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At least 469 records · Page 26Linked to original sources
PubMed1995

FK 506 rescue therapy for hepatic allograft rejection: experience with an aggressive approach.

Although initial experiences with FK 506 rescue therapy for acute hepatic allograft rejection have provided promising results, analysis of available data indicates that inferior results are obtained when FK 506 rescue therapy is initiated in the latter stages of rejection. Since its initial availability, we have applied an aggressive approach towards FK 506 rescue therapy based on early conversion and assiduous dosing. We have reviewed our experience with this approach in patients with refractory hepatic allograft rejection to provide an assessment of this approach. Sixteen patients were treated for corticosteroid and OKT3-resistant acute hepatic allograft rejection. Fourteen patients were treated for cellular rejection and 2 for humorally-mediated rejection. Median follow-up was 7.3 months posttransplant and 6.0 months post-initiation of FK 506 therapy. Median time to first rejection was 8 days and median time to FK 506 therapy was 29 days. Laboratory values at the time of initiation of FK 506 therapy included: mean serum bilirubin, 4.0 +/- 3.1 mg/dl and SGPT 136 +/- 105 U/l. Prior to FK 506 therapy, patients received an average of 35.5 +/- 19.1 mg/kg of bolus/taper corticosteroids (prednisone equivalent) and 11.25 +/- 4.8 days of OKT3 therapy. FK 506 therapy was successful in reversing all episodes of rejection. Median time to rejection reversal with FK 506 rescue therapy was 23 days (mean +/- SD, 27.6 +/- 16.7 days) in patients with cellular rejection. Time to rejection reversal was 26 and 28 days in the 2 patients with humoral rejection. Patient and graft survival at 6 months were 100%/100%, and 94%/94% at 12 months.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

The antirheumatic drug disodium aurothiomalate inhibits CD4+ T cell recognition of peptides containing two or more cysteine residues.

The mechanism of action of antirheumatic gold drugs, such as disodium aurothiomalate (Au(I)TM), has not been clearly identified. Gold drugs inhibit T cell activation induced by mitogen and anti-CD3 mAb in vitro at relatively high concentrations. However, since gold drugs fail to induce immunosuppression in vivo, the pharmacologic relevance of this finding is doubtful. In this study, we asked whether Au(I)TM interferes with processing and presentation of defined Ags to T cells. Using a panel of murine CD4+ T cell hybridomas, we found that low concentrations of Au(I)TM (< or = 10 microM) led to a markedly reduced IL-2 release of T cell hybridoma clones that recognized peptides containing two or more cysteine (Cys) residues, such as bovine insulin A1-14. Since disodium thiomalate alone had no effect, the inhibition was due to Au(I). IL-2 production induced by anti-CD3 mAb stimulation was not affected by the low concentration of Au(I)TM used. Au(I)TM had no effect on the presentation of peptides containing no or only one Cys residue(s). In contrast to the unmodified insulin peptide A1-14, Au(I) could not inhibit recognition of an insulin peptide in which Cys residues in positions 6 and 11 were replaced by serine. Most likely, the observed inhibition is mediated by formation of chelate complexes between Au(I) and two Cys thiol groups of the affected antigenic peptides. The peptide-specific inhibitory effect of Au(I) on Ag presentation described here might contribute to the therapeutic effect of Au(I) compounds in rheumatoid arthritis.

Amino Acid Sequence↗
PubMed1995

De novo membranous glomerulopathy in renal allografts with unusual histology.

We describe two cases of de novo membranous glomerulopathy in the renal allograft, with unusual histologic findings. In one patient the allograft nephrectomy specimen showed numerous foam cells in the intima of hyperplastic arteries along with prominent features of chronic rejection. In the other patient, prominent IgM deposits were seen in the glomerular mesangium without chronic rejection.

Adult↗
PubMed1995

Effect of calcium-channel blocker on tumour necrosis factor alpha (TNF alpha) production in cyclosporin-treated renal transplant recipients.

PURPOSE OF THE STUDY: The influence of calcium-channel blocker treatment on in-vitro TNF alpha production by peripheral blood mononuclear cells (PBMC) from renal transplant recipients treated with cyclosporin was studied. DESIGN: We compared spontaneous and OKT3-induced TNF alpha production of 12 renal transplant recipients treated with calcium-channel blocker therapy with that of 18 renal transplant recipients who were never treated with a calcium antagonist. RESULTS: The two groups were similar with regards to age, time after transplantation, dosage of immunosuppressive drugs, and blood cyclosporin levels. Spontaneous (481 +/- 161 versus 319 +/- 74 pg/ml, n.s.) and OKT3-induced (745 +/- 182 versus 632 +/- 112 pg/ml, n.s.) TNF alpha production were similar in both groups. CONCLUSIONS: The results indicate that in cyclosporin-treated renal transplant recipients calcium-channel blockers do not affect TNF alpha production.

Adult↗
PubMedDate not supplied

Combined antiviral and immunoglobulin therapy as prophylaxis against cytomegalovirus infection after heart transplantation.

BACKGROUND: Cytomegalovirus is a frequent cause of infection and morbidity after heart transplantation, especially in patients treated with antilymphocytic drugs where the incidence may be as high as 50%. METHODS: To determine the efficacy of combined antiviral and intravenous immune globulin therapy for prevention of cytomegalovirus disease in transplant recipients receiving OKT3 and to compare two different antiviral drug regimens, we reviewed 115 transplant recipients from December 1988 to December 1993 who survived for more than 30 days. Of these, 29 received oral acyclovir for 3 months (group A) and 86 received intravenous ganciclovir for 2 weeks followed by oral acyclovir up to 3 months (group G); all received six infusions of 5% intravenous immune globulin over 2 months. All patients had OKT3 for 10 to 14 days and triple-drug immunosuppression. RESULTS: Cytomegalovirus disease (pneumonitis, gastroenteritis, or leukopenia with fever) occurred in 10% of patients (12 of 115 patients) and was confirmed by positive culture, typical microscopic inclusions, or polymerase chain reaction. In 91 seropositive recipients, there was a trend to less cytomegalovirus disease in group G (3.0%, 2 of 67 patients) than in group A (12.5%, 3 of 24 patients) (p = 0.11), which was more apparent in recipients with seropositive donors where the incidence was reduced from 16.7% (group A) to 2.4% (group G; p = 0.08). In 24 seronegative recipients, cytomegalovirus disease incidence was higher overall and not significantly less in group G (26%, 5 of 19 patients) than in group A (40%, two of five patients) (p = Not significant). CONCLUSIONS: Prophylaxis with combined antiviral and immune globulin therapy produces a low (10%) incidence of cytomegalovirus disease in OKT3-treated heart transplant recipients. In seropositive recipients treated with combined therapy, ganciclovir may be more effective than acyclovir. Larger trials and more aggressive prophylactic strategies are needed in seronegative patients who receive hearts from seropositive donors.

Acyclovir↗
PubMed1995

Critical role of CD28/B7 costimulation in the development of human Th2 cytokine-producing cells.

CD28 is a major costimulatory signal receptor for T cells. We have used human naive CD4+ cells from cord blood to analyze the effect of the CD28/B7 costimulatory pathway on development of T helper (Th) subsets. We show that CD28 costimulation is critical for development of the Th2 cytokine-producing cells and that in the absence of CD28 costimulation, cells are not primed to produce Th2 cytokines and consequently "default" to the Th1 subset, independent of the presence of exogenous cytokines. After CD28 costimulation, cells differentiate into a subset that produces Th2 cytokines. However, further CD28 costimulation is not required to maintain Th2 cytokine production. We conclude that D28 costimulation is critical for the development of Th0 and Th2 subsets, but not for the maintenance of cytokine production.

Animals↗
PubMed1995

Two pathways of exocytosis of cytoplasmic granule contents and target cell killing by cytokine-induced CD3+ CD56+ killer cells.

Cytokine-induced killer (CIK) cells are non-major histocompatibility complex-restricted cytotoxic cells generated by incubation of peripheral blood lymphocytes with anti-CD3 monoclonal antibody (MoAb), interleukin-2 (IL-2), IL-1, and interferon-gamma. Cells with the greatest effector function in CIK cultures coexpress CD3 and CD56 surface molecules. CIK cell cytotoxicity can be blocked by MoAbs directed against the cell surface protein leukocyte function associated antigen-1 but not by anti-CD3 MoAbs. CIK cells undergo release of cytoplasmic cytotoxic granule contents to the extracellular space upon stimulation with anti-CD3 MoAbs or susceptible target cells. Maximal granule release was observed from the CD3+ CD56+ subset of effector cells. The cytoplasmic granule contents are lytic to target cells. Treatment of the effector cells with a cell-permeable analog of cyclic adenosine monophosphate (cAMP) inhibited anti-CD3 MoAb and target cell-induced degranulation and cytotoxicity of CIK cells. The immunosuppressive drugs cyclosporin (CsA) and FK506 inhibited anti-CD3-mediated degranulation, but did not affect cytotoxicity of CIK cells against tumor target cells. In addition, degranulation induced by target cells was unaffected by CsA and FK506. Our results indicate that two mechanisms of cytoplasmic granule release are operative in the CD3+ CD56+ killer cells; however, cytotoxicity proceeds through a cAMP-sensitive, CsA- and FK506-insensitive pathway triggered by yet-to-be-identified target cell surface molecules.

Biomarkers↗
PubMed1995

Induction therapy with cyclosporine without cytolytic agents results in a low incidence of acute rejection without significant renal impairment in heart transplant patients.

Since 1989, the immunosuppressive regimen used in all heart transplant patients at our center has consisted of (i) cyclosporine induction therapy (pretransplant p.o. 2-6 mg/kg depending on serum creatinine level, with immediate post-transplant i.v. therapy at 1-3 mg/h until p.o. therapy alone maintains a whole blood trough level of 300 ng/ml by RIA); (ii) azathioprine (2.5 mg/kg/d i.v./p.o.); (iii) methylprednisolone i.v. for 24 h and then prednisone p.o. at 1 mg/kg/d, tapering to 0.1 mg/kg/d at 1 yr. No prophylactic cytolytic agents (ALG, OKT3) were given. One hundred consecutive patients have been followed for periods of 4-56 months (mean 27 months). The incidence of acute rejection requiring increased therapy was 24%, with only 7% requiring i.v. steroids, 2 of whom (2%) also required ALG and/or OKT3, and with 17% requiring increased oral immunosuppression alone. Mean creatinine levels (mg/dl) were 1.3 pretransplant, 1.4 on d 7, 1.5 at 30 d, and 1.8 after 2 yr. Only 1 patient required temporary hemodialysis. Survival was 98% at 30 d, 94% at 1 yr, and 92% at 2 yr. We conclude that cyclosporine induction therapy with steroids and azathioprine without any cytolytic agent results in a low incidence of acute rejection without jeopardizing renal function.

Acute Disease↗
PubMed1995

Treatment of steroid-resistant graft-versus-host disease after allogeneic bone marrow transplantation with anti-CD3/TCR monoclonal antibodies.

Acute graft-versus host disease (GVHD), one of the major complications of allogeneic bone marrow transplantation (BMT), occurs in 30-50% of all patients transplanted from HLA-identical sibling donors and in 50-80% of all patients transplanted from an unrelated or HLA-mismatched family donor, despite GVHD prophylaxis with methotrexate and cyclosporin. We report our experience with OKT3/BMA031 treatment in 14 patients with severe steroid-resistant GVHD following allogeneic BMT. Three of 5 patients treated in the early post-transplant period with OKT3 remitted and 2 of 3 became long-term survivors. Two patients treated for extensive chronic GVHD showed only minor responses. Five of 7 patients treated with BMA031 showed a partial remission; no complete remission was seen after treatment with this antibody. Shortly after the introduction of OKT3 or BMA031 therapy a rapid decline of the lymphocyte count, especially the CD3+ subset, was observed coinciding with a relative increase of CD56+ lymphocytes and of gamma/delta TCR+ T cells. Increasing numbers of CD3+ lymphocytes preceded recurrence of acute GVHD in three patients. In contrast, persisting CD3-lymphocytopenia was associated with complete clearance of acute GVHD. The incidence of infectious complications following OKT3 or BMA031 therapy was high (42%). Thus, to improve treatment results of severe acute GVHD, prophylactic or pre-emptive strategies are required to reduce the rate of fatal viral and fungal infections.

Acute Disease↗
PubMed1994

Sparing of first dose effect of monovalent anti-CD3 antibody used in allograft rejection is associated with diminished release of pro-inflammatory cytokines.

The murine monoclonal antibody OKT3 is the best known of the anti-CD3 antibodies used for the prevention and treatment of renal allograft rejection. Use of this antibody is associated with improved graft outcome but it has a number of adverse effects thought to result from the massive release of pro-inflammatory cytokines. It has been postulated that OKT3 causes cytokine release because of cross-linking of CD3 molecules on the cell surface by bivalent anti-CD3 antibodies, such as OKT3, and the simultaneous binding of the Fc regions of these monoclonal antibodies to Fc receptors on other cells resulting in cell activation. Monovalent antibodies directed against the CD3 antigen should not, in theory, cause cell activation and cytokine release by this postulated mechanism. This study details the use of a monovalent anti-CD3 monoclonal antibody in the treatment of allograft rejection in five renal transplant recipients and documents the degree of TNF, IFN-g and IL6 release generated after antibody injection. Monovalent anti-CD3 monoclonal antibody reversed the rejection episode for which it was used and was well tolerated in all patients. TNF, IFN-g and IL6 measurement showed that little pro-inflammatory cytokine release occurred after this drug. It is likely that the relative lack of side-effects of monovalent anti-CD3 reflects the blunted release of pro-inflammatory cytokines. Monovalent anti-CD3 monoclonal antibody may be a useful addition to the reagents available to treat allograft rejection.

Acute Disease↗
PubMed1995

The outer surface lipoprotein A of Borrelia burgdorferi provides direct and indirect augmenting/co-stimulatory signals for the activation of CD4+ and CD8+ T cells.

Naive CD4+ and CD8+ T cells require two distinct signals to proliferate and to express effector functions [1]. One is provided by the antigen receptor on the T cell (TCR) after its encounter with antigenic peptides associated with class I or II major histocompatibility complex (MHC) molecules on antigen-presenting cells (APC) [2]. The second signal, which is not antigen-specific but essential for proliferation and differentiation of naive T cells, is provided by co-stimulatory structures. The major co-stimulatory molecules for CD4+ T cells seem to be B7 [3], B7.2 [4,5], and heat-stable antigen (HSA) [6]. These molecules are expressed on a variety of naive and/or activated APC and bind to CD28 and CTLA-4 and possibly other, as yet undefined, TCRs [3,7]. Optimal T cell activation only occurs when co-stimulatory molecules and ligands for the TCR are expressed on the same APC [8,9]. However, co-stimulation for T cells may also be provided via bystander cells [8,9] or by glycoproteins of the extracellular matrix, like fibronectin [10] and laminin [11]. In this case, T-cell VLA integrins function as signaling molecules [10,11]. This indicates that antigen-specific T-cell activation may also occur in areas where antigens are presented in association with extracellular matrix proteins. The recent finding that the invasion protein of Yersinia spp. delivers co-stimulatory signals to anti-CD3-activated human T cells, most probably through the b1 integrins, suggests that bacterial products can also bind to contribute to the activation of T cells [12].(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

The incidence of antibody formation to OKT3 consequent to its use in organ transplantation.

Enzyme-linked immunosorbent assays were performed on 12,133 serum samples to determine the incidence of anti-OKT3 antibody formation among transplant recipients who had received OKT3 for rejection treatment or prophylaxis. High anti-OKT3 antibody titers (> or = 1:1000) were detected in 5.8% of samples drawn 2 to 8 weeks following initiation of OKT3 therapy. The frequency of high titers differed by organ (6.9%, 2.7%, and 5.3% for kidney, heart, and liver, respectively; P < 0.001) and by sampling times (P < 0.001). The highest frequency of positive titers was obtained in samples obtained between 2 and 4 weeks following the initiation of OKT3. For all transplant recipients and for kidney recipients alone, multivariate logistic regression showed that the risk of high anti-OKT3 titers varied significantly at 2 to 4 weeks and at 4 to 6 weeks (but not at 6 to 8 weeks) with age (the youngest patients had the highest incidence, with a steady decline after age 30; P < 0.05), course of therapy (lowest frequencies followed a first course of OKT3; P < 0.001), and transplant number (lowest frequencies followed a first transplant; P < 0.01). Analyses of a set of patients on whom immunosuppressive regimen information was available indicated that prophylactic or maintenance treatment with CsA was associated with a significantly lower frequency of high-titer anti-OKT3 antibodies than was therapy without CsA (P < 0.001). In conclusion, this series provides confirming evidence that high-titer anti-OKT3 antibodies, which are of concern whenever retreatment with OKT3 is contemplated, occur in a low percentage of patients and are associated with such factors as age, previous transplantation or courses of therapy with OKT3, and treatment with CsA.

Adolescent↗
PubMed1994

Cytokines and transplantation: a clinical perspective.

Cytokines are endogenous small peptides that regulate cell growth and proliferation. In allogeneic transplantation, they function as critical immunologic mediators. Allograft rejection is dependent on interactions between antigen-presenting cells, T lymphocytes, accessory molecules, and proinflammatory cytokines (interleukins-1, -2, and -6; interferon-gamma; and tumor necrosis factors). Alternatively, other cytokines (interleukins-4, -5, and -10; transforming growth factor-beta) may suppress allograft rejection. Observation and manipulation of cytokine responses are an essential component of the immunopharmacology and clinical management of transplant recipients. Specific areas of interest include immunologic monitoring, pharmacologic immunosuppression, monoclonal antibody development, induction of tolerance, and the OKT3-related cytokine release syndrome. This review explores the impact of advances in cytokine physiology and biotechnology on clinical transplantation.

Animals↗
PubMed1995

Treatment with okadaic acid reveals strong threonine phosphorylation of CD18 after activation of CD11/CD18 leukocyte integrins with phorbol esters or CD3 antibodies.

The CD11/CD18 leukocyte integrins comprise three heterodimers involved in leukocyte adhesion. CD11/CD18 avidity may be regulated intracellularly, and the CD18 polypeptide has previously been shown to become phosphorylated in leukocytes after phorbol ester stimulation. The importance of phosphorylation in the regulation of CD11/CD18 avidity has, however, remained unclear. We have now activated T cells using phorbol esters, CD3, and CD44 Abs. Both phorbol ester and CD3 treatment activated protein kinase C. CD18 was shown to become more stably phosphorylated after phorbol ester treatment and more transiently so after CD3 stimulation. The phosphorylation was strongly augmented by okadaic acid, a serine/threonine phosphatase inhibitor. While phorbol ester treatment caused phosphorylation mainly on serine, in okadaic acid-pretreated cells, both phorbol ester treatment as well as CD3 stimulation revealed strong threonine phosphorylation. Since earlier mutational studies have demonstrated the functional importance of cytoplasmic threonine residues in CD18, the threonine phosphorylation reported here indicates the role of threonine phosphorylation in the regulation of CD11/CD18 avidity.

Alkaloids↗
PubMed1995

Anti-CD3 x anti-tumor F(ab')2 bifunctional antibody activates and retargets tumor-infiltrating lymphocytes.

Bifunctional Abs (BFA) with specificity for the TCR/CD3 complex of T cells and tumor Ag can bridge T lymphocytes and tumor cells and, thereby, trigger activation events. The ability of intact and F(ab')2 anti-CD3 (500A2) x anti-p97 (96.5) BFA to induce activation of T lymphocytes in the presence of murine melanoma tumor cells (CL-62) expressing human melanoma-associated Ag (p97) was investigated in vitro and in vivo. Intact and F(ab')2 BFA induced significant proliferation of T lymphocytes in the presence of p97+ tumor cells. Incubation of splenocytes with intact or F(ab')2 BFA and p97+ tumor cells increased BFA-mediated cytotoxicity against relevant tumor cells. Intact BFA, in contrast to F(ab')2 BFA, induced some activation of T cells in vitro even in the absence of p97+ target cells. In nontumor-bearing mice, administration of F(ab')2 BFA, in contrast to intact BFA, did not increase cytotoxic activity of lymph node (LN) cells and splenocytes. However, when F(ab')2 BFA was administrated into CL-62-bearing mice, an increase of BFA-mediated cytotoxicity of tumor-infiltrating lymphocytes, but not splenocytes nor LN cells, was observed. Moreover, in D-galactosamine-sensitized mice, injection of intact BFA (1 microgram/mice) induced 100% lethality, whereas the same dose of F(ab')2 BFA was not toxic. These results demonstrate that F(ab')2 BFA can induce activation of cytotoxic lymphocytes only in the presence of relevant tumor cells, both in vitro and in vivo. That these activated lymphocytes can be redirected to lyse relevant tumor cells by the same BFA has important implications for the clinical application of BFA anti-tumor therapies.

Animals↗
PubMed1995

T cells infiltrating non-Hodgkin's B cell lymphomas show altered tyrosine phosphorylation pattern even though T cell receptor/CD3-associated kinases are present.

Although tumor infiltrating lymphocytes (T-TIL) from B cell non-Hodgkins lymphoma patients contain tumor-reactive T cells, they display poor proliferation and IFN-gamma production when stimulated through the TCR-CD3. To determine if there was altered signaling linked to TCR-CD3 ligation, tyrosine phosphorylation was examined in T-TIL because it represents an early and critical event in T cell activation. After stimulation with anti-CD3 Ab, Western blotting with anti-phosphotyrosine showed reduced phosphorylation in T-TIL when compared with peripheral blood-derived T cells from normal individuals. The altered phosphorylation was not due to the reduced expression of signaling elements linked to the TCR-CD3 complex. T-TIL expressed normal levels of CD3 epsilon, TCR zeta chain, and the three tyrosine kinases, p56lck (Lck), p59fyn, and ZAP-70. However, in T-TIL, anti-Lck Ab reacted with a 60-kDa protein, which appears to be the phosphorylated form of Lck. Binding of anti-Lck Ab to the 60-kDa protein was blocked by Lck peptide. In addition, anti-Lck Ab immunoprecipitated a phosphorylated 60-kDa protein from gamma-32P-labeled T-TIL that was not seen in normal resting T cells. In vitro kinase assay studies also demonstrated that TCR-CD3 engagement increased the kinase activity of Lck in normal T cells but not in T-TIL. These results suggest that although T-TIL from B cell non-Hodgkins lymphoma patients contain the signal transduction molecules associated with TCR-CD3 activation pathway, they are impaired in tyrosine phosphorylation and Lck activity, which may contribute to the functional defects of these cells.

Humans↗