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K J Wood

Publications and source records attributed to K J Wood.

At least 19 recordsLinked to original sources

Altered proximal T-cell receptor signalling events in mouse CD4+ T cells in the presence of anti-CD4 monoclonal antibodies: evidence for reduced phosphorylation of Zap-70 and LAT.

Anti-CD4 monoclonal antibodies are potential therapeutic agents for the prevention of autoimmune disease and treatment of rejection after organ transplantation and are capable of both restoring tolerance to self-antigens and inducing tolerance to antigens introduced under the cover of the antibody therapy in vivo. Tolerance to donor alloantigens can be induced in vivo by administering donor alloantigen in combination with either depleting (YTA 3.1) or nondepleting (YTS 177) anti-CD4, 28 days before heart transplantation in the mouse. The effect of anti-CD4 on proximal T-cell receptor (TCR) signalling pathways and proliferation was investigated in vitro and in vivo in the presence and absence of YTA 3.1 or YTS 177. Anti-CD4 was found to perturb proximal signalling events upon TCR/CD3 ligation, resulting in reduced tyrosine phosphorylation of Zap-70 and LAT (linker for activation of T cells) and reduced association of tyrosine-phosphorylated LAT with lck. This ultimately resulted in severely reduced proliferation of the responding CD4+ T cells. The signalling profile of the anti-CD4-treated cells resembled that of anergic T cells. This could be a result of a common mechanism involving perturbation in the formation of the central supramolecular activation cluster of the immunological synapse by impaired recruitment of CD4 and CD28, thereby resulting in severely reduced lck activation.

Adaptor Proteins, Signal Transducing↗

Adenoviral transfer of a single donor-specific MHC class I gene to recipient bone marrow cells can induce specific immunological unresponsiveness in vivo.

We investigated the delivery of a donor-specific MHC class I gene, H-2K(b), using a newly constructed replication-defective recombinant adenovirus (AdSV40K(b)) to recipient tissue before transplantation as a means of inducing donor-specific immunological unresponsiveness. AdSV40K(b) was able to transduce both a fibroblast cell line and freshly isolated bone marrow cells (BMCs) resulting in cell surface expression of H2-K(b) protein. Intravenous infusion of AdSV40K(b)-transduced syngeneic CBA/Ca (H-2(k)) BMCs into CBA recipient mice treated with an anti-CD4 monoclonal antibody 27 days before transplantation of a fully MHC-mismatched, C57BL/10 (H-2K(b+)), cardiac allograft resulted in significant long-term graft survival when compared with mice receiving the same dose of syngeneic BMCs transduced with a control adenovirus, AdRSVbetagal. Despite the induction of H-2K(b)-specific hyporesponsiveness following pretreatment with AdSV40K(b)-transduced CBA BMCs, persistence of H-2K(b) mRNA in central or peripheral tissues could not be demonstrated by RT-PCR. This result was in contrast to the observed persistence of K(b) mRNA both in the periphery and thymus following the infusion of transgenic CBK (H-2(k) + K(b)) BMCs. We conclude that ex vivo adenoviral gene transfer of a single donor MHC class I gene to recipient BMCs in combination with transient depletion of CD4(+) cells is sufficient to induce long-term graft survival of a fully allogeneic cardiac graft. In addition, detectable microchimerism is not a prerequisite for graft survival.

Adenoviridae↗

Suppression mediated by anergic CD4+ T cells requires stimulation by MHC-peptide complexes and can be induced in the presence of costimulation.

BACKGROUND: In this study, we have investigated the mechanisms involved in both the induction of suppressive anergy, the stability of the anergy induced, and the possible mechanisms by which the response of immunocompetent CD4+ T cells are suppressed. METHODS: We used immobilized anti-CD3 monoclonal antibody (mAb) to induce anergy in T helper (Th) 1 and Th0 cells reactive with MHC class II molecule H2 I-Ab. RESULTS: We observed that suppressive anergy was induced independently of costimulation in Th0 but not Th1 cells. Although the anergic and suppressive states of Th0 cells were stable in the presence of exogenous interleukin-2, this was not the case for Th1 cells. No evidence for linked epitope suppression was observed for any of the I-Ab reactive cells investigated. Neither anergy nor suppression was observed in Th0 cells upon restimulation with anti-CD3 in the presence of syngeneic antigen-presenting cells (APCs). However, anergy but not suppression was observed in co-cultures restimulated with anti-T-cell antigen receptor (TCR) mAbs/syngeneic APCs and suppression could be restored by the addition of I-Ab+ APCs. CONCLUSIONS: Overall, these data suggested that the MHC-peptide complex recognized by the Th0 cells was required for suppression of the response of immunocompetent cells. We propose that suppression is mediated either by down-modulation of the MHC-peptide complex recognized by the anergic T cells or that a molecule specific to the MHC-peptide/TCR interaction facilitates negative regulation by APC:T or T:T interactions.

Animals↗

Critical role for IL-4 in the development of transplant arteriosclerosis in the absence of CD40-CD154 costimulation.

Blockade of the CD40-CD154 pathway can inhibit CD4(+) T cell activation but is unable to prevent immune responses mediated by CD8(+) T cells. However, even in the absence of CD8(+) T cells, inhibition of the CD40-CD154 pathway is insufficient to prevent the development of transplant arteriosclerosis. This study investigated the mechanisms of transplant arteriosclerosis in the absence of the CD40 pathway. C57BL/6 CD40(-/-) (H2(b)) recipients were transplanted with MHC-mismatched BALB/c (H2(d)) aortas. Transplant arteriosclerosis was evident in both CD40(-/-) and CD40(+/-) mice (intimal proliferation was 59 +/- 5% for CD40(-/-) mice vs 58 +/- 4% for CD40(+/-) mice) in the presence or absence of CD8(+) T cells (intimal proliferation was 46 +/- 7% for CD40(-/-) anti-CD8-treated mice vs 50 +/- 10% for CD40(+/-) anti-CD8-treated mice), confirming that CD8(+) T cells are not essential effector cells for the development of this disease. In CD40(-/-) recipients depleted of CD8(+) T cells, the number of eosinophils infiltrating the graft was markedly increased (109 +/- 24 eosinophils/grid for CD40(-/-) anti-CD8-treated mice vs 28 +/- 7 for CD40(+/-) anti-CD8-treated mice). The increased presence of eosinophils correlated with augmented intragraft production of IL-4. To test the hypothesis that IL-4 was responsible for the intimal proliferation, CD8 T cell-depleted CD40(-/-) recipients were treated with anti-IL-4 mAb. This resulted in significantly reduced eosinophil infiltration into the graft (12 +/- 5 eosinophils/grid for CD40(-/-) anti-CD8(+), anti-IL-4-treated mice vs 109 +/- 24 for CD40(-/-) anti-CD8-treated mice), intragraft eotaxin, CCR3 mRNA production, and the level of intimal proliferation (18 +/- 5% for CD40(-/-) anti-CD8(+)-, anti-IL-4-treated mice vs 46 +/- 7% for CD40(-/-) anti-CD8-treated mice). In conclusion, elevated intragraft IL-4 production results in an eosinophil infiltrate and is an important mechanism for CD8(+) T cell-independent transplant arteriosclerosis in the absence of CD40-CD154 costimulation.

Animals↗

Alloantigen-induced specific immunological unresponsiveness.

When the immune system encounters alloantigen it can respond in any one of a number of different ways. The choice that is made will take into account factors such as where, when and how the contact with the alloantigen takes place, as well as the environmental conditions that prevail at the time the alloantigen is encountered. Alloantigen administration before transplantation either alone or in combination with therapeutic agents that modulate the functional activity of the responding leucocytes can be a powerful way of inducing specific unresponsiveness to alloantigens in vivo. The molecular mechanisms that influence the way the outcome of the immune response to alloantigen develops, either activation or unresponsiveness to the triggering antigen, hold the key to our ability to manipulate the immune system effectively by exposing it to donor antigen for therapeutic purposes. This review will focus on alloantigen-induced immunological unresponsiveness and how insights into the mechanisms of unresponsiveness have driven the development of novel tolerance-induction strategies that show promise for translation into the clinic in the future.

Animals↗

IL-10 is required for regulatory T cells to mediate tolerance to alloantigens in vivo.

We present evidence that donor-reactive CD4(+) T cells present in mice tolerant to donor alloantigens are phenotypically and functionally heterogeneous. CD4(+) T cells contained within the CD45RB(high) fraction remained capable of mediating graft rejection when transferred to donor alloantigen-grafted T cell-depleted mice. In contrast, the CD45RB(low) CD4(+) and CD25(+)CD4(+) populations failed to induce rejection, but rather, were able to inhibit rejection initiated by naive CD45RB(high) CD4(+) T cells. Analysis of the mechanism of immunoregulation transferred by CD45RB(low) CD4(+) T cells in vivo revealed that it was donor Ag specific and could be inhibited by neutralizing Abs reactive with IL-10, but not IL-4. CD45RB(low) CD4(+) T cells from tolerant mice were also immune suppressive in vitro, as coculture of these cells with naive CD45RB(high) CD4(+) T cells inhibited proliferation and Th1 cytokine production in response to donor alloantigens presented via the indirect pathway. These results demonstrate that alloantigen-specific regulatory T cells contained within the CD45RB(low) CD4(+) T cell population are responsible for the maintenance of tolerance to donor alloantigens in vivo and require IL-10 for functional activity.

Adoptive Transfer↗

Differential susceptibility of heart, skin, and islet allografts to T cell-mediated rejection.

Although it is widely accepted that there is a hierarchy in the susceptibility of different allografts to rejection, the mechanisms responsible are unknown. We show that the increased susceptibility of H-2K(b+) skin and islet allografts to rejection is not based on their ability to activate more H-2K(b)-specific T cells in vivo; heart allografts stimulate the activation and proliferation of many more H-2K(b)-specific T cells than either skin or islet allografts. Rejection of all three types of graft generate memory cells by 25 days posttransplant. These data provide evidence that neither tissue-specific Ags nor, surprisingly, the number of APCs carried in the graft dictate their susceptibility to T cell-mediated rejection and suggest that the graft microenvironment and size may play a more important role in determining the susceptibility of an allograft to rejection and resistance to tolerance induction.

Animals↗

Permissible and immunogenic HLA-A mismatches: cytotoxic T-cell precursor frequencies reflect graft survival data.

Analysis of the in vivo immunogenicity of single HLA mismatches, in the context of a patient's own human leukocyte antigen (HLA) phenotype, has been used to define permissible and immunogenic HLA mismatches. Kidney graft survival in the case of permissible mismatches was similar to that of completely HLA matched combinations, whereas immunogenic mismatches lead to a significantly poorer graft survival. The present study tested whether such permissible and immunogenic HLA mismatches are reflected in the in vitro cytotoxic T-lymphocyte (CTL) allorepertoire. Limiting dilution experiments were performed to analyze the number of precursor CTL directed against individual HLA class I antigens. In general, the frequency of CTLp directed against permissible HLA-A antigens (n = 70, mean frequency 27 CTLp per million peripheral blood lymphocytes [PBL]) was found to be significantly lower compared with the CTLp directed against immunogenic HLA-A antigens (n = 73, mean frequency 59 CTLp per million PBL). The difference was found both in healthy individuals and a population of renal transplant candidates. These results were confirmed by a retrospective analysis of CTLp frequencies performed between partly mismatched unrelated bone marrow donors and their potential recipients. In conclusion, on the population level the permissible and immunogenic HLA-A mismatches are indeed reflected in the CTL allorepertoire. However, due to the big overlap of the CTLp frequencies in these populations, the permissible or immunogenic nature of a mismatch for a particular patient should be determined on an individual basis.

Cells, Cultured↗

Gene therapy in transplantation.

In transplantation, gene therapy strategies to prolong graft survival involve gene transfer and expression of immunomodulatory or graft-protecting molecules. The local production of immunosuppressive molecules has the potential to reduce their systemic side effects, and to increase their bioavailability and hence their therapeutic efficiency. Ex vivo gene transfer enables manipulation prior to engraftment. Vectors have now been developed that can optimally transfer the relevant genes to various cells, tissues and organs. The elimination of genetically modified cells can even be time-controlled by prodrug administration in suicide gene therapy systems. Gene transfer to stem cells may eventually lead to accelerated tissue repair and regeneration. In addition, xenotransplantation and organ cloning techniques have the potential to resolve the current shortage of donor organs.

Animals↗

Islet allograft rejection can be mediated by CD4+, alloantigen experienced, direct pathway T cells of TH1 and TH2 cytokine phenotype.

BACKGROUND: It is widely believed that Thl cells that secrete interferon-gamma are primarily involved in the rejection of allografts whereas Th2 cells [interleukin(IL) 4 and IL-10] are thought to be protective of this process. However, the exact role and specificity of these helper T lymphocytes in mediating allograft damage is presently unknown. METHODS: Th0, Th1, and Th2 cell lines specific for the class II MHC molecule H2IAb were adoptively transferred into T cell deficient, syngeneic, diabetic mice before transplantation of fully allogeneic C57BL/10 (H2b) or (CBKxBALB/c)F1 (H2k/d+Kb) islet grafts. T cells were 5-(and-6-)-carboxyfluorescein diacetate succinimidyl ester- (CFSE) labeled to allow detection, immunohistochemistry was performed, and IL-4 transcripts within the rejected islet grafts were quantified by reverse transcriptase polymerase chain reaction (RT-PCR). RESULTS: Adoptive transfer (IV) of Th0-, Th1-, and Th2 IAb-specific T cells resulted in rejection of H2b islet allografts. CFSE-labeling demonstrated that these T cells were able to home to the graft site. CD4+ T cells and CD11b+ macrophages were present within the graft after adoptive transfer of both Thl and Th2 cells. Interestingly, CD8+ T cells and B cells were absent from these rejecting grafts. Even when Th2 cells were introduced directly at the graft site, prompt rejection was still observed despite the presence of increased IL-4 mRNA expression within the islet allografts. CONCLUSIONS: Th2 and Th0 alloreactive CD4+ T helper cells can reject islet grafts with similar efficiency to Th1 cells. These results suggest that deviation of the immune response from a Th1 to Th2 phenotype will not be sufficient to allow successful engraftment of allogeneic organs or tissues.

Animals↗

Nondepleting anti-CD4 monoclonal antibody enhances the ability of oral alloantigen delivery to induce indefinite survival of cardiac allografts: oral tolerance to alloantigen.

BACKGROUND: We examined whether oral administration of alloantigen could induce the prolonged survival of cardiac allografts. METHODS: Hearts from CBK (H2k+Kb) transgenic or (C57BL/10xCBA)F1 (H2bxH2k) mice were transplanted into CBA (H2k) recipients pretreated orally with 1 x 10(7) donor splenocytes in the presence or absence of a nondepleting anti-CD4 (YTS 177, 200 microg/dose). RESULTS: Modest prolongation of CBK cardiac grafts was induced in CBA mice fed with multiple doses of CBK splenocytes (MST 42 days compared with controls fed with syngeneic CBA splenocytes, 12 days). When the CD4 monoclonal antibody, YTS177, was administered for 2 days before the first oral delivery of CBK splenocytes, all mice accepted their grafts indefinitely (MST > 100 days versus mice treated with anti-CD4 alone, 11.5 days). To determine if feeding multiple doses of alloantigen was essential, CBA mice were given CBK splenocytes orally on a single occasion in combination with the anti-CD4. The majority of the grafts survived indefinitely (MST >100 days). This oral treatment regimen also induced indefinite prolongation of (C57BL/10xCBA)F1 cardiac grafts. CONCLUSION: The induction of unresponsiveness by oral administration of alloantigen can be augmented by a nondepleting anti-CD4, YTS177, when given before the first oral delivery of allogeneic cells.

Administration, Oral↗

Intragraft interleukin-4 mRNA expression after short-term CD154 blockade may trigger delayed development of transplant arteriosclerosis in the absence of CD8+ T cells.

BACKGROUND: It has recently been shown that, although anti-CD154 induces CD4+ T-cell tolerance, it is unable to prevent allograft rejection mediated by CD8+ T cells. We have also shown that anti-CD154 monotherapy does not protect the graft from the development of transplant arteriosclerosis even in the absence of CD8+ T cells. This study was designed to investigate and characterize possible mechanisms responsible for the development of transplant arteriosclerosis after CD154 blockade in the absence of CD8+ T cells. METHODS: C57BL/6 (H2b) recipients received a fully MHC-mismatched BALB/c donor aorta (H2d). Animals were either treated with anti-CD154 monoclonal antibody (mAb) in the presence or absence of CD8 T cells. Histology, morphometric measurements, immunohistochemistry, and the production of alloantibodies (IgM, IgG1, IgG2a) were analyzed on days 14, 30, and 50 after transplantation. Cytokine production within the graft was investigated by competitive reverse transcription-polymerase chain reaction on day 14. RESULTS: Combined treatment with anti-CD154 and a depleting CD8 mAb resulted in a delay in the development of transplant arteriosclerosis (intimal proliferation: 33+/-10% vs. 67+/-11% untreated control, day 30) but ultimately did not prevent its progression (intimal proliferation: 55+/-10% vs. 78+/-9% untreated control, day 50). Although there was a significant decrease in the number of CD4+, CD11b+, and CD40+ graft-infiltrating cells and a reduction in the formation of donor-specific IgG1 alloantibodies in recipients treated with anti-CD154 and anti-CD8 mAbs, mRNA for interleukin (IL)-4 was increased, suggesting a shift in the intragraft cytokine profile towards a Th2-like pattern. CONCLUSIONS: Our data provide evidence that short-term CD154 blockade is insufficient to prevent transplant arteriosclerosis, even in combination with CD8+ T-cell depletion. Moreover, the increased expression of the Th2 cytokine interleukin-4 within the graft may be responsible for the development of transplant arteriosclerosis in the long term.

Animals↗

CD40-CD40 ligand-independent activation of CD8+ T cells can trigger allograft rejection.

In experimental transplantation, blockade of CD40-CD40 ligand (CD40L) interactions has proved effective at permitting long-term graft survival and has recently been approved for clinical evaluation. We show that CD4+ T cell-mediated rejection is prevented by anti-CD40L mAb therapy but that CD8+ T cells remain fully functional. Furthermore, blocking CD40L interactions has no effect on CD8+ T cell activation, proliferation, differentiation, homing to the target allograft, or cytokine production. We conclude that CD40L is not an important costimulatory molecule for CD8+ T cell activation and that following transplantation donor APC can activate recipient CD8+ T cells directly without first being primed by CD4+ T cells.

Animals↗

CD8+ T cells contribute to the development of transplant arteriosclerosis despite CD154 blockade.

BACKGROUND: The CD40-CD154 receptor-ligand pair plays a critical role in allograft rejection by mediating the activation of endothelial cells, antigen-presenting cells, and T cells. Blockade of this interaction prevents acute allograft rejection and leads to prolonged allograft survival in numerous experimental models, but in most cases indefinite graft survival is not achieved due to evolving transplant arteriosclerosis. In this study, we have used a model of transplant arteriosclerosis to investigate whether CD4+ and CD8+ T cells are differentially affected by CD154 blockade. METHODS: BALB/c (H2d) aortic grafts were transplanted into C57BL/6 (H2b) recipients treated with anti-CD154 monoclonal antibody in the presence or absence of CD8+ T-cell depletion. Histology and morphometric measurements were performed on day 30 after transplantation. RESULTS: Only combined treatment with anti-CD154 and anti-CD8 monoclonal antibodies resulted in a significant reduction of intimal proliferation (33 +/-10% vs. 67+/-14%; untreated control). Administration of either antibody alone did not produce this effect. Thymectomy did not alter the degree of intimal proliferation observed in any of the treatment groups. CONCLUSIONS: Our data provide direct evidence that CD8+ T cells are not targeted effectively by CD154 blockade and that the transplant arteriosclerosis seen after CD154 blockade is not due to recent thymic emigrant T cells.

Animals↗

Fas ligand-transfected myoblasts and islet cell transplantation.

BACKGROUND: Expression of Fas ligand (FasL, CD95L) within the local environment of an allograft may protect from rejection by inducing apoptosis of infiltrating T cells. However, there is mounting evidence that ectopic expression of FasL stimulates an inflammatory response and targets the FasL-expressing tissue for destruction. Given the potential therapeutic applicability of FasL-based immune protection, we sought to determine whether ectopic FasL expression was detrimental and to analyze the inflammatory response induced by ectopic FasL expression in the absence of any confounding allo-immune responses. METHODS AND RESULTS: Two myoblast cell lines expressing different levels of functional FasL were produced. Co-implantation of FasL-expressing myoblasts with syngeneic islets allowed examination of the inflammatory response induced by ectopic FasL expression. In contrast to the suggested benefits of localized FasL expression, islets co-implanted with FasL-expressing myoblasts were destroyed in a vigorous inflammatory response predominated by neutrophils. Interestingly, FasL expression also had a marked anti-tumor effect. CONCLUSIONS: Unless FasL-dependent neutrophil-mediated inflammation can be prevented, it is unlikely that this strategy will be useful for preventing allograft rejection.

Animals↗

Visualization of the in vivo generation of donor antigen-specific effector CD8+ T cells during mouse cardiac allograft rejection: in vivo effector CD8+ T cell generation during allograft rejection.

BACKGROUND: An adoptive transfer system was used to study the fate of alloreactive CD8+ H-2Kb-specific TCR transgenic (DES+) T cells in vivo after transplantation. METHODS: A trace population of 2.0x10(6) CD8+DES+ T cells were adoptively transferred into syngeneic CBA.Ca (H-2k) mice 24 hr before transplantation of an H-2Kb+ or H-2Kb- cardiac allograft. RESULTS: H-2Kb specific T cells proliferated and produced interleukin-2 and interferon-gamma in response to H-2Kb+, but not H-2Kb- cardiac allografts. CD8+DES+ T cells that infiltrated the H-2Kb+ cardiac allografts developed a distinct cell surface and cytokine phenotype compared with the CD8+DES+ T cells that remained in the periphery. H-2Kb-specific graft infiltrating T cells (a) underwent a larger number of cell divisions (> =3), (b) increased in size, (c) up-regulated CD69, and (d) down-regulated CD62L. CONCLUSIONS: These results demonstrate that alloantigen-specific T cells can be monitored in vivo during the immune response to an allograft and that the fate of CD8+ T cells specific for the allogeneic class I molecules expressed by the graft is different between cells in the periphery and those that infiltrate the graft.

Adoptive Transfer↗

The importance of H2 haplotype sharing in the induction of specific unresponsiveness by pretransplant blood transfusions.

BACKGROUND: The beneficial effect on graft survival achieved by pretransplant blood transfusions is well established. Previous studies have shown that the degree of major histocompatibility complex (MHC) (mis)-match between the transfusion donor and the recipient plays a determining role. However, other factors are also involved. In this study, we explored the hypothesis that, in addition to sharing of MHC antigens between the transfusion donor and the recipient, the MHC type of the organ donor is also of importance. METHODS: To mimic the human situation, F1 mice, rather than inbred strains, were pretreated with haplotype-shared allogeneic whole blood transfusions and transplanted with hearts of organ donors with different matched or mismatched H2 haplotypes. RESULTS: When a heart was transplanted 1 week after donor-specific transfusion (DST; blood transfusion donor=organ donor), an excellent prolongation of graft survival was obtained (median survival time: 77 days vs. 9 days in untreated mice). However, this was only the case when a haplotype was shared with the recipient; a DST given with no match between organ donor (=BT donor) and recipient did not induce any prolongation. Furthermore, in order to obtain the optimal beneficial effect of a haplotype-shared blood transfusion, the other haplotype of the transfusion donor had to be mismatched with the recipient. The immunogenetic studies showed that haplotype-shared blood transfusions in combinations where the H2 type of the organ donor differed from that of the transfusion donor are less efficient in inducing prolongation of graft survival. CONCLUSIONS: These results demonstrate that haplotype-shared blood transfusions can induce a significantly prolonged survival of cardiac allografts in F1 mice. The immunogenetic studies suggest that presentation of alloantigen-derived peptides in the context of self MHC (the indirect pathway of allorecognition) is essential for the beneficial effect of haplotype-shared blood transfusions.

Animals↗

Humoral immune responses to adenovirus vectors in the brain.

We have investigated the humoral immune response to E1-deleted adenovirus vectors encoding the lacZ gene introduced into the brains of mice. Injection of these non-replicating vectors into the brain induced systemic antibody production to adenovirus vectors in dose dependent manner. Apparent antibody production to beta-galactosidase, the product of the lacZ gene, was detected later than anti-adenovirus antibody. Neutralizing antibody was not detected. This study demonstrates that E1-deleted adenovirus vectors injected into the brain trigger humoral immune responses to the adenovirus and its gene products, but they are not sufficient to block the infection of cells by adenovirus upon repeat injection.

Adenoviridae↗