binding of this monoclonal antibody to glomerular basement membrane and mesangium after injection as demonstrated by immunofluorescence microscopy. Immediate activation of complement occurs as shown by glomerular deposition of C3 and C9. Concomitant activation of the coagulation cascade is reflected by the presence of fibrinogen deposits in the affected glomeruli. One hour after injection mesangial alterations are prominent including condensation of mesangial cell chromatin, and lysis of mesangial cells as shown by light- and electron- microscopy, leading to the formation of aneurysms in the capillary tuft. Commencing on day 4 mesangial cell proliferation can be observed, accompanied by glomerular crescent formation at day 14, which decreases gradually 3 weeks after antibody administration, whereas mesangial hypercellularity can be observed up week 10 after intravenous injection of the antibody. The disease is clinically characterized by a massive transient proteinuria starting immediately after antibody injection, reaching mean values of 300 mg/24 hours at days 2 to 4, gradually decreasing to normal levels after 3 weeks. It is concluded that in this unique model of glomerulonephritis induced by a monoclonal antibody, recognition of Thy 1.1 epitopes as well as activation of complement including the C5-C9 membrane attack complex may play a major role in the pathogenesis of this experimental disease.

Animals↗