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J Steinmann

Publications and source records attributed to J Steinmann.

At least 55 records · Page 3Linked to original sources
PubMed1995

Leukemia-specific allogeneic donor T cells: quantification by limiting dilution assay.

Allogeneic T cells are capable of discriminating between leukemia cells and non-malignant hematopoetic cells. This has been concluded from clinical BMT data and demonstrated by in vitro experiments. We analyzed the frequency and specificity of leukemia-reactive T cells from syngeneic and allogeneic blood donors by limiting dilution assays for interleukin-2-producing (TH1) and cytotoxic (CTLp) T cells. Target cells were leukemia blasts obtained from a patient with common ALL. Control targets were generated by EBV transformation. Effector cells were generated from the peripheral blood of the patient in remission, from his syngeneic brother and from eight healthy, HLA-mismatched volunteers. The effector cells were stimulated with leukemia cells and interleukin-2. Neither the patient nor his brother were able to generate anti-leukemic CTLp or TH1. The HLA-mismatched allogeneic donors displayed anti-leukemic CTLp frequencies with a range from 0 to 68 million. TH1 cells with anti-leukemic specificity were not detectable. We conclude that there are great inter-individual differences in the GVL potential of fully allogeneic peripheral T lymphocytes. It is possible to identify T cell lines with reactivity against leukemia blasts and non-reactivity against normal hematological cells from the same individual. These cell lines are potential effector cells for immunotherapy of human leukemia.

Blood Donors↗
PubMed1995

Allogeneic mouse T cell lines distinguish three Balb/c leukemias from each other and from non-leukemic lymphocytes.

In order to separate graft-versus-leukemia (GVL) effect from graft-versus-host (GVH) reactions in allogeneic cell therapy, we established cytotoxic T cell lines (CTL) against irradiated A20, WEHI-3 and PU cells, ie cells from 3 hematopoietic tumors of Balb/c origin. Immunization with these cell lines did not lead to prolonged survival in Balb/c mice. The cytotoxic activity of the CTL was tested against the 3 leukemias. In all 9 combinations the highest specific lysis was achieved against the stimulating tumor. Cold target inhibition experiments showed that the activity against 51Cr-labelled leukemia cells could be almost completely inhibited by adding a sufficient amount of unlabelled target cells. On the other hand, when unlabelled concanavalin A-induced Balb/c blast cells were added, the inhibition was incomplete. By means of flow cytometry it was excluded that the different susceptibilities and inhibitory potentials of tumor cells and nonmalignant blasts are caused solely by differences in the MHC expression of the target cells. These findings confirm that allogeneic CTL are capable of discriminating malignant from nonmalignant cells, even if the tumor is nonimmunogenic in syngeneic animals.

Animals↗
PubMed1994

Failure of in vitro T-cell assays to predict clinical outcome after human kidney transplantation.

Allotransplant rejection is a T-cell-dependent reaction. Functional in vitro T-cell assays are being used widely for donor-recipient matching in bone marrow transplantation and have recently been used in some centres for transplant monitoring. In order to assess tolerance induction after clinical transplantation, we measured the T-cell response of the host against donor spleen cells of 33 kidney transplant patients before and every 3 months after transplantation over a period of 18 months. The T-cell reactivity before transplantation was not significantly different in any of the assays in rejecting and non-rejecting patients. In the classical mixed lymphocyte culture (MLC), a donor-specific loss of reactivity was seen only in a patient with a CMV-associated irreversible transplant rejection. One patient with chronic rejection acquired a very high MLC response against donor spleen cells and a high response against third-party cells. Little or nonspecific changes were seen in the MLCs of all other patients. Using the method of limiting dilution analysis (LDA), we found a significant reduction of donor-specific cytotoxic T-cell precursors (CTL-p) within the first 3 months after transplantation in most patients with high antidonor CTL-p frequencies before transplantation. The reduction of donor-specific CTL-p was seen in patients with rejection episodes as well as in patients without. Thus we conclude, in contrast to others, that MLC and CTL-p LDA have no predictive value on the outcome of clinical transplantation.

Clonal Deletion↗
PubMed1994

Comparison of two Cobas Core enzyme immunoassays with other test systems for the detection of cytomegalovirus-specific IgG and IgM antibodies.

The new Cobas Core CMV IGM and IgG enzyme immunoassays (Roche Diagnostic Systems, Basle, Switzerland) were evaluated for their ability to detect cytomegalovirus (CMV)-specific IgM and IgG antibodies. Therefore, both were compared with some other commercially available and already established serological tests used in the laboratory diagnosis of CMV infection. These included the Abbott IMx CMV IgM and IgG assays, the Abbott CMV-M EIA, the Gull CMV IgM and IgG immunofluorescence tests, the medac CMV-IgM-ELA, and the Enzygnost anti-cytomegalovirus assay (Behringwerke). A total of 572 serum samples of various categories were examined and the results showed high concordances between all methods, ranging from 84.5% to 94.9%.. In a follow-up on renal transplant patients, the times of first detection of seroconversions were compared. Since a high overall agreement between the Cobas Core CMV IgM and IgG enzyme immunoassays and the other test systems were observed, these new assays represent useful and reliable tools for clinical CMV diagnosis.

Antibodies, Viral↗
PubMed1993

Interaction of papain-digested HLA class I molecules with human alloreactive cytotoxic T lymphocytes (CTL).

Acute immunological rejection events of transplanted allogeneic organs are strongly dependent on T cell reactivity against foreign MHC products. The recognition requirements of alloreactive cytotoxic T cells are of particular interest for finding approaches to modulating alloreactivity. The role of the allogeneic MHC molecule itself and/or an associated peptide in the interaction with the T cell receptor is still, however, unclear. Our studies have focused on the interactions of papain-digested HLA class I molecules with alloreactive CD8+ CTL. These polypeptides, consisting of the polymorphic alpha 1 and alpha 2 and the monomorphic alpha 3 domains, were used in both soluble and immobilized form to study their functional effects on anti-HLA-A2 reactive CTL. Purified polypeptides were of molecular mass 32-34 kD. HLA-A2 polypeptides (0.55 micrograms/ml) in soluble form induced half-maximal reduction of CTL cytotoxicity. These concentrations were quantitatively comparable to the effective doses of intact HLA class I molecules, which contain the hydrophobic transmembrane domain and the intracytoplasmic tail. In addition, specific activation requirements of these CTL were investigated in a serine esterase release assay. Maximal degranulation was observed after 2 h of antigen contact. Purified HLA class I molecules allospecifically activated the anti-HLA-A2 CTL to degranulate serine esterase, when immobilized on plastic microtitre plates. Thus, polypeptides containing the polymorphic alpha 1 and alpha 2 domains of human class I molecules potentially modulate the cytotoxic T cell response. This might have implications for the reduction or prevention of allograft rejection in recipients of foreign organs.

Cytotoxicity, Immunologic↗
PubMed1993

Interleukin-4 bypass of the immunosuppressive effect mediated by interleukin-2 receptor antibodies.

Numerous studies have demonstrated that the generation of alloreactive effector cells depends on cytokines. Conversely, there is evidence that cytokine metabolism is altered at the clonal level in tolerant chimaeras. This has led to preclinical and clinical studies using antibodies that antagonize interleukin-2 (IL-2), with the hope of achieving immunosuppression and inducing tolerance. Monoclonal antibodies against the alpha-chain (p55) of the human IL-2 receptor are being applied to prevent transplant rejection and graft-versus-host disease in several clinical trials. The antibodies that have been applied clinically so far antagonize the binding of IL-2 to the IL-2 receptor alpha-chain which is part of the high affinity IL-2 receptor, but they do not deplete the receptor-bearing cells. Our study investigates the immunosuppressive effect of monoclonal antibodies against the alpha-chain (p55) and beta-chain (p75). In mixed lymphocyte cultures the p55 antibody causes a reduction in T-cell proliferation to about 50%. The generation of cytotoxic T cells is reduced more effectively (up to 80%). By additional blocking of the IL-2 receptor beta-chain we achieved an additional but still incomplete immunosuppressive effect. Moreover we show that IL-2 receptor-blocked alloreactive T cells escape suppression by using IL-4 as an alternative stimulating signal. To prevent T lymphocytes benefiting from this alternative and thwarting the immunosuppressive effect, cytotoxic IL-2 receptor antibodies that deplete the high affinity receptor-bearing cells are needed.

Antibodies↗
PubMed1993

Non-invasive three-dimensional localisation of arrhythmogenic foci in Wolff-Parkinson-White syndrome and in ventricular tachycardia by radionuclide ventriculography: phase analysis of double-angulated integrated single photon emission computed tomography (SPECT).

A new tomographic technique combined with phase analysis was used to detect premature and ectopic ventricular contraction patterns in 15 patients with Wolff-Parkinson-White syndrome and during ventricular tachycardia in seven patients. Data generated by gated single-photon emission computed tomography (SPECT) were analysed by backprojection of the Fourier coefficients, double-angulation, and integration to thick slices containing the ventricles, thus allowing visualisation of the contraction patterns in three perpendicular views. The results were compared with those of catheter mapping. In nine patients with Wolff-Parkinson-White syndrome the site of initial contraction detected was identical with the site of the accessory pathway found by catheter mapping. The sites of origin of the ventricular tachycardias determined by catheter mapping were within 3 cm of the sites detected by the new technique. This new technique seems to be a promising non-invasive method for localising ectopic ventricular activity that will considerably shorten the time required for subsequent invasive procedures.

Adult↗
PubMed1992

Influence of cell dose and graft-versus-host reactivity on rejection rates after allogeneic bone marrow transplantation.

The number of cells transplanted and their capacity to induce graft-versus-host reactivity (GvHR) are two factors that are suspected to influence the engraftment of allogeneic bone marrow. We have investigated their impact on graft rejection rates in busulfan-treated LEW rats. In a series of experiments, we varied (1) the number of marrow cells transferred (1, 5, 10, 20, 30, and 40 x 10(7)), (2) the degree of pretransplant immunosuppression (1.5, 3.0, and 4.5 Gy of total body irradiation [TBI]; 0, 30, 60, 90, 120, and 180 mg/kg cyclophosphamide), and (3) the ability of the marrow graft to induce classical GvHR against major histocompatibility complex (MHC) antigens [semiallogeneic (CAP x LEW)F1 or CAP rats as marrow donors]. Reducing either the immunosuppressive pretreatment or the number of cells transplanted resulted in a stepwise increase in rejection rates. However, every reduction in the size of the marrow inoculum was compensated by increased immunosuppression and vice versa. While 60 mg/kg cyclophosphamide was sufficient to prevent rejections after grafting of 40 x 10(7) cells, 90 mg/kg was necessary to ensure 100% engraftment after transplantation of 20 x 10(7) cells, 120 mg/kg after 10 x 10(7) cells, and 180 mg/kg after 1 x 10(7) cells. Since CAP marrow leads to GvHR-mediated immunosuppression in LEW recipients, in contrast to (CAP x LEW)F1 marrow, we had supposed that lower cell numbers or cyclophosphamide doses are sufficient to achieve engraftment of CAP marrow. Although severe GvHR was present in all animals receiving escalating doses of CAP cells, the rejection rates were the same as for (CAP x LEW)F1 marrow. In conclusion, we have demonstrated that there is a sensitive balance between the immunosuppression of the host and the number of marrow cells transferred. We were not able to number of marrow cells transferred. We were not able to detect a beneficial effect of classical GvHR against MHC antigens on the engraftment of allogeneic marrow. Thus, our results do not support the hypothesis that the loss of GvHR-mediated immunosuppression is responsible for higher rejection rates following transplantation of T-cell-depleted bone marrow.

Animals↗
PubMed1992

Rejection prophylaxis with interleukin-2 receptor antibody BT 563: mechanisms of action on human cells.

We investigated the in vitro immunosuppressive effect of BT 563, a monoclonal antibody, against the alpha-chain of the human interleukin-2 (IL-2) receptor (p 55), which has been used to prevent transplant rejection in several clinical trials. We also measured the proliferative T cell alloresponse and pCTL frequencies of BT563-treated kidney transplant patients. In mixed lymphocyte cultures BT 563 caused a reduction of T cell proliferation to about 50%. This could not be reversed by the addition of exogenous IL-2. A more effective reduction (80%) was seen in the generation of cytotoxic T cells from CML cultures and at the clonal level. The specific T cell response after preincubation with antigen and BT 563 was not reduced so that BT 563 did not induce tolerance. The in vitro findings indicated that BT 563 had a significant but incomplete immunosuppressive effect. This correlated with the clinical course and ex vivo analysis of PBL from BT 563-treated patients after kidney transplantation.

Antibodies, Monoclonal↗
PubMed1992

Cytokeratin filaments of the liver of BALB/c mice as a sensitive marker of liver damage. Computer-aided characterization with the image analysing system "IBAS".

The cytoskeleton forms a complex structural network which is of major importance for both structural integrity and physiologic functions of the cell. The aim of the present investigation was to investigate whether hepatotoxic effects of nitrosamine and colchicine can be detected through changes in the cytokeratin filament system which is an important component of the cytoskeleton. Groups of 10 male and 10 female newborn BALB/c mice were treated with either 25 micrograms dimethylnitrosamine (DMN) injected intraperitoneally on the day of birth; or with a daily subcutaneous injection of 0.12 micrograms/kg b.w. colchicine starting at ten weeks of age. A third group of mice served as untreated controls. All animals were held under standard laboratory conditions until necropsy at 16 weeks of age. The group injected with DMN received 0.05% phenobarbital with their drinking water after weaning. The histologic changes in the liver tissue were characterized by light microscopy. Changes of the cytokeratin filaments were visualized by the indirect immunofluorescent technique and quantified by using the image analysing system "IBAS". The cytokeratin filaments in the DMN group were markedly increased in amount and had a variety of morphological alterations. These effects could be measured quantitatively and did not indicate any sex-dependent behavior. The colchicine group did not display any structural changes in the cytokeratin filaments but sex-dependent changes in the amount of keratin material was revealed by image analysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Actin Cytoskeleton↗
PubMed1992

Acute and mid-term experiences with the Wiktor stent in acute complications and restenosis after coronary angioplasty.

We report about the 6-month follow-up of 28 consecutive patients treated with a new tantalum stent (Wiktor¿ stent, Medtronic, Inc.). Indication for stenting was the prevention of restenosis in eight patients (restenosis group), and threatening or acute closure after PTCA in 20 patients (acute closure group). Twenty-eight of 30 stents were successfully positioned in 27 of 28 patients (96%), whereas implantation failed twice in one patient. Immediate stent occlusion developed in two patients in the acute closure group (7.4%) Subacute stent occlusion was observed in three patients (11%), one in the restenosis group, two in the acute closure group, between 3 and 5 days after implantation. Coronary bypass surgery had to be performed in four patients (15%): one patient after failed stent placement, two after acute, and one after subacute stent thrombosis. Major bleeding complications related to the anticoagulative drug regimen occurred in nine patients (33%). Three patients (11%) died for reasons most probably not related to stent implantation. A 6-month angiographic follow-up revealed restenosis in two of 19 patients (11%), one patient in each group. Sixteen of the 27 stented patients (59%) reached 6-month follow-up without death, acute or subacute stent thrombosis, or restenosis. It is concluded that the Wiktor stent can be placed with a high rate of success. It may also reduce the risk of restenosis. The stent also offers the possibility to circumvent emergency bypass surgery in case of PTCA related vessel occlusion. Acute and subacute stent occlusion still remains an unsolved topic.

Adult↗
PubMed1991

Freezing of cells--replacement of serum by oxypolygelatine.

A commercially available plasma expander (Gelifundol) containing 5.5% oxypolygelatine in buffered saline was used instead of serum as a supplement for freezing several types of human cell and a mouse myeloma cell line in liquid nitrogen. Viability, recovery, proliferation and cytotoxic activity were compared after freezing with a plasma expander and after conventional freezing with human AB serum or fetal calf serum. The plasma expander proved to be equivalent or superior to AB serum by all parameters tested and acceptable even when compared with fetal calf serum. Furthermore, this preparation is cheap, sterile, free of BSE, viral and mycoplasmal contamination or antibodies and foreign serum proteins. We therefore recommend it for freezing of cells for culture of HLA typing.

Animals↗