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Biomedical subjects

A D Hess

Publications and source records attributed to A D Hess.

At least 55 records · Page 3Linked to original sources
PubMed1993

Autologous graft-vs-host disease: mechanisms and potential therapeutic effect.

Administration of the immunosuppressive drug cyclosporine (CsA) after autologous or syngeneic bone marrow transplantation (BMT) elicits an autoimmune syndrome with pathology identical to graft-vs-host disease (GVHD). This syndrome can be induced both in man and in rats and is associated with the development of cytolytic autoreactive T cells that recognize MHC class II determinants. Studies in a rat model suggest that there are two essential components necessary for the induction of an autologous/syngeneic GVHD and include the inhibition of thymic dependent clonal deletion of autoreactive T lymphocytes by CsA and the elimination of a peripheral regulatory mechanism by the preparative regimen. The absence of peripheral autoregulation creates a permissive environment for the activation of the autoreactive T cells. Based on our understanding of the immunobiology of this autoimmune syndrome, we have utilized the induction of autologous/syngeneic GVHD in an attempt to provide an antitumor therapeutic effect after autologous BMT. Interim analyses of our clinical trials suggest that this approach is quite promising.

Animals↗
PubMed1993

Lymphocyte depletion in bone marrow transplantation: will modulation of graft-versus-host disease prove to be superior to prevention?

Despite its detrimental effects, graft-versus-host disease (GVHD) has antileukemic properties as evidenced by a lower relapse rate in patients who develop GVHD following allogenic bone marrow transplantation. Meaningful long-term survival may be achieved if this latter property can be retained at the same time that the deleterious immune sequelae of acute and chronic GVHD are diminished. This is the focus of several recent graft engineering protocols. Various bone marrow components (lymphocytes, hematopoietic stem cells, and committed progenitor cells) can now be isolated and then used to reformulate the marrow graft. Combined with host immunosuppression or cytokine augmentation, it now may be possible to modulate GVHD such that its beneficial properties are enhanced without incurring its life-threatening side effects.

Animals↗
PubMed1992

Induction of cutaneous graft-versus-host disease by administration of cyclosporine to patients undergoing autologous bone marrow transplantation for acute myeloid leukemia.

Cutaneous graft-versus-host disease (GVHD) has been reported after administration of cyclosporine (CSP) after autologous bone marrow transplantation (ABMT) with unpurged marrow in patients with lymphoma. To determine whether GVHD can be induced after ABMT with chemopurged marrow in acute myeloid leukemia (AML), we administered intravenous CSP for 28 days (beginning on the day of ABMT) to 19 patients with AML (12 in first remission [CR1], six in CR2, and one in CR3) who received busulfan (16 mg/kg) and cyclophosphamide (200 mg/kg) and ABMT with 4-hydroperoxycyclophosphamide (4HC)-treated marrow. In this dose-escalation trial, CSP daily doses were 1 mg/kg in seven patients, 2.5 mg/kg in eight patients, or 3.75 mg/kg in four patients. Skin biopsies were obtained weekly after ABMT or on appearance of rash and were graded for GVH changes. Overall, 15 of 19 patients (79%) had cutaneous histopathologic grade 2 GVHD at a median of 33 days (range, 14 to 49) after ABMT; in 10, cutaneous manifestations were present at time of positive biopsy. The frequency, time to onset, and duration of GVHD were similar among the three CSP dosage groups. No patients had hepatic or gastrointestinal dysfunction attributable to GVHD or required specific therapy for GVHD. Positive biopsies for GVHD were seen in seven of eight patients who received full-course, full-dose CSP and 8 of 11 patients who had CSP discontinued or dosage reduced because of renal insufficiency. Three patients (one with positive biopsy) died with ABMT-related complications. Seven patients (four CR1, three CR2) relapsed with AML at a median of 411 days (range, 178 to 549) after ABMT; six of seven had positive biopsies for cutaneous GVHD. Nine patients (seven CR1, one CR2, and one CR3) are alive without relapse at a median of 501+ days (range, 252+ to 811+) after ABMT; eight of nine had cutaneous GVHD. Short-course CSP can induce autologous GVHD in recipients of chemopurged marrow autografts for AML, but randomized prospective trials are needed to determine whether this immunologic reaction is associated with alterations in leukemic relapse rate and disease-free survival after ABMT in AML.

Adolescent↗
PubMed1992

Thalidomide for the treatment of chronic graft-versus-host disease.

BACKGROUND: Allogeneic bone marrow transplantation is an accepted therapy for hematologic cancer, aplastic anemia, and inherited immunodeficiencies. Chronic graft-versus-host disease (GVHD) is the principal complication in patients surviving more than 100 days. Thalidomide has been shown experimentally to be effective in treating GVHD. METHODS: We treated 23 patients with chronic GVHD refractory to conventional treatment and 21 patients with "high-risk" chronic GVHD (identified as having at least two of the following three risk factors: chronic GVHD that has evolved from acute GVHD, lichenoid skin or mucous-membrane changes, and hepatic dysfunction. Such patients have a high mortality rate.) with thalidomide in a dose that produced a plasma level of 5 micrograms per milliliter two hours after administration. Therapy was continued for three months after a complete response or for six months after a partial response. RESULTS: The overall actuarial survival of all enrolled patients was 64 percent. Survival was 76 percent among the patients receiving salvage therapy for refractory GVHD and 48 percent among those with high-risk GVHD. A complete response was observed in 14 patients, a partial response in 12 patients, and no response in 18. Side effects were minor, most notably sedation in almost all patients. CONCLUSIONS: In this preliminary trial, thalidomide appeared to be safe and effective for the treatment of chronic GVHD. A trial comparing thalidomide with prednisone in patients with newly diagnosed chronic GVHD will be required to demonstrate its relative efficacy.

Adolescent↗
PubMed1992

Autologous graft-versus-host disease: a novel approach for antitumor immunotherapy.

Autologous bone marrow transplantation (BMT) is a therapeutic option for the treatment of lymphohematopoietic malignancies and solid tumors. Despite the intensive cytoreductive therapy, however, the rates of tumor recurrence after autologous BMT remain unacceptably high. Current studies suggest that the administration of cyclosporine (CsA) disrupts the reconstitution of self-tolerance following autologous BMT leading to the induction of an autoimmune graft-versus-host disease (GVHD). Studies in a rat tumor model and preliminary clinical trials suggest that this autoimmune or autologous GVHD provides a significant antitumor effect. Moreover, the antitumor effect of autologous GVHD can be enhanced by administration of gamma-interferon, which upregulates the antigen recognized by the autoreactive effector cells of autologous GVHD. These studies indicate that the induction of an autoimmune GVHD after autologous BMT may be a promising immunotherapeutic approach for treatment of certain neoplastic diseases.

Animals↗
PubMed1992

Interferon-gamma potentiates the antitumor effect of cyclosporine-induced autoimmunity.

Graft-versus-host-disease (GVHD), which results after allogeneic bone marrow transplantation (BMT), is associated with reduced leukemic relapse. This may be mediated by an immunologic attack with subsequent destruction of residual tumor cells. On the other hand, GVHD does not normally occur after autologous BMT (ABMT), which has an inherently high relapse rate. However, an autoimmune syndrome (AIS) similar to GVHD can be induced after autologous/syngeneic BMT by administration of cyclosporine-A (CsA), resulting in the production of major histocompatibility complex (MHC) class II or Ia autoreactive cytolytic effector cells. Since many hematopoietic malignancies express variable levels of class II molecules, we hypothesized that the adjuvant use of interferon-gamma (IFN-gamma) with CsA-induced autoimmunity after autologous/syngeneic BMT may upregulate class II antigens on residual tumor cells and make them more susceptible to attack by the Ia-reactive cells of CsA-induced AIS. The present studies demonstrated that the CsA-induced autoimmune syndrome mediated an anti-tumor effect, although this effect was dependent on challenge with a minimal number of tumor cells. Further studies clearly demonstrated that the antitumor effect could be markedly enhanced by administration of IFN-gamma which increased the susceptibility of the tumor to recognition and lysis by the CsA induced autoimmune effector cells. The induction of MHC class II-restricted AIS similar to GVHD by administration of CsA together with the ability to manipulate the surface phenotype of residual tumor cells may lead to decreased relapse rates in the ABMT setting.

Animals↗
PubMed1991

Response of Jurkat T cells to phorbol ester and bryostatin. Development of sublines with distinct functional responses and changes in protein kinase C activity.

T lymphocyte activation is initiated as a result of the interaction between the TCR complex and Ag as seen in the framework of a membrane-bound MHC molecule. Receptor stimulation results in a rise in free intracellular Ca2+ and the activation of protein kinase C (PKC). Bryostatin (Bryo) and phorbol esters (e.g., 12-O-tetradecanoylphorbol 13-acetate (TPA] are PKC activators with somewhat different immunologic effects. We compared the effect of Bryo and TPA on the T cell tumor line Jurkat and derivatives of Jurkat cells grown in media supplemented with 100 nM Bryo ("BR100" cells) or 100 nM TPA ("TP100" cells). In untreated Jurkat cells, there is a dose- and time-dependent decrease in proliferation, compared to media controls, after the administration of as little as 10 nM TPA. This can be reversed in a dose- and time-dependent manner by Bryo. Interestingly, the expression of the transferrin receptor parallelled this effect on proliferation. Furthermore, Jurkat cells grown continuously in 100 nM TPA regained full proliferative capacity after several weeks in culture and transferrin receptor expression returned to near the level seen in untreated Jurkat cells. The chromatographic separation of PKC activity in these three cell lines showed that total PKC activity was dramatically decreased in both the TP100 and BR100 cells when compared to untreated Jurkat cells. However, in the TP100 cells there exists a peak of activity that is activated by Bryo, but not TPA. Western blots of whole cell lysates of the three cell lines showed that PKC-alpha and PKC-beta II were both down-regulated in BR100 and TP100 cells compared to untreated Jurkat cells. PKC-gamma was not detected in any of the cell lines. Therefore, the Bryo-specific peak seen in TP100 cells may be PKC-delta, -epsilon, -zeta, -eta, or a novel PKC isoform. This could provide the basis for a molecular characterization of the differences in PKC activation between phorbol esters and Bryo.

Antigens, CD↗
PubMed1991

Successful treatment of murine melanoma with bryostatin 1.

Bryostatins are a novel class of protein kinase C activators which were isolated from the marine bryozoan Bugula neritina and found to possess both antineoplastic and immunoenhancing properties. In this report, we examined the relationship between the in vivo and in vitro antineoplastic effects of bryostatin 1. The in vivo antitumor activity of bryostatin 1 was demonstrated in a B16 melanoma pulmonary metastases model, in which treatment of tumor-bearing C57BL/6 mice with 5 days of bryostatin 1 resulted in a significant reduction in of the number of lung nodules (control, 87; bryostatin, 7). There was a clear dose-response effect, with the optimal antimelanoma dose being 100 micrograms/kg/day, but even low doses of bryostatin 1 of 1 micrograms/kg/day resulted in a 53% reduction in the number of metastases. Although bryostatin 1 shares many biological properties with the phorbol esters, parallel treatment with 12-O-tetradecanoyl 13-phorbol acetate was ineffective against B16 melanoma in vivo. Using a clonogenic assay, bryostatin 1 was found to have a direct antiproliferative effect against B16 melanoma. This inhibition occurred at relatively high bryostatin 1 concentrations (10(-6) M), in comparison with a sensitive cell line REH (10(-10) M). Treatment of mice with bryostatin 1 or preincubation of normal spleen cells with bryostatin 1 failed to enhance nonspecific cell-mediated cytotoxicity against B16 melanoma in vitro. Moreover, bryostatin 1 was found to inhibit both natural killer cell activity and interleukin 2 generation of lymphokine-activated killer cells. Thus, a role for an in vivo immune enhancement mechanism as the basis for the antimelanoma activity observed with bryostatin 1 cannot be invoked from these experiments. These findings indicate that bryostatin 1 may act directly on the B16 melanoma pulmonary metastases. The precise mechanism whereby bryostatin exerts its antimelanoma effects remains unclear.

Animals↗
PubMed1991

Effect of cyclosporine on T lymphocyte development. Relationship to syngeneic graft-versus-host disease.

This report investigates the effects of cyclosporine on the reconstitution of T lymphocytes after syngeneic bone marrow transplantation and its role in the development of a novel T cell-mediated autoimmune disease, syngeneic graft versus host disease. We analyzed the effect of CsA treatment on T lymphocyte differentiation during reconstitution after bone marrow transplantation and correlated the maturation of CD4+ and CD8+ T cell subsets with the onset of syngeneic GVHD. Administration of CsA following syngeneic bone marrow transplantation leads to a developmental arrest of mature CD4+ and CD8+ T lymphocytes in the thymus and a marked reduction in cells expressing the alpha beta T cell receptor. The reduction of CD4+ and CD8+ T cell subsets is also reflected in the peripheral lymphoid compartment with an altered CD4/CD8 ratio. Functional assessment of the cells revealed that CD8+ cells respond normally to mitogenic signalling whereas CD4+ cells exhibit marginal proliferative responses. Both subsets of T lymphocytes respond to syngeneic B lymphoblasts, comparable to the response of T lymphocytes from non-CsA-treated syngeneic BMT recipients, suggesting that autoreactive cells are produced despite CsA treatment. Following discontinuation of CsA, T cell differentiation in the thymus is rapidly restored to normal. However, concurrent with the onset of syngeneic GVHD, a compensatory insurgence of CD4+ T helper cells is observed.

Animals↗
PubMed1991

The effect of the CD28 activation pathway on the immunosuppressive action of cyclosporine.

The effect of the CD28 activation pathway on the immunosuppressive action of CsA was assessed. Human peripheral blood lymphocytes were stimulated with anti-CD3, bryostatin (Bryo) a novel activator of protein kinase C (PKC) and anti-CD28 singly or in combination, to which graded doses of CsA were added to determine relative sensitivity. Proliferation, IL-2 production, and IL-2 receptor expression were assessed and the IC50 determined. Lymphocytes stimulated with Bryo exhibited a marginal proliferative response but expressed the IL-2 receptor despite the presence of CsA. Addition of anti-CD3 or anti-CD28 to Bryo-stimulated lymphocytes promoted a vigorous proliferative response. CsA effectively inhibited the proliferative response and IL-2 production induced with anti-CD3 and Bryo but did not inhibit the response of cells stimulated with anti-CD28 and Bryo. However, II-2 receptor expression in both sets of cultures were comparable due to the induction of IL-2 receptor by Bryo and was not inhibited by CsA. Costimulation of lymphocytes with anti-CD3 plus anti-CD28 resulted in a 2-3-fold enhancement of proliferation compared with lymphocytes stimulated with anti-CD3 alone. Addition of CsA to lymphocytes stimulated with anti-CD3 resulted in the dose-dependent suppression of the proliferative response and IL-2 production (IC50 = 10-25 nM) but less so for IL-2 receptor expression (IC50 = 100-150 nM). In comparison, the proliferative response and IL-2 production elicited by anti-CD3 + anti-CD28 was more resistant to the effects of CsA (IC50 = 100-200 nM). However, IL-2 receptor expression exhibited comparable sensitivity to CsA (IC50 = 100-200 nM) in the presence of anti-CD28. Combination drug:drug studies revealed that CsA and the protein kinase C inhibitor H-7 were additive for both anti-CD3 and anti-CD3 plus anti-CD28 response. On the other hand, the cGMP-dependent protein kinase inhibitor H-8 was synergistic with CsA in inhibiting the response of lymphocytes to anti-CD3 plus anti-CD28 but only additive for responses to anti-CD3. Taken together, these data suggest that CsA inhibits T cell activation at two distinct levels, leading to inhibition of IL-2 production and inhibition of IL-2 receptor expression. Activation of the CD28 pathway partially overcomes the inhibitory activity of CsA on IL-2 production and may be mediated by indirect activation of a cGMP-dependent protein kinase.(ABSTRACT TRUNCATED AT 400 WORDS)

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1991

Prevention of syngeneic graft-versus-host disease by recovery of thymic microenvironment after cyclosporine.

Following a course of cyclosporine, syngeneic rat radiation chimeras consistently develop a GVHD-like syndrome. Correlation of the thymic immunopathology with conditions leading to syngeneic graft-versus-host disease (sGVHD) suggested the hypothesis that reconstitution of the normal thymic microenvironment after CsA is necessary for self-tolerance. When thymic regeneration is impaired, as in rats receiving previous mediastinal irradiation, then self-reactive effector cells are not regulated and proceed to damage the target tissues. Alternately, it could be argued that the observed thymic abnormalities are irrelevant to sGVHD. To test the primary hypothesis, post-CsA thymic reconstitution was prevented by total thymectomy in unirradiated rats. These rats consistently developed acute type sGVHD seen at 7 and 21 days post-CsA while rats from the CsA-treated sham thymectomy control group failed to develop sGVHD. Because thymectomy prior to CsA blocks sGVHD, most likely the peripheral effector cells in the post-CsA thymectomy group were derived from the CsA-altered thymus. The absence of sGVHD in the sham group indicates that the thymus led to active regulation of these cells after stopping CsA. If regeneration of the thymus restored only negative selection, then the sham thymectomy group should have also developed sGVHD. Flow cytometry and morphology of the spleen and lymph nodes demonstrated that the thymectomized rats, like CsA-treated radiation chimeras, experienced a significant delay in maturation of T cells following CsA. In contrast to the usual model in radiation chimeras, however, the post-CsA thymectomized rats did not convert to chronic type sGVHD. The importance of an abnormal thymus for this transition was confirmed in syngeneic radiation chimeras. Thymectomy after CsA in these rats also blocked the rapid transition to chronic sGVHD.

Acute Disease↗
PubMed1990

Effector mechanisms in cyclosporine A-induced syngeneic graft-versus-host disease. Role of CD4+ and CD8+ T lymphocyte subsets.

Syngeneic graft-versus-host disease (SGVHD) is a T cell-mediated autoimmune disease occurring postsyngeneic bone marrow transplantation and the administration of the potent immunosuppressive agent, cyclosporine A. Paradoxically, cyclosporine A disrupts the immunologic homeostasis governing self-tolerance. Our studies using an adoptive transfer model attempted to identify effector mechanisms associated with the autoimmune disease. Both CD4+ and CD8+ splenic T cells isolated from autoimmune donors were required for the adoptive transfer of active disease into lethally irradiated secondary recipients reconstituted with normal bone marrow. Doses of more than 5 x 10(6) of nylon wool depleted splenocytes from autoimmune donors effectively transferred disease into lethally irradiated secondary recipients. Splenocytes that are T cell depleted or CD4(+)-enriched cells did not elicit disease upon adoptive transfer. Nylon wool fractionated CD8+ splenocytes also failed to adoptively transfer disease unless high doses (greater than or equal to 30 x 10(6)) were used. The disease transferred with the CD8+ subset presented as acute type SGVHD and was self-limiting. The recombination of the individually isolated T cell subsets not only restored but also enhanced immune reactivity upon adoptive transfer. Moreover, use of the recombined subsets resulted in progressive disease with the development of chronic type SGVHD. The titration of each subset to the other suggested that a minimal number of CD4+ T cells was required to potentiate the CD8+ autoreactive cells in vivo. Further analysis of the helper cell involved demonstrated that it had a CD4+ CD45r- phenotype, characteristic of an amplifying helper cell population. Administration of IL-2 did not substitute for CD4+ Th cells but yet amplified the activity of unfractionated cells or recombined subsets implicating the role of other factors in the pathogenesis of SGVHD. Delineation of the effector mechanisms involved in SGVHD is critical in determining the underlying events that trigger either the production of autoreactive cells or the perturbation of the regulation of these autoreactive cells, culminating in autoimmunity.

Animals↗