Biomedical subjects

P J Morris

Publications and source records attributed to P J Morris.

At least 19 recordsLinked to original sources

PubMed2001

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↗

PubMed2001

Donor cytokine genotype influences the development of acute rejection after renal transplantation.

BACKGROUND: Acute allograft rejection remains an important cause of morbidity after kidney transplantation, and has been shown to be a crucial determinant of long-term graft function. Although rejection is mediated by recipient lymphocytes, both donor and recipient factors contribute to the local environment that influences the nature, severity, and duration of the rejection response. Cytokines are a major determinant of this milieu, and this study sought to explore the impact of donor cytokine and cytokine receptor gene polymorphisms on acute rejection after renal transplantation. METHODS: A total of 145 cadaveric renal allograft donors were selected for analysis according to the presence or absence of graft rejection in the first 30 days after transplantation. DNA was genotyped for 20 polymorphisms in 11 cytokine and cytokine receptor genes using the polymerase chain reaction with sequence specific primers. Associations were assessed using contingency table analysis and the chi2 test, using a two-set design. RESULTS: A polymorphism at position -174 of the donor IL-6 gene was associated with the incidence (P=0.0002) and severity (P=0.000007) of recipient acute rejection. This finding was independent of HLA-DR matching. Acute rejection was not influenced by recipient IL-6 genotype, or by donor-recipient matching of IL-6 genotype. CONCLUSION: This study identifies donor IL-6 genotype as a major genetic risk factor for the development of acute rejection after renal transplantation. This provides evidence that donor-derived cytokines play a major role in determining outcome after transplantation, and will contribute to the development of therapeutic algorithms to predict individuals at particularly high risk of acute rejection.

Acute Disease↗

PubMed2001

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↗

PubMed2001

Distribution of upper limb skin cancers in relation to arteriovenous fistula side in renal transplant recipients.

BACKGROUND: Renal transplant patients have an increased incidence of skin cancers, predominantly on sun-exposed surfaces. Clinical observation identified some patients with an increased number of viral warts, keratoses, and skin malignancies on the side of the arteriovenous fistula. METHODS: In a population of 980 patients who underwent transplantation in Oxford, we identified 68 patients with known fistula site who had developed cutaneous malignancies on the upper limbs. We compared the distribution of skin malignancies in relation to the side of the arteriovenous fistula with regard to histologically confirmed Bowen's disease, squamous cell carcinoma, basal cell carcinoma, and keratoacanthoma. RESULTS: No significant difference was found between the distribution of skin cancers, total malignancies or subgroups, in the fistula limbs compared with the nonfistula limbs. CONCLUSION: We have been unable to demonstrate that the presence of an arteriovenous fistula predisposes to the development of cutaneous malignancies.

Arm↗

PubMed2001

Chemical immobilization of felids, ursids, and small ungulates.

Private ownership of wild animals is on the rise. With the advent of potent new sedative agents, many practitioners now receiving these cases have the means to increase the safety and effectiveness of chemical immobilization in many wildlife species. Chemical immobilization is actually the induction of anesthesia. In many cases, induction alone suffices to achieve some management or medical goal, whereas in other cases, maintenance anesthesia is required. One quickly realizes that once these species are induced, maintenance anesthesia is often familiar, based on experiences with domestic animals that bear close similarity to the species discussed in this chapter. Induction and recovery of wild animals requires special attention to details to prevent "fight or flight" responses from marring the success of a sedation procedure. Although potent novel drugs allow veterinarians to expand their practice horizons, it is vital to evaluate legal and safety issues thoroughly before engaging in the care of wildlife species on a regular basis.

Anesthesia↗

PubMed2000

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↗

PubMed2000

The impact of recipient cytokine genotype on acute rejection after renal transplantation.

BACKGROUND: Acute allograft rejection remains an important cause of morbidity after kidney transplantation, and has been shown to be a crucial determinant of long-term graft function. As cytokines are major regulators of the immune system, genetic variation in cytokine production or activity may influence susceptibility to acute rejection. This study sought to determine the impact of recipient cytokine and cytokine receptor polymorphisms on acute rejection after renal transplantation. METHODS: A total of 209 cadaveric renal transplant recipients were selected for analysis according to the presence or absence of graft rejection in the first 30 days after transplantation. DNA was genotyped for 22 polymorphisms in 11 cytokine and cytokine receptor genes using the polymerase chain reaction with sequence specific primers. Results were stratified by incidence and severity of rejection, and by HLA-DR mismatching. RESULTS: No association between any polymorphism and the incidence or severity of acute rejection was detected. In particular, no association was seen with tumor necrosis factor or interleukin-10 genotype, either alone or in combination. CONCLUSIONS: We have failed to demonstrate any association between recipient cytokine genotype and acute rejection after cadaveric renal transplantation. Although more extensive studies may disprove these findings, it would seem premature to use recipient cytokine genotyping to predict transplant outcome, or to guide immunosuppressive therapy after transplantation.

Acute Disease↗

PubMed2000

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↗

PubMed2000

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↗

PubMed2000

Detection of HLA-specific IGG antibodies using single recombinant HLA alleles: the MonoLISA assay.

BACKGROUND: Because of the presence of confounding antigens, the assignment of HLA antibody specificity is difficult in highly sensitized patients, and the definition of an acceptable HLA mismatch requires a significant workload per patient. We describe a new ELISA method, monoLISA, for detection of immunoglobulin (Ig)G HLA antibody using single recombinant HLA class I monomers bound to microtiter plates. METHODS: HLA-A2 and -B8 monomers were synthesized and used as screening targets for 85 sera from renal patients. The sera contained various IgG and IgM HLA-specific antibodies, including anti-A2 and anti-B8,defined in a conventional complement-dependent cytotoxicity test (CDC). Investigations were performed to determine possible effects on antibody binding of differential monomer peptide presentation as well as lack of glycosylation. RESULTS: A good correlation was found between CDC-defined specificities and the reactivity observed with HLA monomers. MonoLISA attained means of 100% sensitivity and 92.5% specificity compared with CDC. Neither the presence of different peptides, nor the absence of glycosylation of the monomer affected the ability of monoLISA to detect antibody. CONCLUSION: This study demonstrates that the mono-LISA method for HLA antibody detection is valid. Because this has the potential to reduce the work involved in screening sensitized patients awaiting transplantation for HLA antibodies, resources aimed at increasing the number of constructed monomers would be well targeted.

Alleles↗

PubMed2000

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↗

PubMed2000

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↗

PubMed2000

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↗

PubMed2000

p53 codon 72 polymorphism and susceptibility to skin cancer after renal transplantation.

BACKGROUND: Infection with human papillomavirus (HPV) is an important risk factor for the development of skin cancer after renal transplantation. It has recently been suggested that degradation of the tumor suppressor gene p53 is an important mechanism for human papillomavirus-induced carcinogenesis. A common genomic polymorphism occurs at codon 72 of the p53 gene, and in vitro the codon 72Arg variant appears to be particularly susceptible to degradation. METHODS: To test the hypothesis that this polymorphism predisposes to the development of human papillomavirus-associated tumors, we studied p53 codon 72 genotype in 222 long-term survivors of renal transplantation, of whom 55 had developed at least one skin tumor. RESULTS: No differences in allele or genotype frequency were detected between individuals who had or had not developed skin tumors after transplantation, or any subgroup thereof. CONCLUSIONS: The p53 codon 72Arginine allele does not confer susceptibility to the development of skin tumors after renal transplantation.

Alleles↗

PubMed2000

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↗

PubMed2000

Differential role for competitive reverse transcriptase-polymerase chain reaction and intracellular cytokine staining as diagnostic tools for the assessment of intragraft cytokine profiles in rejecting and nonrejecting heart allografts.

The early and reliable diagnosis of allograft rejection is a difficult task and the assessment of cytokine expression in the grafts can be a helpful parameter. We have compared competitive reverse transcriptase-polymerase chain reaction (RT-PCR) with intracellular cytokine staining by flow cytometry as tools to measure cytokine expression in rejecting and nonrejecting murine cardiac allografts. Both techniques gave comparable results for cytokine expression in rejecting allografts and syngeneic controls. Grafts from mice pretreated with anti-CD4 antibody and donor-specific blood transfusion showed a marked reduction in cytokine expression, as assessed by competitive RT-PCR, even though a cellular infiltrate was present in the graft. In contrast, the cytokine production measured by intracellular cytokine staining of the isolated graft-infiltrating cells was high and exceeded even that of the rejecting allografts. We conclude that intracellular cytokine staining of graft-infiltrating leukocytes by flow cytometry does not necessarily reflect accurately the cytokine milieu in the graft. This technique might therefore have a limited clinical application in contrast to competitive RT-PCR for the differentiation between graft acceptance and graft rejection.

Animals↗

PubMed2000

Evidence that non-deletional mechanisms are responsible for inducing and maintaining unresponsiveness after intrathymic injection of non-professional antigen presenting cells.

INTRODUCTION: Intrathymic inoculation of donor alloantigen and concomitant immunosuppressive treatment can induce immune unresponsiveness to alloantigen. To examine the role of non-deletional mechanisms in the development of unresponsiveness, fractionated splenocytes were injected into only 1 lobe of the thymus. METHODS AND RESULTS: Untreated CBA (H2(k)) mice or controls pre-treated with anti-CD4 monoclonal antibody alone (on Day -28 and -27 relative to transplantation) acutely rejected C57BL/10 (H2(b)) cardiac allografts. Intrathymic inoculation of unfractionated splenocytes, resting B (rB) cells, or dendritic cells into both thymic lobes with the antibody resulted in indefinite survival of cardiac allografts. In contrast, when donor rB cells or dendritic cells were delivered into a single lobe of the thymus with the antibody, only rB cells induced indefinite prolongation of graft survival; unfractionated splenocytes or dendritic cells were markedly less effective. Mice that had 1 of the 2 thymic lobes removed were able to reject grafts even when treated with the antibody 27 days before transplantation. Therefore, T-cell export from 1 thymic lobe was sufficient to induce graft rejection. Finally, adoptive transfer of splenocytes from mice with long-term surviving primary grafts resulting from the intrathymic injection of rB cells significantly prolonged a graft from the same donor strain in a naive syngeneic recipient. CONCLUSION: Taken together, these data suggest that regulatory mechanisms generated by intrathymic injection of a non-professional antigen presenting cell, in this study donor rB cells, suppressed the rejection response mediated by T cells exported from the uninjected lobe.

Animals↗

PubMed2000

Development of a combined cardiac and aortic transplant model to investigate the development of transplant arteriosclerosis in the mouse.

BACKGROUND: The degree of transplant arteriosclerosis in murine cardiac allografts is difficult to assess. Aortic allografts represent an alternative model for evaluating the impact of novel transplant strategies on transplant arteriosclerosis in which the vascular changes can be quantified easily. However, it remains controversial as to whether vascular lesions seen in this model are equivalent to those that develop in solid-organ transplants. The aim of this study was to develop a model of combined cardiac and aortic transplantation to allow more precise quantification of transplant arteriosclerosis and to establish a correlation between the lesions that develop in the 2 types of graft. METHODS: CBA (H2(k)) recipients received a C57BL/10 (H2(b)) cervical cardiac allograft on Day 0 and a C57BL/10 (H2(b)) abdominal aortic allograft on Day 1. Recipients were treated with anti-CD154 mAb (MR1) on Days 0, 2, and 4. We performed histology and morphometric measurements for both grafts 30 days after transplantation. RESULTS: We observed significant intimal proliferation in both the cervical cardiac and abdominal aortic allografts from recipients treated with anti-CD154 mAb (heart, 64% +/- 9%; aorta, 67% +/- 8%; n = 5). Abdominal aortic grafts transplanted alone into anti-CD154-treated recipients developed a degree of transplant arteriosclerosis equivalent to that seen in the aortic grafts of the combined group (aorta alone, 68% +/- 9%, vs aorta + heart, 67% +/- 8%; n = 5). CONCLUSIONS: This combined cardiac and aortic transplant model permitted quantitative assessment of transplant arteriosclerosis while monitoring graft survival by cardiac palpation. Furthermore, development of transplant arteriosclerosis was equivalent in abdominal aortic allografts either in the presence or absence of an additional solid- organ transplant.

Animals↗