Biomedical subjects

Adriana Zeevi

Publications and source records attributed to Adriana Zeevi.

At least 19 recordsLinked to original sources

PubMed2007

Persistent donor-specific alloreactivity may portend delayed liver rejection during drug minimization in children.

Immunoreactivity, immunosuppression requirement and liver graft function was assessed serially for its relationship to delayed/recurrent acute cellular rejection (ACR) after the first 60 days in 36 pediatric primary liver transplant (LTx) recipients. Subjects were classified as rejectors (n=20) or Non-Rejectors (n=16) based on the presence/absence of biopsy-proven ACR in the first 60 days. All children received anti-lymphocyte induction and steroid-free Tacrolimus or Sirolimus monotherapy, as reported previously. Median age was 4 years (0.45-18) and follow-up was 570 days (106-1144). Compared with non-rejectors, rejectors 1. took significantly longer to achieve reduced donor-specific alloreactivity by MLR (p=0.049), and "low" TAC/SRL whole blood requirements defined as TAC levels < or = 8 ng/ml (p=0.0048), 2. experienced significantly greater variation in time to achieve reduced donor-specific immunoreactivity (SEM 0.8 vs 3.85, p=0.0048), and 3. experienced greater ACR incidence during minimization of immunosuppression (35% versus 6%, p=0.032). Serial monitoring of immunoreactivity may increase the safety with which immunosuppression is minimized in pediatric LTx.

Adolescent↗

PubMed2006

Pancreas transplantation under alemtuzumab (Campath-1H) and tacrolimus: Correlation between low T-cell responses and infection.

BACKGROUND: Alemtuzumab induction and tacrolimus-based immunosuppression has been effective in pancreas transplantation. Despite the encouraging results of this minimalistic approach to immunosuppression, infection still remains a significant cause of morbidity. The Cylex ImmuKnow [corrected] assay was used in this study to compare pancreas recipient clinical states (stable, rejection, infection) with T cell responses. METHODS: Blood samples were taken from pancreas recipients pretransplant and at approximately three-month intervals posttransplant for analysis of T cell responses. When possible, T cell responses were also quantified during changes in clinical status (infection or rejection). RESULTS: A range between 100-300 ng/ml adenosine triphosphate (ATP) was found in stable patients (mean 194+/-123, n = 51) with good graft function and no infection or rejection. A low T cell response was highly correlated with infectious states. The fourteen patients with infections/posttransplant lymphoproliferative disease had a mean ATP of 48 ng/ml. Risk hazard analysis showed that patients with ATP levels <100 ng/ml were four to seven times more susceptible to infection compared to stable patients. Four patients with rejection showed a T cell response of 550 ng/ml ATP, which was statistically significant compared to stable patients, although the sampling numbers (9) were too small to be conclusive. CONCLUSION: The Cylex ImmuKnow [corrected] assay is a valuable tool to more precisely modulate immunosuppression in pancreas transplant patients. In particular, the assay is extremely useful in detecting overly immunosuppressed patients vulnerable to infections.

Adenosine Triphosphate↗

PubMed2006

Disparate distribution of 16 candidate single nucleotide polymorphisms among racial and ethnic groups of pediatric heart transplant patients.

BACKGROUND: Allograft failure in African-Americans remains higher than in Caucasians. Single nucleotide polymorphisms (SNPs) have been associated with altered allograft outcomes. METHODS: In this multi-center study we compared SNP frequencies in 364 pediatric heart recipients from three ethnic/racial groups: Caucasian (n = 243), African-American (n = 39), and Hispanic (n = 82). The target genes were: tumor necrosis factor-alpha, interleukin (IL)-10, IL-6, interferon (IFN)-gamma, vascular endothelial growth factor (VEGF), transforming growth factor-beta1, Fas, FasL, granzyme B, ABCB1, CYP3A5. RESULTS: Compared to Caucasians, African-Americans exhibited a higher prevalence of genotypes associated with low expression of IFN-gamma (24% vs. 45.7%, P < 0.001) and IL-10 (33% vs. 57.1%, P = 0.052). African-Americans also exhibited an increased prevalence of high IL-6 (82.9% vs. 38.1%; P < 0.001). VEGF -2578 C/C and -460 C/C genotypes were found more frequently in African-Americans and Hispanics as compared to Caucasians (P < 0.001). G/G genotype of Fas and T/T genotype of FasL were expressed more often by African-American recipients. The prevalence of Granzyme B (-295A/G) genotype was differentially distributed in the three groups. Compared with Caucasians, African-Americans were twice as likely to carry the ABCB1 2677 G/G genotype (78.6% vs. 33.7%, P < 0.0025), and they were more frequent carriers of the CYP3A5 *1/*1 genotype (35.7% vs. 0.6% in Caucasians and 7.2% in Hispanics; P < 0.001). CONCLUSION: African-Americans have a genetic background that may predispose to proinflammatory/lower regulatory environment, reduced drug exposure and immunosuppressive efficacy. In this ongoing multicenter study, these gene polymorphisms differences among ethnic/racial groups are being documented so that therapeutic strategies can be devised to optimize outcomes for pediatric transplant recipients.

Adolescent↗

PubMed2006

CTLA4-Ig-based conditioning regimen to induce tolerance to cardiac allografts.

BACKGROUND: Transplant rejection and toxicity associated with chronic immunosuppressive therapy remain a major problem. Mixed hematopoietic chimerism has been shown to produce tolerance to solid organ transplants. However, currently available protocols to induce mixed hematopoietic chimerism invariably require toxic pre-conditioning. In this study, we investigated a non-toxic CTLA4-Ig-based protocol to induce donor-specific tolerance to cardiac allografts in rats. METHODS: Fully mismatched, 4 to 6 week old ACI (RT1.A(a)) and Wistar Furth (RT1.A(u)) rats were used as cell/organ donors and recipients, respectively. Recipients were treated with CTLA4-Ig 2 mg/kg/day (on days 0, 2, 4, 6, 8), tacrolimus 1 mg/kg/day (daily, from days 0 to 9), and a single dose of anti-lymphocyte serum (10 mg) on day 10, soon after total body irradiation (300 cGy) and donor bone marrow (100 x 10(6) T-cell depleted cells) transplantation (BMT). Six weeks after BMT, chimeric animals received heterotopic heart transplants. RESULTS: Hematopoietic chimerism was 18.8 +/- 10.6% at day 30, and was stable (24 +/- 10%) at 1 year post-BMT; there was no graft versus host disease. Chimeric recipients (RT1.A(u)) permanently accepted (>360 days) donor-specific (RT1.A(a); n = 6) hearts, yet rapidly rejected (<9 days) third-party hearts (RT1.A(l); n = 5). Graft (heart) tolerant (>100 days) recipients accepted donor-specific secondary skin grafts (>200 days) while rejected the third-party skin grafts (<9 days). Lymphocytes of graft tolerant animals demonstrated hyporesponsiveness in mixed lymphocyte cultures in a donor-specific manner. Tolerant graft histology showed no obliterative arteriopathy or chronic rejection. CONCLUSIONS: The CTLA4-Ig based conditioning regimen with donor BMT produced mixed chimerism and induced donor- specific tolerance to cardiac allografts.

Abatacept↗

PubMed2006

Assessing relative risks of infection and rejection: a meta-analysis using an immune function assay.

BACKGROUND: Long-term use of immunosuppressants is associated with significant morbidity and mortality in transplant recipients. A simple whole blood assay that has U.S. Food and Drug Administration clearance directly assesses the net state of immune function of allograft recipients for better individualization of therapy. A meta-analysis of 504 solid organ transplant recipients (heart, kidney, kidney-pancreas, liver and small bowel) from 10 U.S. centers was performed using the Cylex ImmuKnow assay. METHODS: Blood samples were taken from recipients at various times posttransplant and compared with clinical course (stable, rejection, infection). In this analysis, 39 biopsy-proven cellular rejections and 66 diagnosed infections occurred. Odds ratios of infection or rejection were calculated based on measured immune response values. RESULTS: A recipient with an immune response value of 25 ng/ml adenosine triphosphate (ATP) was 12 times (95% confidence of 4 to 36) more likely to develop an infection than a recipient with a stronger immune response. Similarly, a recipient with an immune response of 700 ng/ml ATP was 30 times (95% confidence of 8 to 112) more likely to develop a cellular rejection than a recipient with a lower immune response value. Of note is the intersection of odds ratio curves for infection and rejection in the moderate immune response zone (280 ng/ml ATP). This intersection of risk curves provides an immunological target of immune function for solid organ recipients. CONCLUSION: These data show that the Cylex ImmuKnow assay has a high negative predictive value and provides a target immunological response zone for minimizing risk and managing patients to stability.

Graft Rejection↗

PubMed2006

Role of single nucleotide polymorphisms of cytokine genes in spontaneous preterm delivery.

Intra-amniotic infections are implicated in spontaneous preterm delivery (PTD). Certain genetic polymorphisms are associated with increased production of proinflammatory and/or decreased production of anti-inflammatory cytokines, thereby possibly promoting PTD. We determined the relationship between maternal and fetal cytokine gene polymorphisms with occurrence and severity of spontaneous PTD (PTD after spontaneous-onset preterm labor and/or preterm prelabor rupture of membranes) and their association with intrauterine inflammation and infection. DNA from buccal brushings of 80 preterm (gestation < 35 weeks) and 80 matched term mother-infant pairs was assayed for tumor necrosis factor alpha (TNF-alpha [-308G/A]), interferon-gamma (IFN-gamma [+874A/T]), interleukin-6 (IL-6 [-174C/G]), interleukin-10 (IL-10 [-1082G/A, -819C/T, -592C/A]), and transforming growth factor beta1 (TGF-beta1 [T/Ccodon10,G/Ccodon25]) by using polymerase chain reaction (PCR) with sequence-specific primers. The presence of histologic chorioamnionitis was determined for PTDs. Conditioned on maternal IFN-gamma genotypes, fetal high IFN-gamma producing allele (IFN-gamma[+874T]) was associated with spontaneous PTD (odds ratio = 2.3 [1.2-4.4]). Among preterm deliveries, maternal low TGF-beta1 (TGF-beta1 [codon10C]) producing genotypes correlated negatively with gestation. Fetal TNF-alpha (-308G) was significantly associated with histologic chorioamnionitis. Underlying genitourinary infections and/or inflammation were significantly associated with maternal and fetal IL-6 (-174G), fetal TNF-alpha (-308GG), and fetal IL-10 (-1082A). We conclude that certain fetal and maternal cytokine gene polymorphisms may be associated with occurrence and/or severity of spontaneous PTD and with intrauterine inflammation and infection.

Adult↗

PubMed2006

Heart and lung transplantation in children.

During the past two decades, several advances have resulted in marked improvement in medium-term survival for infants and children undergoing heart transplantation. Unfortunately, progress has been less dramatic in the field of lung and heart-lung transplantation, where there is little evidence of improved outcomes. The procedures remain palliative and all transplant recipients are at risk for the adverse effects of non-specific immunosuppression, including infections, lymphoproliferative disorders, and non-lymphoid malignancies. In addition, current immunosuppressive agents have narrow therapeutic windows and exhibit a wide array of organ toxicities, posing special challenges for the young patient who must endure life-long immunosuppression. New immunosuppressive regimens have lowered the rates of acute rejection but appear to have had relatively little impact on the incidence of chronic rejection, the principal cause of late graft loss. The ultimate goal is to induce a state of donor-specific tolerance, wherein the recipient will accept the allograft indefinitely without the need for long-term immunosuppression. This quest is currently being realised in animal models of solid organ transplantation, and offers great hope for children undergoing heart and lung transplantation in the future.

Adolescent↗

PubMed2006

Detection of CD8+ T cells sensitized to BK virus large T antigen in healthy volunteers and kidney transplant recipients.

BK virus (BKV) infections after renal transplantation are increasingly recognized. Development of immune monitoring strategies against BKV requires definition of antigenic epitopes. Hence, T cells from HLA-A02-positive healthy subjects and kidney transplant recipients were stimulated by BKV lysate pulsed on mature autologous dendritic cells and screened against four different T antigen peptides or against BKV lysate. IFN-gamma production was measured by ELISPOT assays. The peptide BKV362-371 (MLTERFNHIL) was naturally processed and recognized by five of six healthy subjects (39 +/- 11 IFN-gamma spots/100,000 cells) and five of seven kidney transplant recipients (21 +/- 12 IFN-gamma spots). Less frequent and weaker CD8+ T-cell responses were detected against three other peptides. Thus, BKV large T antigen is a target for CD8+ T-cell immunity. T-antigen-specific T-cytotoxic cells circulate in healthy blood donors, implying that transient expression of T antigen presumably occurs at sites of viral latency and helps maintain a constant pool of circulating CD8+ T memory cells.

Adult↗

PubMed2006

Impact of TGFbeta1 gene polymorphisms on acute and chronic rejection in pediatric heart transplant allografts.

BACKGROUND: The aim of this study was to assess the influence of IL-10 and TGFbeta1 gene polymorphisms on the development of acute rejection and coronary disease in pediatric heart transplant recipients. METHODS: Patients were classified as either Rejectors or Nonrejectors. Coronary artery disease (CAD) was diagnosed by angiography or on macroscopic examination. Genotyping PCR-SSP were performed for IL-10 and TGFbeta1 (codon 10 and 25) in 111 patients. Thirty-nine were Rejectors and 31 developed CAD. RESULTS: The proportion of IL-10 low-producers was higher in Rejectors than in Nonrejectors (respectively 46% versus 22%, P=0.009). IL-10 gene polymorphism was not associated with CAD. TGFbeta1-codon10-25 high-producers were 92.3% in Rejectors and 75% in Nonrejectors (P=0.026), 93.5% in patients with CAD and 76.2% in patients free from CAD (P=0.037). TGFbeta1-codon25 high-production separately analyzed correlated with CAD (31/31 high-producers in CAD=100% versus 69/80 in noCAD patients=86.2%, P=0.03). TGFbeta1-codon10 gene polymorphisms were not associated with CAD. CONCLUSION: IL-10 low-producers have an increased risk of acute rejection. High-expressors of TGFbeta1-codon10-25 have an increased risk of acute rejection and CAD, while TGFbeta1-codon25 high-production is associated with coronary disease. Genetic polymorphism may reveal patients at high-risk in whom therapies and monitoring should be adjusted.

Adolescent↗

PubMed2006

A randomized trial of inhaled cyclosporine in lung-transplant recipients.

BACKGROUND: Conventional regimens of immunosuppressive drugs often do not prevent chronic rejection after lung transplantation. Topical delivery of cyclosporine in addition to conventional systemic immunosuppression might help prevent acute and chronic rejection events. METHODS: We conducted a single-center, randomized, double-blind, placebo-controlled trial of inhaled cyclosporine initiated within six weeks after transplantation and given in addition to systemic immunosuppression. A total of 58 patients were randomly assigned to inhale either 300 mg of aerosol cyclosporine (28 patients) or aerosol placebo (30 patients) three days a week for the first two years after transplantation. The primary end point was the rate of histologic acute rejection. RESULTS: The rates of acute rejection of grade 2 or higher were similar in the cyclosporine and placebo groups: 0.44 episode (95 percent confidence interval, 0.31 to 0.62) vs. 0.46 episode (95 percent confidence interval, 0.33 to 0.64) per patient per year, respectively (P=0.87 by Poisson regression). Survival was improved with aerosolized cyclosporine, with 3 deaths among patients receiving cyclosporine and 14 deaths among patients receiving placebo (relative risk of death, 0.20; 95 percent confidence interval, 0.06 to 0.70; P=0.01). Chronic rejection-free survival also improved with cyclosporine, as determined by spirometric analysis (10 events in the cyclosporine group and 20 events in the placebo group; relative risk of chronic rejection, 0.38; 95 percent confidence interval, 0.18 to 0.82; P=0.01) and histologic analysis (6 vs. 19 events, respectively; relative risk, 0.27; 95 percent confidence interval, 0.11 to 0.67; P=0.005). The risks of nephrotoxic effects and opportunistic infection were similar for patients in the cyclosporine group and the placebo group. CONCLUSIONS: Inhaled cyclosporine did not improve the rate of acute rejection, but it did improve survival and extend periods of chronic rejection-free survival. (ClinicalTrials.gov number, NCT00268515.).

Acute Disease↗

PubMed2006

Acute antibody-mediated rejection of cardiac transplants.

Under the direction of the International Society for Heart and Lung Transplantation, a multidisciplinary review of the cardiac biopsy grading system was undertaken in 2004, with task forces examining the areas of histopathology of rejection, clinical issues, and research. An important new area addressed by the Immunopathology Task Force sub-committee was the clinical and diagnostic criteria for antibody-mediated rejection. This article is a companion paper to the revised working formulation for the standardization of nomenclature in the diagnosis of heart rejection and reviews the published literature documenting the serologic and morphologic evidence that antibody-mediated rejection is clinically significant and associated with graft loss, accelerated transplant-associated coronary artery disease, and death. This article also provides a more in-depth analysis of antibody-mediated rejection developed by the Immunopathology Task Force for revision of the 1990 working formulation for the standardization of nomenclature in the diagnosis of heart rejection.

Antibodies↗

PubMed2006

Anti-HLA alloantibodies in pediatric solid organ transplantation.

An increasing number of studies demonstrate the clinical impact of preformed and de novo anti-human leucocyte antigen alloantibody (HLA-Ab) in solid organ transplantation (Tx). The screening of HLA-Ab in candidates and transplant recipients has evolved over time, with continuous improvement in the sensitivity and specificity of assays for HLA-Ab detection. Furthermore, histologic markers of complement activation pathways are currently implemented in the diagnosis of antibody-mediated rejection (AMR). Therapeutic strategies, including depletion of HLA-Ab and B cells, have allowed Tx across antibody barriers, or have rescued patients with AMR. The purpose of the present review is to summarize the state-of-the-art of HLA-Ab detection, clinical significance and therapeutic strategies in pediatric solid organ Tx.

Child↗

PubMed2006

Allosensitized humans are at no greater risk of humoral rejection of GT-KO pig organs than other humans.

BACKGROUND: The availability of pigs homozygous for alpha1,3-galactosyltransferase gene-knockout (GT-KO) has enabled study of the incidence and cytotoxicity of primate antibodies directed to antigens other than Galalpha1,3Gal (Gal), termed non-Gal antigens. METHODS: Sera from 27 healthy humans and 31 patients awaiting renal allotransplantation, who were either unsensitized [panel reactive antibodies (PRA) < 10%] or allosensitized (PRA > 70%), were tested by flow cytometry for binding of immunoglobulin M (IgM) and IgG to peripheral blood mononuclear cells (PBMC) from both wild-type (WT) and GT-KO pigs. Complement-dependent cytotoxicity to WT and GT-KO PBMC was also measured. RESULTS: IgM and IgG from all 27 (100%) healthy human sera bound to WT PBMC, while 78% and 63% of these sera had IgM and IgG that bound to GT-KO PBMC, respectively. Mean binding to WT PBMC was significantly greater than GT-KO PBMC. Whereas 100% of sera were cytotoxic to WT PBMC, only 61% were cytotoxic to GT-KO PBMC, and the extent of lysis was significantly less. Neither mean binding of IgM and IgG nor cytotoxicity of unsensitized and allosensitized sera to WT and GT-KO PBMC was significantly different to that of healthy sera. CONCLUSIONS: More than half of the healthy humans tested had cytotoxic antibodies to GT-KO PBMC, but allosensitized patients will be at no greater risk of rejecting a pig xenograft by a humoral mechanism.

Animals↗

PubMed2006

Fatal transfusion-associated graft-versus-host disease in an immunocompetent recipient of a volunteer unit of red cells.

BACKGROUND: Transfusion-associated graft-versus-host disease (TAGVHD) is a lethal complication of transfusion of nonirradiated cellular blood components to a susceptible recipient. CASE REPORT: An 82-year-old man underwent cardiac surgery during which he received 6 units of red cells (RBCs) and a 6-unit pool of platelets (PLTs). He was discharged with a normal white blood cell (WBC) count and hemoglobin (Hb) level and a PLT count of 104x10(9) per L. He was readmitted 2 weeks later with a diffuse erythematous rash, a sore throat, and difficulty swallowing. His WBC count was 2.1x10(9) per L, his Hb level was 12.0 g per dL, and his PLT count was 131x10(9) per L. The next day he had worsening cytopenias: WBC count, 1x10(9) per L; Hb level, 10.9 g per dL; PLT count, 104x10(9) per L. He also had diarrhea. A marrow biopsy showed a severe hypoplasia without evidence of malignancy. A skin biopsy showed Grade II GVHD. The patient worsened and despite aggressive therapy he expired on Postoperative Day 42. DNA-based HLA testing of the 12 blood donors was performed. One of the RBC donors was found to be homozygous for an HLA Class I and Class II haplotype in the patient. CONCLUSION: This is the first reported case in the United States of fatal TAGVHD from RBCs in an immunocompetent patient who received a randomly selected unit of RBCs from a donor who was homozygous for a shared HLA haplotype. The policy of selective irradiation should be reexamined.

Aged↗

PubMed2005

Impact of ABCB1 (MDR1) haplotypes on tacrolimus dosing in adult lung transplant patients who are CYP3A5 3/3 non-expressors.

BACKGROUND: The influence of ABCB1 (MDR1) polymorphisms on tacrolimus dosing has been questioned in previous studies with contradictory findings, possibly due to the association between CYP3A5 polymorphisms and tacrolimus dosing. The objective of this study was to assess the effect of ABCB1 haplotypes from 3 distinct polymorphic sites on the tacrolimus level/dose [L/D] in lung transplant patients limited to CYP3A5 *3/*3 non-expressors. METHOD: A total of 91 lung transplant patients treated primarily with tacrolimus and prednisone were enrolled, and clinical information on drug dosing and blood levels was collected. The [L/D] was calculated for patients receiving tacrolimus at 1, 3, 6, 9 and 12 months post transplant. ABCB1 polymorphisms at C1236T, G2677T, and C3435T were assessed by PCR amplification and DNA sequencing. Haplotypes were estimated by Arlequin ver.2.00. Haplotype effects on tacrolimus [L/D] were assessed by two-way ANOVA. RESULTS: Of the 10 haplotypes, CGC, TTT and CGT accounted for 44.1%, 40.7% and 7.6% of the total haplotypes, respectively. The tacrolimus [L/D] value in the CGC-CGC patients was significantly lower than in patients with CGC-TTT and TTT-TTT genotypes at the first month (mean [L/D]=1.45 versus 3.10 and 3.97 ngxmL(-)(1) /mg/day), and throughout the first post transplant year. CONCLUSION: This study demonstrates that ABCB1 haplotypes derived from three common polymorphisms are associated with tacrolimus dosing in lung transplant patients when eliminating the confounder CYP3A5 genotype.

ATP Binding Cassette Transporter, Subfamily B↗

PubMed2005

Revision of the 1990 working formulation for the standardization of nomenclature in the diagnosis of heart rejection.

In 1990, an international grading system for cardiac allograft biopsies was adopted by the International Society for Heart Transplantation. This system has served the heart transplant community well, facilitating communication between transplant centers, especially with regard to patient management and research. In 2004, under the direction of the International Society for Heart and Lung Transplantation (ISHLT), a multidisciplinary review of the cardiac biopsy grading system was undertaken to address challenges and inconsistencies in its use and to address recent advances in the knowledge of antibody-mediated rejection. This article summarizes the revised consensus classification for cardiac allograft rejection. In brief, the revised (R) categories of cellular rejection are as follows: Grade 0 R--no rejection (no change from 1990); Grade 1 R--mild rejection (1990 Grades 1A, 1B and 2); Grade 2 R--moderate rejection (1990 Grade 3A); and Grade 3 R--severe rejection (1990 Grades 3B and 4). Because the histologic sub-types of Quilty A and Quilty B have never been shown to have clinical significance, the "A" and "B" designations have been eliminated. Recommendations are also made for the histologic recognition and immunohistologic investigation of acute antibody-mediated rejection (AMR) with the expectation that greater standardization of the assessment of this controversial entity will clarify its clinical significance. Technical considerations in biopsy processing are also addressed. This consensus revision of the Working Formulation was approved by the ISHLT Board of Directors in December 2004.

Biopsy↗

PubMed2005

EBV-specific memory CD8+ T cell phenotype and function in stable solid organ transplant patients.

Immune responses to EBV in immunosuppressed (IS) solid organ transplant (SOTx) recipients have not been well characterized. Here we evaluate the phenotype and function of EBV-specific CD8+ T cells in peripheral blood isolated from "stable" IS SOTx recipients. The EBV-specific CD8+ T cell memory subset distribution in the peripheral blood of patients was examined by flow cytometric analysis using HLA-A2 tetramers incorporating BMLF1 (lytic), and LMP2 and EBNA3A (latent)-derived peptides, in conjunction with mAbs against the CD45RO, CD45RA, and CD62L markers. The ability of CD8+ T cells to produce IFN-gamma in response to the same EBV-derived peptides was measured by ELISPOT assay. Patients and healthy normal donors exhibited similar anti-EBV CD8+ T cell frequencies and specificities against the EBV epitopes evaluated. When compared to healthy normal donors, an overall significant expansion of the CD8+ T cell "effector memory" (CD45RO+/CD62L-) pool, including that of EBV "latent" (LMP2 and EBNA3A)-specific CD8+ T cells was detected in IS SOTx patients. However, the patients' EBV-specific CD8+ T cells showed decreased IFN-gamma production to the EBV-peptide stimulation. These results indicate that the impairment of EBV-specific CD8+ T cell activity is not due to clonal depletion, but is mainly due to impaired functional activation.

Antigens, Viral↗

PubMed2005

Augmentation of type-1 polarizing ability of monocyte-derived dendritic cells from chronically immunosuppressed organ-transplant recipients.

BACKGROUND: Chronic immunosuppressive (IS) therapy impairs normal T-cell immune surveillance and may predispose to opportunistic infections and malignancies that represent life-threatening complication of solid-organ transplantation (SOTx). Our study was designed to ascertain the impact of chronic in vivo administration of IS on the ability of monocyte-derived dendritic cells (MoDC) to differentiate, mature, and function ex vivo. The potential of these cells to be implemented for DC-based adoptive immunotherapy was also considered. METHODS: MoDCs were propagated by conventional procedures, their phenotype was analyzed by flow cytometry, and their function was assessed by mixed leukocyte reaction, enzyme-linked immunoadsorbent assay, and ELISPOT assays. Nuclear translocation of nuclear factor (NF)-kB was analyzed by electrophoretic mobility shift assay. RESULTS: Circulating DC1s in peripheral blood were reduced in SOTx patients. MoDCs generated from patients displayed higher endocytic activity versus normal DCs, indicating their comparative immaturity. Patients' DCs exposed to pro-inflammatory cytokines (tumor necrosis factor-alpha, interleukin [IL]-1beta, and IL-6) were less able to mature, to stimulate recall antigen (Ag)- or allo-Ag-induced proliferation responses, or to secrete IL-12p70. These deficiencies were associated with a decrease in NF-kB translocation. In contrast, combination of pro-inflammatory cytokines and interferon (IFN)-gamma (a Th1-polarizing factor) augmented patients' DC1-type function and IL-12p70 production by way of an NF-kB-independent mechanism. CONCLUSIONS: Chronic IS restrains DC differentiation, maturation, and function at a transcriptional level; however, type-1 polarizing potential of patients' DC1 can be augmented ex vivo by a two-signal stimulation provided by pro-inflammatory cytokines and IFN-gamma. These results may have implications for DC-based immunotherapy of malignancies in the transplantation setting.

Active Transport, Cell Nucleus↗