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G Groenewegen

Publications and source records attributed to G Groenewegen.

35 records · Page 2Linked to original sources
PubMed1986

Cyclosporin A inhibits IL 2-driven proliferation of human alloactivated T cells.

The influence of cyclosporin A (CsA) on the interleukin 2 (IL 2)-driven proliferation of allo-activated human T lymphocytes has been studied. CsA (50, 100, and 250 ng/ml) appeared to affect the IL 2-driven proliferation. The impaired proliferation could not be reversed with exogenous interferon-gamma. The doubling time of the cell populations appeared to increase with higher CsA doses. The cytotoxic capacity of the cells was also strongly inhibited by CsA. The cells regained proliferative and cytotoxic properties after CsA has been removed and cells were additionally cultured in normal medium. The data strongly suggest that CsA has an inhibitory influence on essential basic processes in T cells.

Cyclosporins↗
PubMed1986

Alloantigen presentation by canine endothelial cells. Presentation of autologous alloantigens in vitro.

Presentation of autologous alloantigen by certain cells in an allograft can result in allograft rejection. The precise type of cell in a graft responsible for this aspect of allograft rejection remains to be established. Here we report the capacity of canine venous endothelial cells to activate, in vitro, allogeneic lymphocytes for proliferation and differentiation by presentation of alloantigen. Antigen-presenting cell (APC)-depleted lymphocyte populations, prepared in a multistep procedure and tested for absence of APC, were cocultured with allogeneic venous endothelial cells. Proliferation and differentiation into cytotoxic T lymphocytes were measured. While mixed lymphocyte culture of APC-depleted lymphocytes did not result in proliferation and differentiation, coculture of allogeneic APC-depleted lymphocytes with venous endothelial cells resulted in proliferation and generation of cell-mediated cytotoxicity in these cultures. It is concluded that canine venous endothelial cells in vitro have the capacity to present alloantigen. The data suggest an essential role for endothelium in the initial phase of allograft rejection.

Animals↗
PubMed1986

Canine MHC-class II antigens on B and T lymphocytes.

MHC-class II antigens on canine lymphoid cells were detected with monoclonal antibodies (Mabs). On the basis of reactivity with resting or activated T lymphocytes two groups of Mabs were reported earlier. Non-activated T lymphocytes expressed MHC-class II antigens recognized by the first group whereas the second group recognized only MHC-class II antigens on activated T lymphocytes. In this study we analysed the reactivity pattern of both groups of Mabs with purified canine B lymphocytes. One- and two-colour immunoflowcytometric analysis, immunoprecipitation, immunohistology and MLC inhibition were performed. The Mabs which only reacted with activated T lymphocytes appeared to stain also purified sIg+ lymph node cells. Two-colour fluorescence and immunohistology confirmed the reactivity of these Mabs with B lymphocytes. Immunoprecipitation showed the bimolecular structure of these antigens. It was concluded that two subsets of MHC-class II antigens can be detected on canine lymphoid cells. One subset showed an aberrant distribution being expressed on both nonactivated and activated T and on B lymphocytes. The second subset of MHC-class II antigens could only be detected on B lymphocytes and activated T lymphocytes, a distribution pattern similar to that found in most other species, for instance man.

Animals↗
PubMed1985

Lymphokines induce changes in morphology and enhance motility of endothelial cells.

The influence of lymphokines, the soluble mediators produced by lymphocytes, on the morphology and the motility of endothelial cells in vitro is described. Lymphokines induced an altered morphology and an increased motility of canine and human venous endothelial cells. The action of the lymphokines was species specific. The data are discussed in relation to in vitro and in vivo data on the behavior of endothelial cells in inflammation. The in vitro experiments allow further study of the role of endothelial cells in inflammatory and immunological processes.

Animals↗
PubMed1985

Cell-mediated cytotoxicity patterns of cloned cytotoxic T lymphocytes. Cytotoxicity directed against canine lymphoblasts, monocytes, and endothelial cells.

Knowledge of the antigens recognized during allograft rejection is still incomplete. Cloned cytotoxic T lymphocytes were used to study the distribution of target determinants in the dog. CTL clones were obtained with a limiting dilution technique from effector cells generated in mixed lymphocyte culture. The clones have been tested for cell-mediated cytotoxicity against PHA-stimulated lymphoblasts, monocytes, and arterial and venous endothelial cells. A limited number of patterns of lysis of one, or more than one, of the four different target cells was observed. The nature of the possible target determinants recognized by these CTL-clones is discussed.

Animals↗
PubMed1985

Effect of cyclosporine on MHC class II antigen expression on arterial and venous endothelium in vitro.

MHC class II antigens play a crucial role in immunological responses. The expression of MHC class II antigens on monocytes and endothelial cells is reported to be variable and able to be induced by gamma-interferon. In this study we report on MHC class II antigen expression in vitro by arterial and venous canine endothelial cells, as detected with FACS analysis and indirect immunofluorescence with a monoclonal antibody against canine MHC class II antigens. It appears that cultured endothelial cells do not express MHC class II antigens. Their expression could be induced during a three-day incubation period in lymphokine-containing supernatant produced in mixed leukocyte culture (MLC). Cyclosporine (CsA) added to allogeneically stimulated or unstimulated canine lymphocytes in MLC inhibited the induction of expression by the MLC supernatant. The addition of CsA to MLC supernatant did not have an inhibitory effect. It is concluded that CsA inhibits the production of an MHC class-II-antigen-inducing lymphokine produced by lymphocytes in mixed cultures; allogeneic stimulation is not necessary for production of the lymphokine. It is postulated that a possible mode of action of CsA in prolongation of allograft survival is based on prevention of the induction of MHC class II antigen expression by endothelial cells.

Animals↗
PubMed1985

Class II antigens on canine T lymphocytes.

A panel of crossreactive anti-human, -mouse and -rat MHC class II monoclonal antibodies (Mabs) was used to examine MHC class II antigen expression on canine T lymphocytes by cytofluorometry. The presence of MHC class II antigens was demonstrated on activated T lymphoblasts as well as on non-stimulated peripheral blood T lymphocytes. A number of anti-MHC class II Mabs reacted only with activated T lymphoblasts. Immunoprecipitation studies confirmed the Ia-like or MHC class II molecular character of the antigens on canine T cells. The expression of MHC class II antigens on peripheral blood T lymphocytes appeared to be not induced by stimulation of the T cells, as purified T lymphocytes of specific pathogen free dogs reacted with anti-MHC class II Mabs. Moreover, the study indicates that MHC class II antigen expression is present in the neonatal thymus. Lectin stimulated and allogeneically stimulated T lymphoblasts showed a stronger expression of MHC class II antigens in comparison with non-stimulated T cells.

Animals↗
PubMed1984

Canine IL-2: characterization and optimal conditions for production.

The culture requirements for the production of canine I1-2 are reported. Several parameters have been tested, such as concentration of lectin, length of culture period and presence of the additives serum, polyethylene glycol (PEG) and phorbol myristic acetate (PMA). Optimal results have been obtained by stimulation of peripheral blood leukocytes with the lectin PHA (8 micrograms/ml) for 48 h. Techniques for the production of I1-2 containing supernatant free of PHA have been evaluated. Gel filtration chromatography of culture supernatant revealed that canine I1-2 has a molecular weight (m.w.) of approximately 30,000 daltons, similar to the m.w. of I1-2 produced by murine T cells.

Animals↗
PubMed1984

In vitro stimulation of lymphocytes by vascular endothelial cells. A study with canine arterial and venous endothelial cells.

Data are presented on the ability of arterial and venous endothelial cells to stimulate allogeneic leukocytes. Mixed cultures of allogeneic endothelium and lymphocytes result in proliferation of lymphocytes and generation of cell-mediated cytotoxicity, which do not occur in cultures of syngeneic combinations of endothelium and lymphocytes. Studies of kinetics showed a peak in proliferation at days 6-7. The optimal responder-stimulator ratio appeared to be 15:1. Lymphocytes stimulated with venous endothelial cells were cytotoxic both for arterial and for venous endothelial cells and PHA blasts of the stimulator dog, whereas lymphocytes stimulated with arterial endothelial cells lysed only arterial endothelial cells and PHA blasts of the stimulator. Lysis of syngeneic or third-party allogeneic control targets was virtually absent. Optimal conditions for long-term culture of effector cells from mixed leukocyte endothelial cell cultures were analyzed. Addition of Il 2 every 3 days and the original stimulating antigen every 6 days permitted continuous proliferation of these cytotoxic lymphocytes with preservation of the cytotoxicity pattern.

Animals↗
PubMed1984

Influence of a skin allograft on frequencies of CTL precursor in peripheral blood of the dog.

Alloantigen-specific cytotoxic T lymphocytes (CTL) and their precursors (CTL-P) have been determined in the peripheral blood of skin allografted dogs. CTL-P frequencies increased rapidly after transplantation and reached maximal values after complete rejection of the skin allograft. Differences in the time response kinetics of CTL-P frequencies between recipients were not correlated with the length of graft survival. The CTL-P frequencies declined after days 13-20 and appeared still to be elevated 30 days after rejection of the graft.

Animals↗
PubMed1984

Vascular endothelial cells present alloantigens to unprimed lymphocytes.

Antigen-presenting cells (APC) were removed from canine peripheral blood by carbonyl iron treatment and adherence to plastic and to nylon-wool. This treatment resulted in low proliferation in mixed lymphocyte cultures (MLC) and lack of generation of cell-mediated cytotoxicity (CMC) in depleted cell suspensions compared with untreated cell suspension. The proliferative response could be restored to normal by the addition of low numbers of autologous arterial or venous endothelial cells to the MLC of depleted cell suspensions. Cytotoxicity against phytohaemagglutinin-stimulated lymphoblasts of the stimulator was generated in the untreated MLC and also in the MLC of APC-depleted cell suspensions with endothelial cells added. It is concluded that arterial and venous endothelial cells can substitute for APC in the proliferative response of autologous lymphocytes against alloantigen and in the generation of CMC. Therefore, endothelial cells have an alloantigen-presenting capacity.

Animals↗
PubMed1984

Cell-mediated cytotoxicity toward class I and class II antigens on canine T and B lymphoblasts.

Cellular cytotoxicity generated in vitro has been studied with canine T and B lymphoblasts as target cells. B lymphocytes were isolated by rosetting with protein A labeled sheep red blood cells and stimulated with sepharose bound protein A. Such highly purified stimulated B lymphoblasts appeared to be useful target cells for cellular cytotoxicity. Cold target inhibition studies and limiting dilution analysis revealed that B lymphocytes did not carry targets for cytotoxic T lymphocytes (CTL) which were not present on PHA stimulated T lymphoblasts.

Animals↗
PubMed1983

Limiting dilution analysis of canine alloantigen-reactive T lymphocytes.

A sensitive limiting dilution assay for the determination of canine cytotoxic T lymphocyte precursors (CTL-P) has been developed. Murine second MLC supernatant as a source of Interleukin 2 (IL 2) was used to expand stimulated CTL-P to numbers that were easily detectable with the classic 51Cr lysis assay. The frequencies of CTL-P that reacted to allogeneic stimulator cells in canine peripheral blood ranged from 1:1000 to 1:2000 lymphocytes. During in vitro stimulation in a mixed leukocyte culture a rapid increase in frequency was noted, and at day 7 a frequency as high as 1:5.4 was found. The presence of irradiated stimulator cells during limiting dilution culture restricted proliferation of the CTL-P; only those which recognized the stimulator cells proliferated. The determination of cytotoxicity in large numbers of individual microcultures with CTL-P seeded at clonal conditions toward 2 allogeneic target cells permitted quantitation of the frequency of CTL-P with specificity for different alloantigens. These techniques greatly facilitate monitoring of cellular immune reactions after renal allografting because both determination of the influence of cytostatic drug treatment on CTL-P frequency, and analysis of the specificity and function of allograft infiltrating cells are now possible.

Animals↗
PubMed1983

Cellular cytotoxicity against canine endothelial cells. Analysis of determinants recognized by CTL.

A method is described which permits culture of both arterial and venous canine endothelial cells. Cell-mediated cytotoxicity against cultured endothelial cells has been studied. A 51Cr-release assay was used to detect CTL generated in MLC. Both arterial and venous endothelial cells are lysed by CTL specifically. Cold target inhibition experiments have been performed to analyse the CTL-recognized antigens on arterial and venous endothelial cells. Different antigens are recognized by CTL on venous endothelial cells and PHA-blasts; it is possible that CTL recognize venous endothelial cells through class II antigens or E-M antigens. Arterial endothelial cells and PHA-blasts share CTL-recognized antigens.

Animals↗
PubMed1982

Analysis of buoyant density of canine peripheral blood leukocytes with PVP-Silica (Percoll) density gradients.

Isolation of canine peripheral blood mononuclear cells with a one step centrifugal separation procedure has not been very successful sofar. Significant contamination with polymorphonuclear cells has been reported. An analysis of the buoyant density of canine peripheral blood leukocytes on a self-generating Percoll gradient showed that the buoyant densities of polymorphonuclear cells and lymphocytes are so near that separation with high purity and yield is not possible with the use of a density gradient. Transient changes in buoyant density of polymorphonuclear cells have been observed. In such situations differences in buoyant density between cell types have been observed which permit separation of mononuclear cells from polymorphonuclear cells at a reasonable yield.

Animals↗
PubMedDate not supplied

Lymphokine dependence of in vivo expression of MHC class II antigens by endothelium.

Changes in the expression of class II antigens of the major histocompatibility complex (MHC) have an integral role in the regulation of immune responses, and are brought about in vitro by soluble mediators. However, the mechanism that underlies in vivo expression of MHC class II antigens in, for example, endothelial cells in the absence of immunological stimulation has not been studied. We demonstrate here that expression of MHC class II antigens is not a constitutive property of endothelial cells, for MHC class II antigen-positive endothelial cells do not express these antigens during treatment with the immunosuppressive agent cyclosporin A. In vivo MHC class II antigen expression by canine endothelial cells is therefore dependent on factors, probably the lymphokine gamma-interferon produced by the immune system, whose secretion is inhibited by cyclosporin A.

Animals↗