Search PubMed⌕ Search

Biomedical subjects

W Müller-Ruchholtz

Publications and source records attributed to W Müller-Ruchholtz.

At least 73 records · Page 4Linked to original sources
PubMed1993

The influence of graft-versus-host reactivity, lymphocyte depletion, and cell dose on allogeneic bone marrow engraftment.

Graft rejection has hampered the use of T cell depletion (TCD) in allogeneic bone marrow transplantation. A model of host-versus-graft (HVGR) and graft-versus-host reaction (GVHR) as two inversely related processes has been proposed. We investigated graft rejection rates in graft-versus-host-reactive and graft-versus-host-nonreactive situations in a rat and a mouse model. Model 1: LEW rats were pretreated with a fixed myeloablative dose of busulfan and increasing doses of the immunosuppressive cyclophosphamide. The animals received different doses of semiallogeneic GvH-nonreactive BM cells. Graft rejection rates were dependent on the bone marrow cell number transplanted and on the pretransplant immunosuppression. Graft rejection rates following transplantation of GvH-reactive CAP marrow and genetically GvH-nonreactive (CAP x LEW)F1 marrow were the same. In conclusion, there was no advantage with respect to engraftment for the GvH-reactive marrow. Model 2: In irradiated Balb/c mice, graft rejection rates following T cell-depleted and unmanipulated transplantation of GvH-reactive or GvH-nonreactive bone marrow grafts were identical. All experiments were done with graded numbers of BM cells and revealed a strong impact of the BM cell dose on engraftment. In our experiments the cell loss during the ex-vivo manipulation was approximately 50% and, in contrast to the clinical situation, we readjusted to the intended number after TCD. Our experiments demonstrate that neither GvHR nor T cells but the BM cell dose has a strong impact on engraftment of allogeneic bone marrow.

Animals↗
PubMed1993

Natural killer cells as effector cells of graft-versus-leukemia activity in a murine transplantation model.

The transfer of cytotoxic effector cells reduces the risk of relapse after allogeneic BMT. Two murine leukemia cell lines, A20 (B lymphocytic) and WEHI-3 (myelomonocytic), were used to investigate antileukemic effector mechanisms operating independently from graft-versus-host disease (GVHD). Different results were obtained with the two leukemia models. After injection of A20 cells, the majority of Balb/c recipients treated with syngeneic BMT died due to leukemia relapse (89%). The transplantation of MHC-matched DBA marrow resulted in chronic GvHD but did not reduce the risk of relapse (86%). Grafting of MHC-mismatched (but GvH-nonreactive) marrow cells from (C57xBalb)F1 hybrids, however, led to a significantly lower relapse rate (47%, p < 0.05). In vitro testing revealed that F1 cells but not Balb/c or DBA cells exert NK cell activity against A20. The elimination of NK 1.1-positive cells from the graft reduced the antileukemic activity of (C57xBalb)F1 marrow against A20 in vivo. After injection of WEHI-3 leukemia cells, syngeneic BMT cured most of the recipients (62%) and transplantation of (C57xBalb)F1 marrow provided no additional benefit. In contrast to unmanipulated Balb/c and (C57xBalb)F1 cells, which showed no NK activity against WEHI-3 in vitro, IL-2 treated effector cells were highly cytotoxic. Transfer of IL-2 preincubated grafts significantly decreased the relapse rate of WEHI-3 (19 vs. 38%) after syngeneic and allogeneic BMT. Our data indicate that GvL activity can be separated from GvHD. In our murine model, GvL activity appears to depend more on the donors NK/LAK cell activity than on the presence or absence of GvHD.

Animals↗
PubMed1993

Hematological effects of the new immunosuppressive drug 15-deoxyspergualin.

Since systematic hematological studies on blood and bone marrow changes after treatment with 15-Deoxyspergualin (DOS) are lacking, a quantitative assessment was performed fourteen or twenty eight days after intraperitoneal application of DOS to rats. Further observations done 7 and 14 days after discontinuation of DOS administration allowed analysis of bone marrow regeneration. DOS induced lymphocytopenia, granulocytopenia and anemia with a decrease of bone marrow cellularity due to suppression of cell maturation. The effect was dose-dependent and bone marrow as well as blood changes were observed in animals treated with doses from 0.5 to 10.0 mg/kg DOS. Within 14 days after termination of the treatment, rapid recovery with normalization of all hematological parameters was observed. In the light of our data, these hematological side effects may not be a major disadvantage, if DOS is used in doses below 2.5 mg/kg, and for a course of therapy which is limited to 7 to 14 days.

Animals↗
PubMed1993

[HLA typing in high risk keratoplasty].

UNLABELLED: Improved microsurgical techniques and better immunosuppressive treatment have led to an increase in the number of corneal transplantations. However, graft rejection due to a disparity between donor and recipient major histocompatibility antigens remains the major complication. The risk of graft rejection is further increased in patients with vascularized graft beds and in presensitized persons. Well-designed experimental studies and clinical experience have clearly shown the importance of class-I-antigens. However, class-II antigens have not yet been studied to the same extent. METHODS: Multiorgan donors and corneal graft recipients were HLA typed using the lymphocytotoxicity test previously described by Terasaki. The recipients were typed retrospectively. Cadaver corneal graft donors were typed using a novel HLA typing technique on retinal pigment epithelial cells, as previously described by us. Postoperatively, all recipients were routinely examined for rejection over a period of 2 years. RESULTS: Graft rejection was observed in 25% of the 133 high-risk patients. Of the 13 class-I-typed patients who showed a rejection 9 persons had two or more major histocompatibility mismatches. Of the 12 patients without rejection problems only 5 had two or more HLA class-I-mismatches. Of the patients with one or two matches at the HLA-DR locus there were only 4 out of 9 patients with at least one graft rejection; 5 out of 6 patients showed no signs of rejection. CONCLUSIONS: Mismatches at either class-I- or class-II- gene loci lead to a higher frequency in corneal graft rejection. Apart from the major histocompatibility mismatches, other factors also influence graft rejection, such as the distance between the corneal transplant and corneal vessels, presensitization, and the indication for corneal grafting. If we are to define the factors influencing graft rejection better and further increase our knowledge on the role the major histocompatibility antigens play in corneal graft rejection in a larger patient group, then cooperation with other transplantation centers will be required.

Graft Rejection↗
PubMed1992

New parental cell lines for generating human hybridomas.

In contrast to the success achieved with the production of hybridomas in the mouse system, creating human hybridomas is problematic. The reason is believed to be a lack of suitable malignant human cell lines. The work presented here demonstrates the establishment of three human parent cell lines--two of which are of T cell origin--by installing hypoxanthine guanosine phosphoribosyl transferase (HGPRT) and/or thimidine kinase (TK) deficiencies into the leukemic cell lines REH, 1301 and SKW-3. In order to isolate true hybridomas, selection procedures must guarantee complete death of the enzyme-deficient malignant parent cells. In this respect sublines with a combined HGPRT and TK deficiency proved to be superior to those with only one enzyme deficiency, especially in combination with the newly developed hypoxanthine/aminopterine/thymidine/azaserine (HATA) selection medium. However, selection media should be of low nonspecific toxicity. This was shown to be a particular property of the thymidine-free azaserine/hypoxanthine (AH) selection medium. Preliminary data show an extraordinary ability of one subclone of the hypoxanthine guanosine phosphoribosyl transferase-negative T cell line SKW-3 to generate human T-T hybridomas. They are of a stable, nearly tetraploid karyotype and express new surface antigens, thus providing new possibilities for the investigation of human T lymphocyte function by means of hybridoma technology.

Cell Line↗
PubMed1992

Specific down-regulation of allograft reactivity at the cellular level: graft cells and responder T cells.

Local immune reactivity in an allograft is largely determined by (1) the immunogenicity of the grafted cells and (2) the presence of recipient allospecific T lymphocytes and, much more importantly, their capacity to react and initiate damage to the graft. Ad (1): It is still widely believed that allograft immunogenicity is sufficiently described by the cell surface expression of transplantation antigens, in particular MHC class I and II molecules. In extension of earlier, more complex models it will be demonstrated that transfected subclones of a macrophage cell line show unaltered, strong MHC expression but have become non-immunogenic and, most importantly, have acquired the capacity to render mature naive T cells anergic in a specific fashion. Ad (2): Starting from the above and from other observations, we have found in human organ graft recipients that cytotoxic T lymphocyte (CTL) frequencies may be specifically down-regulated but may regain their reactivity after cultivation under ex vivo conditions. In keeping with the latter we can now show quantitatively the variable presence and the functional potential of cell-released (soluble) human MHC (HLA class I) molecules: they are able to specifically inhibit human CTL reactivity in a dose-dependent fashion. Taken together, it may be concluded that studies at the cellular level, in particular the level of human cells, will increasingly help us to better understand and manipulate the immunological interplay between the local graft cell and its most important antagonist, the T lymphocyte.

Animals↗
PubMed1992

Post-mortem HLA tissue typing of retinal pigment epithelial cells.

Retinal pigment epithelial cells (RPE) were derived from bulbi of cornea donors and maintained in culture. The time-span between donor's death and cell cultivation ranged from 2 to 122 h. The mean numbers of hours was 25.6 (n = 130). After IFN-gamma stimulation, cells were serologically typed for class I and class II antigens. Unclear class I allospecificities were verified by one-dimensional isoelectric focusing. Data from the serological typing of lymphocytes and those of the serological and biochemical typing of RPE from the same donors were compared in 22 cases. There was a discrepancy of less than 5%, whereby either the typing on lymphocytes could not identify some specificities declared as blanks or the RPE typing had failed to clearly define a specificity. Our data show that the strategy adopted here is very successful for tissue typing post mortem, thus increasing the number of available HLA-matched corneas and consequently reducing the number of corneal graft rejections.

Adolescent↗
PubMed1992

Tissue distribution of MHC class II--positive cells, their down-manipulation by monoclonal antibodies and potential role in organ allograft immunogenicity.

This review article presents current state of knowledge of tissue distribution of MHC class II antigens in rat kidney. Our attention focuses particularly on down manipulation of these antigens by monoclonal antibodies. The results of organ perfusion procedure on prolongation of graft survival and perspectives of further studies are also discussed.

Animals↗
PubMed1992

[Characteristics of changes of personal odor after experimental bone marrow transplantation].

In an operant conditioning paradigm 4 Balb/c inbred strain mice were conditioned to discriminate between urine samples of two other inbred strains. The purpose was to examine whether or not the known stimulus configuration during training had any effect upon the rate of recognition of other stimuli. On the basis of this procedure, we subsequently investigated the extent to which an allogeneic bone marrow transplantation interferes with the olfactory identity of an individual. For the transplants a strain was inbred which had no contact to the animals tested, a procedure used for the first time here. Furthermore, also for the first time, it was possible to demonstrate in a direct comparison, the role played by donor versus recipient characteristics on the olfactory composition of the recipients odor.

Animals↗
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↗