Clinicopathologic features of retinoblastoma after primary chemoreduction

BACKGROUND: Cytotoxic T cells can induce target cell lysis and apoptosis by different pathways. The interactions of CD95 antigen (Fas) with its ligand (CD95L) and of tumor necrosis factor (TNF)-alpha with its receptor (TNF-R1) lead to apoptotic cell death. Recently, conflicting studies have been published concerning the expression and the role of CD95L in allograft rejection and tolerance. METHODS: In this study, the intragraft expression of CD95/CD95L and TNF-alpha and the frequency and distribution of apoptotic cells were compared in a model of heterotopic cardiac allograft in the rat in which recipients were either not treated (acute rejection) or pretreated with donor-specific blood transfusion (tolerant). RESULTS: In the acutely rejected allografts, a peak in the expression of CD95L and TNF-alpha and in the number of apoptotic cells was observed during the first week after transplantation; apoptotic cells were confined to graft-infiltrating cells. In the tolerated allografts, however, levels of graft-infiltrating cell apoptosis and CD95L and TNF-alpha expression during the same period of time were dramatically lower. The expression of Fas was constitutive and was not modulated during acute rejection or tolerance. CONCLUSION: This down-regulation of CD95L and TNF-alpha in allografts rendered tolerant by donor-specific transfusion suggests a role for apoptosis-inducing pathways in acute allograft rejection.     

Abdominal findings in AIDS-related pulmonary tuberculosis correlated with associated CD4 levels

BACKGROUND: There is evidence that inducible nitric oxide (NO) may be directly related to the process of allograft rejection. Because of its strong pulmonary vasodilatory activity, inhaled NO (INO) has recently been used as a therapeutic option for allograft dysfunction after lung transplantation. The action of inducible NO and inhaled NO seems contradictory for preserving posttransplantation pulmonary allograft function. INO used for lung transplant recipients may actually enhance acute allograft rejection. We studied the effect of INO on acute allograft rejection with a rat pulmonary allograft model. METHOD: A total of 24 left lung allotransplantations were performed from Lewis donors into F344 recipients. Animals were divided into two groups and inhaled either room air alone or 20 ppm NO with room air in a closed chamber immediately after transplantation until rats were killed on days 7 and 14. During observation, NO uptake was monitored by measuring serum NO2-/NO3- level. Acute rejection was evaluated by use of a semiquantitative radiographic scoring method (aeration score: 0 to 6, opaque to normal appearance) and rejection score (0 to 4, no sign of rejection to diffuse mononuclear infiltration). RESULTS: Markedly elevated serum NO2-/NO3- levels were observed in the NO inhalation group compared with levels in the normal air inhalation control group (110.8 +/- 25.3 vs 16.3 +/- 4.0 micromol/L/ml on day 7, p < 0.01; 107.0 +/- 30.9 vs 16.8 +/- 4.8 micromol/L/ml on day 14, p < 0.01). However, no positive effect of INO on acute rejection was found histologically or radiographically. CONCLUSION: The effect of INO on acute rejection is likely so minimal as not to be clinically relevant.     

Immunosuppression by inhibition of cellular adhesion mediated by leukocyte function-associated antigen-1/intercellular adhesion molecule-1 in murine cardiac transplantation

BACKGROUND: Donor alloantigen-specific tolerance to vascularized allografts can be induced by several treatments, but the immunological mechanism(s) of these effects remain unclear. One hypothesis is that allograft unresponsiveness is correlated with a shift in the pattern of expression of the T helper 1 versus T helper 2 T-cell cytokines. We report here an extensive analysis of murine cardiac allografts, during normal first set rejection and in mice treated with anti-adhesion molecule monoclonal antibodies (mAbs), a regimen that results in prolonged unresponsiveness. METHODS: A combination of immunohistochemical staining with a panel of mAbs, and in situ hybridization with a panel of digoxigenin-labeled riboprobes, was performed on frozen-tissue sections of cardiac allografts. RESULTS: In several strain combinations, injection of anti-leukocyte function-associated antigen-1 and anti-intercellular adhesion molecule-1, from day 0 to day 6 after transplantation, results in significant long-term survival. Examination of tolerated cardiac allografts by in situ hybridization and immunohistochemical staining shows an altered cytokine expression pattern, although the frequency of CD3 and CD4 cells is not dramatically reduced. These allografts show a decreased frequency of interferon-gamma and interleukin (IL)-2-expressing cells and a slightly increased frequency of cells expressing IL-4 and IL-10, compared with unmodified acute rejection. A direct role of these changes in T-cell cytokine expression is demonstrated by reversal of tolerance induction and rejection of the allograft by in vivo injection of either anti-IL-10 or anti-IL-4 mAb. CONCLUSIONS: Although there are significant differences in the frequency of different cellular subsets and patterns of cytokine gene expression, these differences are quantitatively subtle, suggesting a delicately balanced immune response that can develop a pattern of specific unresponsiveness, with relatively minor alterations in the specific T-cell response.     

Free radical-mediated tissue injury in acute lung allograft rejection and the effect of superoxide dismutase

BACKGROUND: The role of monocytes and neutrophils is crucial during acute allograft rejection. They have the capacity to generate toxic reactive oxygen intermediates in response to specific agonists that may act as tissue destructive molecules. We examined the possibility of reactive intermediate-mediated tissue injury in acute lung allograft rejection, as well as the effect of superoxide dismutase. METHODS: Allogenic (Brown Norway to F344) or syngenic (F344 to F344) rat left-lung transplantation was performed. Generation of reactive oxygen intermediates in peripheral blood was evaluated by the method of luminol-dependent chemiluminescence. Cell membrane phospholipid peroxidation in the graft was measured as malondialdehyde concentration. The third group of animals having allografts received bovine erythrocyte superoxide dismutase (5,000 U/kg intravenously every 12 hours after transplantation). RESULTS: Relative chemiluminescence response in the allograft recipient to normal F344 was elevated on postoperative day 1 (257%), then decreased slightly on day 3 (156%) and was elevated again on day 7 (560%) as the process of rejection progressed. Allograft tissue malondialdehyde levels (248.37 +/- 112.35 nM/whole lung, n = 6; p < 0.05 by Student's t test) were higher than isograft levels (139.29 +/- 35.93 nM/whole lung, n = 6) on day 7. Superoxide dismutase treatment significantly ameliorated the histologic degree of rejection on day 7. CONCLUSIONS: These results demonstrate the tissue destructive activity of reactive oxygen intermediates during lung allograft rejection. To scavenge free radicals may be a useful therapeutic modality in the management of acute lung allograft rejection.     

Tumor necrosis factor-beta is associated with thymic apoptosis during acute rejection

BACKGROUND: Intrathymic events undergoing allograft rejection remain undefined. The present study investigated the role of tumor necrosis factor-beta on acute thymic involution in rat hepatic allograft recipients during rejection. METHODS: Apoptosis and cellular phenotypic changes in the thymus were studied after hepatic transplantation. RESULTS: Thymocytes in both the medulla and cortex were sparse during acute rejection. Phenotypically, CD4+CD8+ T cells decreased significantly, whereas there were relative increases in CD4-CD8-, CD4+CD8-, and CD4-CD8+ T cells in untreated allograft recipients. Additionally, thymic apoptosis was found by in situ DNA end labeling and electron microscopy. Apoptotic cells were predominantly distributed in the cortex. Biologic lymphotoxin (tumor necrosis factor-beta)/tumor necrosis factor-alpha cytotoxic activity in the serum was significantly increased in untreated hepatic allograft recipients. Tumor necrosis factor-beta mRNA was detected in untreated allograft livers, and intraperitoneal administration of recombinant human tumor necrosis factor-beta induced extensive apoptosis of thymocytes in vivo. In contrast, no significant thymic involution was observed in donor-specific blood transfusion-treated allograft and isograft recipients. Intraperitoneal administration of rabbit anti-human tumor necrosis factor-beta polyclonal antibody or recombinant human interleukin-10 inhibited thymic apoptosis in untreated hepatic allograft recipients. CONCLUSIONS: Allograft rejection, but not donor-specific transfusion-induced immunologic unresponsiveness, is associated with thymic involution, a process that may be mediated by tumor necrosis factor-beta.     

Primary immunosuppression with mycophenolate mofetil and antithymocyte globulin for kidney transplant recipients of a suboptimal graft

BACKGROUND: In renal transplantation the beneficial immunosuppressive effects of cyclosporin (CsA) may be curtailed by its nephrotoxicity, specially in patients receiving a cadaveric allograft from suboptimal donors or at risk of delayed graft function. Mycophenolate mofetil (MMF) and antithymocyte globulin (ATG) have each demonstrated to be potent immunosuppressants in renal transplantation. In a prospective analysis we have studied the results at 6 months of the combination of MMF, ATG and low-dose steroids in patients with low immunological risk receiving a first cadaveric renal allograft from a suboptimal donor or at risk of delayed graft function. METHODS: Patients with preformed reactive antibodies < 500% receiving a first graft from a suboptimal donor (age > or = 40 years, non-heart-beating, acute renal failure, arterial hypertension) or at risk of delayed graft function (cold ischaemia time > or = 24 h) were eligible for this open single-arm pilot trial. From September 1996 to March 1997 we recruited 17 patients. They were treated with MMF 2 g p.o. preoperatively, and after transplantation at 3 g/day; rabbit ATG i.v. at 2 mg/kg preoperatively, and 1.5 mg/kg/day the first day after transplantation, followed by four doses of 1 mg/kg on alternate days; prednisone was given at 0.25 mg/kg/day and reduced progressively to 0.1 mg/kg/day at 3 months. Primary outcomes were incidence of biopsy-proven acute rejection, delayed graft function, opportunistic infections, graft and patient survival, and the need for introduction of CsA treatment. RESULTS: delayed graft function occurred in two cases (12%). Four of 17 patients (24%) had a biopsy-proven acute rejection (2 grade I and 2 grade II) within the first 3 months after transplantation. CsA was added in two cases with grade II biopsy-proven acute rejection, and in one with grade I biopsy-proven acute rejection. In one patient MMF was replaced by CsA because of gastrointestinal intolerance. Mean serum creatinine 6 months after transplantation was 159+/-59 micromol/1. Cytomegalovirus tissue invasive disease occurred in one patient (6%). At 6 months follow-up all patients are alive with functioning allografts. CONCLUSIONS: These preliminary results suggest that in low-immunological-risk patients who receive a suboptimal renal allograft or at risk of delayed graft function, the combination of MMF, ATG, and steroids is an efficient immunosuppressive regime that may avoid the use of CsA in 70% of the recipients.     

Blockade of the CD40-CD40 ligand pathway potentiates the capacity of donor-derived dendritic cell progenitors to induce long-term cardiac allograft survival

BACKGROUND: Failure of costimulatory molecule-deficient donor dendritic cells (DCs) to induce indefinite allograft acceptance may be a result of the 'late" up-regulation of these molecules on the DCs after interaction with host T cells. Ligation of CD40 on antigen-presenting cells by its cognate ligand CD40L is thought to induce expression of CD80 (B7-1) and CD86 (B7-2). We examined the influence of anti-CD40L monoclonal antibody (mAb) on the capacity of donor-derived DC progenitors to induce long-term allograft survival. METHODS: High purity DC progenitors were grown from B10 (H2b) mouse bone marrow in granulocyte-macrophage colony-stimulating factor and transforming growth factor beta1 (TGFbeta1). Mature DC were propagated in granulocyte-macrophage colony-stimulating factor and interleukin-4. Their phenotype was characterized by flow cytometric analysis and their function by mixed leukocyte reactivity. Anti-donor cytotoxic T lymphocyte activity in grafts and spleens of vascularized heart allograft recipients was also assessed. RESULTS: The TGFbeta3-cultured cells were (1) DEC 205-positive, MHC class II-positive, CD80dim, CD86dim, and CD40dim, (2) poor stimulators of naive allogeneic T-cell proliferation, and (3) able to prolong significantly B10 cardiac allograft survival in C3H (H2k) recipients when given (2 x 10[6] i.v.) 7 days before organ transplantation (median survival time [MST] 26 days vs. 12 days in controls, and 5 days in interleukin-4 DC-treated animals). Their allostimulatory activity was further diminished by addition of anti-CD40L mAb at the start of the mixed leukocyte cultures. Anti-CD40L mAb alone (250 microg/mouse, i.p.; day -7) did not prolong cardiac graft survival (MST 12 days). In contrast, TGFbeta-cultured DCs + anti-CD40L mAb extended graft survival to a MST of 77 days, and inhibited substantially the anti-donor cytotoxic T lymphocyte activity of graft-infiltrating cells and host spleen cells assessed 8 days after transplant. CONCLUSIONS: The CD40-CD40L pathway appears important in regulation of allogeneic DC-T-cell functional interaction in vivo; its blockade increases markedly the potential of costimulatory molecule-deficient DCs of donor origin to induce long-lasting allograft survival.     

Expression of interleukin-6 in association with rat lung reimplantation and allograft rejection

Organ transplantation has become a therapeutic option for the replacement of malfunctioning tissues and organs. Since the advent of the first combined heart-lung transplant in 1981, there has been a rapid growth in the popularity of lung transplantation for a number of end-stage pulmonary disorders. Interestingly, these lung transplant patients experience more complications of acute and chronic allograft rejection compared with recipients of other solid organs. These episodes of rejection are related to a complex series of events that depend on the interaction of many cells and soluble mediators leading to cellular and tissue injury. The histopathology of lung allograft rejection has been actively studied and is associated with the sequestration of activated mononuclear phagocytes, T and B lymphocytes. These cells secrete a number of soluble mediators, that is, cytokines, that participate in the evolution of the immune response via autocrine, paracrine, or endocrine mechanisms. The interaction of cytokines with their targets leads to cellular activation, proliferation, and differentiation. In this study, we postulated that interleukin-6 (IL-6) may have a central role in the pathogenesis of acute lung allograft rejection. To test this hypothesis, we employed an unmodified RT1-incompatible rat lung allograft model and assessed the time course and major tissue compartment(s) of IL-6 production during the evolution of lung allograft rejection. The expression and production of IL-6 during the pathogenesis of lung allograft rejection was measured at the whole-animal, organ, cellular, and molecular levels. The expression of IL-6 was found to be bimodal in character, initially related to the reimplantation response and finally to the maximal allograft rejection.(ABSTRACT TRUNCATED AT 250 WORDS)     

The Cdc6p nucleotide-binding motif is required for loading mcm proteins onto chromatin

We propose that a novel mechanism of hepatocyte apoptosis, involving a cooperative interaction between CD40 and Fas, is involved in the hepatocyte loss of chronic liver allograft rejection. We detected increased hepatocyte expression of Fas, Fas ligand (FasL), and CD40 associated with dropout of centrilobular (acinar zone 3) hepatocytes in chronic allograft rejection. Expression of CD40 ligand (CD40L) was also increased but was largely restricted to CD68(+) macrophages. A functional role for CD40 and Fas in hepatocyte apoptosis was demonstrated in vitro using primary human hepatocytes and the HepG2 cell line in both of which apoptosis was induced, not only by cross-linking Fas directly but also via CD40 activation. Our data suggest that CD40 activation induces apoptosis via Fas because (a) ligation of CD40 upregulated hepatocyte FasL expression, and (b) apoptosis induced via activation of CD40 was prevented by a neutralizing monoclonal antibody to FasL. Thus, CD40 engagement triggers apoptosis of human hepatocytes and might amplify Fas-dependent hepatocyte apoptosis in chronic rejection and other inflammatory liver diseases in which Fas-mediated apoptosis is involved.     

Delayed function reduces renal allograft survival independent of acute rejection

BACKGROUND: Mechanisms by which delayed allograft function reduces renal allograft survival are poorly understood. This study evaluated the relationship of delayed allograft function to acute rejection and long-term survival of cadaveric allografts. METHODS: 338 recipients of cadaveric allografts were followed until death, resumption of dialysis, retransplantation, loss to follow-up, or the study's end, which ever came first. Delayed allograft function was defined by dialysis during the first week following transplantation. Multivariate Cox proportional hazards survival analysis was used to assess the relationship of delayed allograft function to rejection and allograft survival. RESULTS: Delayed allograft function, recipient age, preformed reactive antibody levels, prior kidney transplantation, recipient race, rejection during the first 30 days and rejection subsequent to 30 days following transplantation were predictive of allograft survival in multivariate survival models. Delayed allograft function was associated with shorter allograft survival after adjustment for acute rejection and other covariates (relative rate of failure [RR]+1.72 [95% CI, 1.07, 2.76]). The adjusted RR of allograft failure associated with any rejection during the first 30 days was 1.99 (1.23, 3.21), and for rejection subsequent to the first 30 days was 3.53 (2.9 08, 6.00). The impact of delayed allograft function did not change substantially (RR=1.84 [1.15, 2.95]) in models not controlling for acute rejection. These results were stable among several subgroups of patients and using alternative definitions of allograft survival and delayed allograft function. CONCLUSIONS: This study demonstrates that delayed allograft function and acute allograft rejection have important independent and deleterious effects on cadaveric allograft survival. These results suggest that the effect of delayed allograft function is mediated, in part, through mechanisms not involving acute clinical rejection.     

The influence of endodontic infection on periodontal status in mandibular molars

We investigated the pathogenesis of chronic allograft rejection in mouse cardiac allografts. Long-term survival occurred after administration of monoclonal antibody to CD4 or CD40-ligand (CD40L) plus donor cells. Both treatments induced permanent graft survival, but, in contrast to transplants in mice treated with CD4 monoclonal antibody, grafts in mice treated with CD40L monoclonal antibody lacked evidence of chronic rejection, including transplant arteriosclerosis. Freedom from chronic rejection in the group treated with CD40L monoclonal antibody correlated with vascular expression of the 'protective' genes heme oxygenase-1 (HO-1), Bcl-xL and A20. Moreover, arteriosclerosis was induced in allografts in immunoglobulin-deficient mice by antibody transfer only when the transfer was done before expression of protective genes. A direct role for protective gene expression in endothelial cells was demonstrated by in vitro experiments in which induction of HO-1 or Bcl-xL suppressed alloantibody-stimulated endothelial activation. Finally, induction of HO-1 in vivo protected allografts against chronic injury. These data show a role for protective genes in the prevention of chronic rejection, and indicate new approaches to protect grafts against development of transplant arteriosclerosis.     

Expression of granzyme B during primary cytomegalovirus infection after renal transplantation

CD8+ T cells employ granzyme B (GrB) to induce apoptosis in target cells. Increased expression of GrB has been put forward as a diagnostic marker in transplant rejection and viral infection. Three-color flow cytometric analysis revealed that peripheral blood CD8+ T lymphocytosis during primary cytomegalovirus infection after renal transplantation resulted from expansion of a CD8+GrB+CD62L+ T cell subset that was almost absent during stable transplant function or acute rejection. This expansion coincided with a temporary increase in systemic soluble GrB (sGrB) levels. No such increase was observed during stable transplant function or acute rejection. Thus, the primary immune response to cytomegalovirus infection is accompanied by appearance of CD8+GrB+CD62L+ T cells and increased sGrB levels in the peripheral blood compartment. Determination of the latter may provide a novel approach for monitoring viral infections.     

Soluble and cell surface ICAM-1 as markers for disease activity in multiple sclerosis

Infiltration of a transplanted organ by host lymphoid cells is the hallmark of acute rejection. However, after intestinal transplantation, physiological lymphocyte migration may lead to host cell infiltration of the graft even in the absence of rejection. It is unclear whether this lymphocyte migration also involves the intraepithelial compartment of the graft or whether infiltration there is indicative of acute rejection. We demonstrate here that host cell infiltration of the intestinal mucosa occurs both during acute rejection of a small bowel allograft and, to a lesser extent, when rejection is prevented by immunosuppression with FK506. The infiltrating host cells consisted of CD3+ T cells with a predominant CD4-CD8+ phenotype resembling intraepithelial lymphocytes (IELs). Functional studies showed that the nonspecific cytolytic activity of IELs was not affected by acute rejection or by immunosuppression with FK506. These findings indicate that host cell infiltration of the intestinal mucosa does not connote an ongoing acute rejection. Furthermore, the decreased mucosal barrier function during acute rejection of intestinal allgrafts is probably not due to impaired cytolytic activity of IELs.     

Indefinite islet allograft survival in mice after a short course of treatment with anti-CD45 monoclonal antibodies

BACKGROUND: Although islet cell transplantation is considered an ideal form of endocrine replacement for type I diabetes, clinical application in humans is still not feasible. New immunosuppressive strategies are clearly needed to control inexorable rejection. CD45 is a family of transmembrane protein tyrosine phosphatases critically involved in the regulation of lymphocyte activation signals. Anti-CD45RB monoclonal antibody can prevent rejection of murine renal allografts. METHODS: Here, we examine the consequences of targeting CD45 in murine islet cell transplantation. Diabetic mice recipients received islet allografts under the kidney capsule and were divided into seven groups. Recipients received no treatment (controls) or anti-CD45RB monoclonal antibody (mAb; MB23G2 or C363.16A) at different dosages and treatment intervals. RESULTS: All untreated control animals lost islet function, becoming hyperglycemic within 10-17 days after transplantation. Animals treated with either anti-CD45RB mAb showed a significant prolongation of islet allograft survival when compared with controls. Anti-CD45RB MB23G2 at 100 microg/day, given on days -1, 0, and 5 was particularly effective, inducing indefinite islet allograft survival in 60% of recipients. CONCLUSIONS: These results indicate that anti-CD45 mAbs are potent immunomodulatory agents, able to sustain indefinite islet allograft function after a short treatment course in the highly immunogenic model of islet transplantation.