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T B Strom

Publications and source records attributed to T B Strom.

At least 73 records · Page 4Linked to original sources
PubMed1997

Type 2 helper T cell-type cytokines and the development of "infectious" tolerance in rat cardiac allograft recipients.

CD4-targeted therapy with a nondepleting RIB-5/2 mAb abrogates accelerated (< 36 h) rejection in presensitized LEW rats and results in permanent acceptance of LBNF1 cardiac allografts in conjunction with the features of infectious tolerance. This study examined the role and functional significance of the Th1 and Th2 cytokine network and systemic host allospecific Ab (allo-Ab) responses in the development of the infectious tolerance pathway in this model. Long term survival of cardiac transplants in rats treated with the tolerizing RIB-5/2 mAb regimen was accompanied by profound depression of Th1 (IL-2 and IFN-gamma) and Th2 (IL-4, IL-10) cytokines at the graft site, as shown by competitive template reverse transcription-PCR and immunohistochemistry. In contrast, the expression of Th2-type cytokines was selectively up-regulated after transfer of infectious tolerance by spleen cells into new generations of primary and secondary test recipients. Donor-specific circulating IgM allo-Ab responses were diminished throughout, and the switch from IgM to IgG allo-Ab was completely prevented in tolerant hosts, as shown by flow cytometry. The demonstration that treatment with cytolytic anti-CD4, but not anti-CD8, mAb recreated rejection of test cardiac allografts with simultaneous down-regulation of IL-4 mRNA/protein expression underlines the importance of this cytokine in the development of infectious tolerance. Hence, this report documents distinct cytokine elaboration patterns in animals tolerized by CD4-targeted therapy compared with those rendered tolerant by putative regulatory Th2-like cells. The mechanism of tolerance in anti-CD4 mAb-treated hosts appears distinct from that operating in the absence of mAb, when the tolerant state is being transferred in an infectious manner to new cohorts of test recipients.

Adoptive Transfer↗
PubMed1997

Quantitative detection of immune activation transcripts as a diagnostic tool in kidney transplantation.

Procedures to diagnose renal allograft rejection depend upon detection of graft dysfunction and the presence of a mononuclear leukocytic infiltrate; however, the presence of a modest cellular infiltrate is often not conclusive and can be detected in non-rejecting grafts. We have pursued a molecular approach utilizing reverse transcription (RT)-PCR to test the diagnostic accuracy of multiple immune activation gene analysis as means to diagnose renal allograft rejection. The magnitude of intragraft gene expression of 15 immune activation genes was quantified by competitive RT-PCR in 60 renal allograft core biopsies obtained for surveillance or to diagnose the etiology of graft dysfunction. Results were compared with a clinicopathological analysis based upon the histological diagnosis (Banff criteria) and the response to antirejection treatment. During acute renal allograft rejection intragraft expression of the interleukin (IL)-7 (P < 0.001), IL-10 (P < 0.0001), IL-15 (P < 0.0001), Fas ligand (P < 0.0001), perforin (P < 0.0001), and granzyme B (P < 0.0015), but not IL-2, interferon gamma, or IL-4, genes is significantly heightened. Amplified RANTES and IL-8 gene transcripts are sensitive but nonspecific markers of rejection. A simultaneous RT-PCR evaluation of perforin, granzyme B, and Fas ligand identifies acute rejection, including cases with mild infiltration, with extraordinary sensitivity (100%) and specificity (100%). Effective antirejection therapy results in a rapid down-regulation of gene expression. The combined analysis of Fas ligand, perforin, and granzyme B gene expression by quantitative RT-PCR provides a reliable tool for diagnosis and follow-up of acute renal allograft rejection. Its accuracy and a potential rapid application within few hours suggest its use in the clinical management of renal transplant patients.

Adult↗
PubMed1997

Immunoregulatory drugs: mechanistic basis for use in organ transplantation.

Multiple immunoregulatory drugs, capable of constraining cell activation, differentiation, and/or proliferation, and each with distinct side effects, are currently used in the clinic to facilitate organ engraftment. Cyclosporine, azathioprine, corticosteroids, FK506 (tacrolimus), and RS61443 (mycophenolate mofetil) have already been approved by the United States Food and Drug Administration. Rapamycin (sirolimus), mizoribine, and 15-deoxyspergualin are being explored for their clinical efficacy. Based on their subcellular site of action, the immunosuppressants can be considered as: inhibitors of transcription (cyclosporine, tacrolimus), inhibitors of nucleotide synthesis (azathioprine, mycophenolate mofetil, mizoribine), inhibitors of growth factor signal transduction (sirolimus), and inhibitors of differentiation (15-deoxyspergualin). Clearly, the transplant clinician now has a greater choice in the selection and application of immunosuppressants in the clinic for the fine regulation of anti-allograft immunity. The existing hypothesis regarding the mechanisms of action of immunosuppressants is that they all function to prevent allograft rejection by preventing/inhibiting cell activation, cytokine production, differentiation, and/or proliferation. A complementary supposition is that some of the immunosuppressants might regulate the anti-allograft repertory by stimulating the expression of immunosuppressive molecules and/or cells.

Animals↗
PubMed1997

Induction of peripheral T cell tolerance in vivo requires CTLA-4 engagement.

Studies of T cell anergy in vitro have led to the widely accepted view that anergy is induced by T cell antigen recognition without costimulation. We show that the induction of T cell anergy in vivo is due to an abortive T cell response that requires recognition of B7 molecules, since blocking B7 maintains T cells in an unactivated but functionally competent state. Furthermore, the induction of anergy is prevented by blocking CTLA-4, the inhibitory T cell receptor for B7 molecules. Thus, in vivo T cell anergy may be induced not because of a lack of costimulation, but as a result of specific recognition of B7 molecules by CTLA-4. In contrast, blocking CD28 on T cells prevents priming but not the induction of tolerance. Therefore, the outcome of antigen recognition by T cells is determined by the interaction of CD28 or CTLA-4 on the T cells with B7 molecules.

Abatacept↗
PubMed1997

B7-1 and B7-2 have overlapping, critical roles in immunoglobulin class switching and germinal center formation.

Humoral immune responses were characterized in mouse strains lacking either or both B7 molecules. Mice deficient in both B7-1 and B7-2 failed to generate antigen-specific IgG1 and IgG2a responses and lacked germinal centers when immunized by a number of routes and even in the presence of complete Freund's adjuvant. These results demonstrate that B7-mediated signaling plays a critical role in germinal center formation and immunoglobulin class switching in vivo. Mice lacking only B7-1 or B7-2 mounted high-titer antigen-specific IgG responses when immunized in complete Freund's adjuvant, indicating that B7-1 and B7-2 can have overlapping, compensatory functions for IgG responses. When immunized intravenously without adjuvant, B7-2-deficient mice failed to switch antibody isotypes or form germinal centers, whereas B7-1-deficient mice gave antibody responses comparable with wild-type mice. Thus, B7-2 has an important role in initiating antibody responses in the absence of adjuvant, but the induction of B7-1 by adjuvant in B7-2-deficient mice can compensate for the absence of B7-2.

Abatacept↗
PubMed1997

Interleukin-2 fusion protein (DAB389IL-2) selectively targets activated human peripheral blood and lamina propria lymphocytes.

Activated mucosal T lymphocytes correlate with the intestinal inflammation of inflammatory bowel disease. Activated T cells elaborate interferon-gamma (IFN-gamma) and express high-affinity interleukin-2 (IL-2) receptors. The IL-2/diphtheria toxin fusion protein (DAB389IL-2) has been shown to specifically kill high affinity IL-2 receptor-bearing cells. We tested whether DAB389IL-2 could specifically target activated lamina propria lymphocytes. Lymphocytes were activated in vitro with phytohemagglutinin and IL-2 for 24-48 hr. Toxin efficacy was determined by the [14C]leucine incorporation, IFN-gamma ELISA, and flow cytometry. DAB389IL-2 (10(-11) M) inhibited protein synthesis by 80% in activated lamina propria lymphocytes. This inhibition was blocked by coculture of either excess IL-2 or a nonfunctional IL-2 diphtheria toxin mutant protein. DAB389IL-2 (10(-12) M) also significantly reduced the numbers of activated helper T cells and IFN-gamma levels in 24-hr cultures. DAB389IL-2 specifically targets activated IL-2 receptor-positive lamina propria lymphocytes and is a potential new therapeutic agent for patients with active inflammatory bowel disease.

Diphtheria Toxin↗
PubMed1997

Adenovirus-mediated beta-galactosidase gene delivery to the liver leads to protein deposition in kidney glomeruli.

The many cell types of the kidney, precisely arranged, allow this organ to perform its complex physiologic functions. However, this architectural complexity makes gene transfer into the kidney difficult. One approach to delivering a therapeutic protein to the kidney is to transfer a gene to a non-renal tissue. Release of the protein into the circulation might then result in deposition in the kidney, if the protein has the appropriate molecular properties. In this study, we found that parenterally administered replication deficient adenovirus carrying the beta-galactosidase gene resulted in intense beta-galactosidase gene expression in hepatocytes. As a result of immune attack on transduced hepatocytes, beta-galactosidase protein from these cells is released into the circulation, transported, and deposited almost exclusively in kidney glomeruli. Intense beta-galactosidase activity was noted in both kidneys with a peak at two weeks following viral administration, concurrent with loss of beta-galactosidase positive hepatocytes. Consistent with our hypothesis of protein transfer, no beta-galactosidase mRNA was detected in glomeruli. Moreover, systemically administered protein generated similar glomerular beta-galactosidase activity. Finally, co-administration of murine CTLA4 Ig, an immunomodulator of T cell activation, with the adenovirus protected infected hepatocytes and markedly diminished glomerular beta-galactosidase activity. Collectively, these findings suggest that a therapeutic protein can be "targeted" to the renal glomerulus, utilizing the liver as a gene transfer organ.

Abatacept↗
PubMed1997

Interleukin-15 signals T84 colonic epithelial cells in the absence of the interleukin-2 receptor beta-chain.

Interleukin-15 (IL-15) shares many biological functions with interleukin-2 (IL-2) due to common receptor components. IL-15 binds to the IL-2 receptor (IL-2R) beta-chain and the common gamma-chain receptor in addition to one other IL-15 binding receptor protein (IL-15R alpha). Both IL-2R beta- and gamma-chains are required to promote cell growth in hematopoietic cells. The colonic cryptlike epithelial cell line T84 contains the common gamma-chain but lacks the IL-2R beta-chain. We report IL-15R alpha-chain mRNA in T84 cells with the use of reverse transcriptase-polymerase chain reaction. T84 and normal colonic epithelial cells bind a FLAG-IL-15 fusion protein in immunoperoxidase and flow cytometric experiments. In addition, IL-15, but not IL-2, accelerates and enhances the development of transepithelial resistance across T84 monolayers in a dose-dependent fashion. We conclude that normal and T84 colonic epithelial cells express IL-15R alpha and are able to bind IL-15. IL-15 can deliver a nonproliferative functional signal in the absence of IL-2R beta-chain in T84 cells.

Cell Division↗
PubMed1996

Partial mediation of glucocorticoid antiproliferative effects by lipocortins.

The glucocorticoids (GCs) dexamethasone (DEX) and prednisolone (PRED), in a concentration-dependent fashion, profoundly inhibit mitogen-induced proliferation of human peripheral blood mononuclear lymphocytes (PBML). This inhibition was specific for GCs, as non-GC steroids were devoid of any antiproliferative capacity. GCs enhanced the mRNA (Northern blot) and protein (Western blot) expression of the calcium and phospholipid binding proteins lipocortin I, II, and V. As a consequence of mitogenic stimulation, PBML secrete PGE2 and leukotriene B4 (LTB4). Antiproliferative concentrations of both DEX and PRED as well as recombinant lipocortin I abolished PGE2 and LTB4 production, suggesting an involvement of lipocortins in GC-mediated antiproliferative effects, possibly by inhibiting eicosanoid production and, consequently, mitogen-induced cellular proliferation. Whereas 5,8,11,14-eicosatetraynoic acid and nordihydroguaiaretic acid mimicked DEX and PRED in inhibiting PGE2 and LTB4 production, neither 5,8,11,14-eicosatetraynoic acid nor nordihydroguaiaretic acid had any effect on mitogen-induced PBML proliferation, indicating that the GC-mediated antiproliferative effect is separate from their effects on eicosanoid release. Furthermore, neutralizing anti-lipocortin I and anti-lipocortin II mAb, while reversing the inhibitory activity of DEX and PRED on PGE2 and LTB4 production, only partially reversed DEX- and PRED-mediated antiproliferative effects. This indicates that the GC-mediated antiproliferative effect is not dependent on inhibition of eicosanoid release by lipocortins and suggests the existence of lipocortin-dependent and lipocortin-independent pathways by which GCs mediate their antiproliferative effects.

5,8,11,14-Eicosatetraynoic Acid↗
PubMed1996

Distribution of IL-15 receptor alpha-chains on human peripheral blood mononuclear cells and effect of immunosuppressive drugs on receptor expression.

IL-15, a newly described cytokine exerting IL-2-like in vitro activities, binds to and induces proliferation of cells co-expressing IL-15R alpha, IL-2R beta, and IL-2R gamma chains. To study the expression of human IL-15R alpha chains, we have utilized tagged human IL-15 protein and FACS analysis. In contrast to resting cells, mitogen-activated macrophages, NK cells, and CD4+ and CD8+ T cells express IL-15R alpha chains. Neither IL-2R alpha nor IL-2R beta chains are required for IL-15 binding. Dexamethasone, but not cyclosporine or rapamycin, blocks mitogen-induced IL-15R alpha expression. Dexamethasone-pretreated cells respond to IL-15 poorly, while the response to IL-2 is not affected. Thus, despite structural and functional similarities between IL-2R alpha and IL-15R alpha chains, the activation-triggered mechanisms of induction are different. Since IL-15R alpha chain is necessary and sufficient for IL-15 binding, regulation of IL-15R alpha expression may represent a new target for T cell-directed pharmacologic intervention.

Base Sequence↗
PubMed1996

Intragraft IL-15 transcripts are increased in human renal allograft rejection.

IL-15, a novel growth factor made by a variety of cells, stimulates T cell proliferation in a fashion similar to IL-2. IL-2 transcripts are not routinely found in rejecting human renal allografts at the time of clinically evident rejection. However, T cell proliferation continues as the rejection progresses. We postulated that IL-15 may be actively transcribed during clinical rejection and account, at least in part, for the ongoing T cell expansion. RNA was extracted from renal biopsies and reverse transcribed to cDNA which was used as template for competitive PCR. IL-2 mRNA was detected in just 3 of the 45 biopsy samples. IL-15 transcripts were detected in all renal biopsy specimens and was significantly increased in specimens obtained from rejecting as compared with nonrejecting renal allografts. IL-15 transcription correlates with rejection and may play an important role in T cell mediated rejection.

Acute Disease↗
PubMed1996

Human immunodeficiency virus type 1 entry into murine cell lines and lymphocytes from transgenic mice expressing a glycoprotein 120-binding mutant mouse CD4.

Human CD4, the receptor for the gp120 envelope glycoprotein of HIV-1, is the route for viral entry into CD4+ cells; other cellular factors may cooperate with CD4 to facilitate HIV-1 entry into human cells. Human CD4 expressed on murine cells does not readily mediate HIV-1 entry, which may reflect a functional incompatibility of human CD4 with murine cellular components. We postulated that a HIV-1 gp120-binding mutant murine CD4 (L3T4) possessing a minimal number of human amino acid residues could facilitate HIV-1 entry into rodent cells, unlike human CD4. This hypothesis led us to develop a series of murine L3T4 mutants that bear human CD4 gp120-binding region amino acid residues while retaining most L3T4 epitopes. HeLa cell transfectants expressing gp120-binding mutant L3T4 proteins could be infected with HIV-1. Three mouse cell lines expressing these L3T4 mutant proteins could also be infected with HIV-1 as determined by PCR techniques that detect viral DNA and spliced RNAs. Lectin-stimulated polymorphonuclear leukocytes from transgenic mice (SBL mouse) expressing a gp120-binding L3T4 mutant protein were infected with HIV-1 at the same frequency as lectin-stimulated human peripheral blood lymphocytes as determined by in situ PCR analyses. Supernatant p24gag and reverse transcriptase levels in HIV-infected mouse cell cultures, however, were routinely at background levels, unlike HIV-infected human cell cultures. Thus, gp120-binding mutant L3T4 proteins mediate viral entry in all mouse cells that were tested, but high-level viral replication is absent in these cells.

Amino Acid Sequence↗
PubMed1996

Recombinant IL-10 and IL-10/Fc treatment down-regulate egg antigen-specific delayed hypersensitivity reactions and egg granuloma formation in schistosomiasis.

In infection with the helminth Schistosoma mansoni, parasite eggs elicit a Th cell-mediated hepatic granulomatous inflammation that leads to scarring, portal hypertension, hemorrhage, and death. On the other hand, the cytokine IL-10 has been shown to decrease egg Ag-specific Th cell responses by down-regulating MHC class II as well as B7 costimulatory molecule expression on accessory cells. We now test the effect of IL-10 in vivo on models of egg Ag-specific hypersensitivity as well as on the natural disease. Systemic administration of IL-10 significantly inhibited delayed-type hypersensitivity reactions to egg Ag as well as primary and secondary granuloma formation to eggs embolized in the lung. However, significant inhibition of hepatic granuloma formation associated with the natural infection required the use of an IL-10/Fc fusion protein with a prolonged in vivo half-life. Lymph node cells from IL-10/Fc-treated mice produced less IL-2 and IFN-gamma, and more IL-4 and IL-10 than control cells, suggesting that reduced egg granuloma formation resulted primarily from down-regulation of Th1 responses. These results indicate that suitable administration of exogenous IL-10 can be effective in ameliorating immunopathologic damage associated with schistosomiasis.

Animals↗
PubMed1996

Irradiated B7-1 transduced primary acute myelogenous leukemia (AML) cells can be used as therapeutic vaccines in murine AML.

Recent studies have shown that tumor cells genetically modified by transduction of B7-1, a natural ligand for the T-cell costimulatory molecules CD28 and CTLA-4, are rejected in syngeneic hosts. In these reports, transformed cell lines and drug-selected cells have been used for vaccinations. To determine the effectiveness of B7-1-transduced primary acute myelogenous leukemia (AML) cells on the induction of antitumor immunity, we have studied a murine AML model in which primary AML cells were retrovirally transduced with the murine B7-1 cDNA. A defective retroviral producer clone expressing B7-1 and secreting a high titer of virus was used for infection of AML cells. Unselected transduced AML cells, expressing a high level of B7-1, were used for in vivo vaccinations. Our results show that one intravenous (IV) injection of irradiated B7-1-positive (B7-1+) AML cells can provide long-lasting (5 to 6 months) systemic immunity against subsequent challenge with wild-type AML cells. Furthermore, one exposure to irradiated B7-1+ AML cells results in rejection of leukemia by leukemic mice when the vaccination occurs in the early stages of the disease. The antileukemia immunity is CD8+ T-cell-dependent and B7/CD28-mediated, since in vivo treatment of mice with anti-CD8 monoclonal antibody or CTLA-4 Ig leads to abrogation of the specific antileukemia immune response. These results emphasize that B7-1 vaccines may have therapeutic usefulness for patients with AML.

Animals↗
PubMed1996

Restricted TCR V beta repertoire in the human mixed lymphocyte reaction is determined by the TCR on the responder cell and not by the stimulating antigen on the stimulator cell.

The use of a restricted TCR repertoire has been reported in antigen-stimulated T cells. We have examined by flow cytometry and polymerase chain reaction the changes in the TCR variable beta (V beta) repertoire as they occur in the mixed leukocyte reaction. The HLA class I-negative lymphoblastoid B cell line, Daudi, an HLA class I-positive variant of the Daudi cell line, and the homozygous typing cell line HTC 9062 were used to stimulate HLA-mismatched responder cells from 8 individuals. The magnitude of HLA incompatibility in various combinations ranged from single DR10 and DR13 differences to full 6-antigen differences at the HLA-A, -B, and -DR loci. Using a panel of 19 V beta-specific oligonucleotide primers, changes in the level of TCR V beta mRNA were assessed. The observed V beta repertoire was not specific for the stimulator cell antigens used. We did not find a correlation between the number of mismatched HLA antigens and the number of V beta elements involved. It rather appeared that individual responder cells displayed a uniform V beta pattern following exposure to single and multiple HLA antigens. We conclude that the V beta repertoire was largely determined by factors associated with the TCR on the responder cells, and not as obviously influenced by the HLA antigen(s) on the stimulator cells.

Antigen Presentation↗
PubMed1996

Cytokine and alloantibody networks in long term cardiac allografts in rat recipients treated with rapamycin.

Treatment with rapamycin (RPM) prevents accelerated rejection of (LEW x BN)F1 cardiac allografts in LEW rats presensitized with BN skin grafts. This study analyzed the influence of RPM on cytokine (IL-2, IL-4, IL-10, and IL-12) and alloantibody networks in this model. Accelerated (24-h) rejection was associated with strong expression of intragraft IL-2 and IL-12 (p40) mRNAs, which reached maximal levels 3 to 6 h post-transplantation. IL-4 and IL-10 mRNAs were readily detectable throughout the observation period. RPM therapy abrogated rejection at 24 h and prolonged cardiac allograft survival to about 50 days. This effect was correlated with a profound initial depression of IL-2 mRNA; delayed expression of IL-2 mRNA was detected in well functioning grafts at > 20 days. In RPM-treated hosts, expression of IL-12 (p40) mRNA was low at the early time points (6-24 h), but prominent in long term grafts. The expression of both IL-4 and IL-10 mRNAs was preserved in RPM-conditioned hosts. Immunohistologic analysis of long term allografts revealed an interstitial cellular infiltrate and areas of intimal proliferation within small arteries indicative of early transplant arteriosclerosis. Analysis of cytokine proteins showed dense labeling of mononuclear and some endothelial cells for IL-4 and IL-12 (p70), but not for IL-2 or IFN-gamma alloantibody in the early post-transplant period. However, an increase in circulating and intragraft IgM and, to a lesser extent, IgG, primarily of the IgG2b subclass, was evident in long term recipients. Thus, RPM treatment reduces, but does not completely inhibit, the expression of Th1-type and preserves the expression of Th2-type cytokines. The demonstration of IL-12 in long term allografts after RPM therapy may reflect late activation of macrophages that, coupled with the appearance of IgG2b, may contribute to the chronic rejection of cardiac allografts.

Animals↗
PubMed1996

Immunosuppressants: cellular and molecular mechanisms of action.

The basic immunosuppressive protocol used in most transplant centers involves the use of multiple drugs, each directed at a discrete site in the T-cell activation cascade and each with distinct side effects. Cyclosporine, azathioprine, corticosteroids, FK506 (tacrolimus), and RS61443 (mycophenolate mofetil) have been approved by the Food and Drug Administration, and the clinical efficacy of rapamycin (sirolimus), mizoribine, 15-deoxyspergualin, and leflunomide is being explored. Based on their primary site of action, the immunosuppressants can be classified as inhibitors of transcription (cyclosporine, tacrolimus), inhibitors of nucleotide synthesis (azathioprine, mycophenolate mofetil, mizoribine, leflunomide), inhibitors of growth factor signal transduction (sirolimus, leflunomide), and inhibitors of differentiation (15-deoxyspergualin). Polyclonal antilymphocyte antibodies, monoclonal antibodies directed at the T-cell antigen receptor complex (OKT3, TIOB9), and monoclonal antibodies directed at additional cell surface antigens, including interleukin-2 receptor alpha, afford cell-specific regulation of the immune response and are being used in the clinical setting as induction therapy and/or antirejection drugs. Clearly, the transplant clinician now has a greater choice in the selection and application of immunosuppressants in the clinic for the fine regulation of the antiallograft repertory. The prevailing paradigm regarding the mechanisms of action of immunosuppressants is that they all function to prevent allograft rejection by preventing/inhibiting cell activation, cytokine production, differentiation, and/or proliferation. One hypothesis, albeit provocative, is that some of the immunosuppressants might function by stimulating the expression of immunosuppressive molecules and/or cells.

Humans↗