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S Thierfelder

Publications and source records attributed to S Thierfelder.

At least 73 records · Page 4Linked to original sources
PubMed1990

Antigen density on target cells determines the immunosuppressive potential of rat IgG2b monoclonal antibodies.

The current studies were designed to determine the relevance of T cell antigen density, besides antibody isotype, with regard to the success of antibody serotherapy. We compared the immunosuppressive effects of two rat IgG2b monoclonal anti-Thy-1 antibodies, RmT1 and 30-H12, with distinct binding sites in a graft-vs.-host disease (GVHD) model of fully H-2 and I-A region-mismatched bone marrow transplantation, making use of the difference in Thy-1.2 antigen density between homozygous (BALB/c) and heterozygous (BALB/c X AKR/J)F1 GVHD-promoting donor cells. Antibodies RmT1 (directed against a monomorphic determinant on mouse Thy-1) and 30-H12 (reactive with the Thy-1.2 allele-specific determinant) did not differ in their anti-GVHD activity with regard to Thy-1.2 homozygous grafts. However, in the region of a critical number of binding sites a small difference in the amounts of the two antibodies bound (about 8 X 10(3) IgG molecules/cell) obviously accounts for a great difference in anti-GVHD activity. This is shown in a two haplotype host-graft disparity between C57BL/6 recipients treated with either RmT1 or 30-H12 before challenging them with (BALB/c X AKR/J)F1 grafts, where the Thy-1.2 antigen concentration is approximately 50% compared to the density on BALB/c lymphocytes. Here, mAb 30-H12 loses its remarkable in vivo immunosuppressive quality, whereas RmT1 treatment protects mice against lethal GVHD. Binding sites were quantitated using a computerized approach for the analysis of data from ligand binding experiments of the respective mAb, RmT1 and 30-H12, coated to LN cells of BALB/c and F1 hybrid origin. Furthermore, the in vivo immunosuppressive activity of rat IgG2b antibodies directed against Thy-1 was found to correlate with their ability to generate stable antibody-C1q complexes on the cell surface of immunocompetent T cells.

Animals↗
PubMed1990

Dose rate and fractionation of total body irradiation in dogs: short and long term effects.

Variations of regimens of total body irradiation (TBI) were investigated in the dog as a preclinical model for bone marrow transplantation. Inactivation of hemopoietic precursor cells (CFU-GM) was studied following irradiation of marrow in vitro, following TBI at sublethal doses in vivo and following autologous transplantation of marrow obtained after sublethal TBI. Inactivation and recovery of CFU-GM as well as restoration of hemopoiesis following autologous transplantation was independent of the dose rate, but nadirs of blood counts were lower following sublethal TBI with the higher dose rate. Acute non-hemopoietic toxicity of TBI depended on the dose, the dose rate and the total treatment time and not on the fractionation regimen. At a total dose of 25 Gy acute mortality was prevented by prophylactic administration of oral, non-absorbable antibiotics. Late mortality was due to degenerative and autoimmune-like disorders with or without infections and to malignant tumors. Evaluation of long-term survival is still preliminary, since surviving dogs of two groups (10 Gy as single dose, 25 Gy as hyperfractionated TBI) have not yet reached the median survival time of their group. So far, long-term survival depended on the total dose (p = 0.05) and, possibly, the fractionation regimen (p = 0.12). The latency period until development of malignant tumors was influenced by the total doses given in the same treatment time (p = 0.05) and by the total treatment time for equal doses (p = 0.04). It was concluded that TBI at a low dose rate may give the best therapeutic ratio of inactivation of hemopoietic precursor cells to acute toxicity.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Monoclonal antibodies to complement components without the need of their prior purification. II. Antibodies to mouse C3 and C4.

Rat monoclonal antibodies (MAbs) to mouse complement components C3 and C4 were produced by immunizing rats with cell-bound C3 and C4. This principle involves: a) using mouse thymocytes coated with syngeneic rat antibody isotypes that show high affinity to C1q, b) the intercalation of C1q from serum and c) the subsequent activation of the classical complement pathway leading to deposition of cell-bound complement components. Screening for anti-complement antibodies was performed on antibody coating microtiter plates with mouse serum as source of complement. The reactivity of the MAbs was determined by variations of the ELISA screening system using EDTA-serum to inhibit complement activation by C1 dissociation, serum rendered deficient of functionally active C3 by treatment with cobra venom factor (CVF) or serum of genetically C5-deficient mice. The specificity of the MAbs was confirmed by affinity chromatography followed by SDS-PAGE and immunoblotting. We were able to establish a panel of anti-C3 and anti-C4 MAbs of various isotypes.

Animals↗
PubMed1990

Antilymphocytic antibodies and bone marrow transplantation. XI. Evidence that reduced Thy-1 expression in Thy-1.1 mice prevents suppression of graft-versus-host disease with anti-Thy-1 monoclonal antibodies.

Considerable variations in the suppression of graft-versus-host disease with monoclonal anti-Thy-1 antibodies were found to relate to substantial differences noted in the expression of mouse Thy-1 marker on lymph node and spleen cells of Thy-1.1 (AKR/J, C57BL/6.Thy-1.1) and Thy 1.2 (AKR/Cu, C57BL/6) mice. Thy-1.1 mice showed a population of 22% (AKR/J) or 13% (C57BL/6-Thy-1.1) of Thy-1 negative cells among peripheral T cells carrying Ly-1 marker. This was in sharp contrast with Thy-1.2 mice, where as expected practically all peripheral T cells expressed both Thy-1 and Ly-1. Double-marker analysis on FACScan revealed that the Thy-1-/Ly-1+ cell population identified in Thy-1.1 but not in Thy-1.2 mice doubtless represents T cells because they express CD3 and either the L3T4 (CD4) or Lyt2 (CD8) phenotype. Using quantitative fluorescence-measurement techniques, it was found in addition that the Thy-1 antigen-binding sites on Thy-1+ cells from Thy-1.1 mice are considerably fewer than those present in Thy-1.2 mice. In fact, the Thy-1 antigen-binding sites approximate the level of Ly-1 density. Consequences of the reduced expression of Thy-1 became apparent in vivo: (1) lymphnode and splenic T cell areas in Thy-1.1 mice were clearly less depleted when Thy-1.1 and Thy-1.2 mice had been injected with rat IgG2b anti-Thy-1 mAb; and (2) GvHD was prevented completely in fully mismatched mice by anti-Thy-1 mAb if the donor mice expressed Thy-1.2 but was barely delayed if the donors expressed Thy-1.1. Thus the present study provides a transplantation model for comparing differences in T antigen density and their consequences for antibody-induced immunosuppression.

Animals↗
PubMed1990

[Experimental studies of the so-called emulsification behavior of silicone oil: effect of viscosity].

The stability of intraocularly applied silicone oils plays an important role in their biocompatibility. The clinically used silicone oils are not a unique group of materials. There are important differences regarding viscosity and the amount of low molecular and ionic components. A sign of bioinstability of silicone oils is silicone oil emulsification. According to clinical experience and experimental studies, less viscous silicone oils seem to emulsify earlier then more viscous oils. Therefore, we investigated three highly purified polydimethylsiloxanes with defined physicochemical characteristics and viscosities of 1,000 cs, 5,000 cs and 10,000 cs for their in vitro stability. As detergents, we used fibrin, fibrinogen, gammaglobulins, acidic alpha-1-glycoprotein, very-low-density lipoprotein (VLDL), and serum. The oil with a viscosity of 1000 cs was the most unstable silicone oil whereas the oils of 5,000 cs and 10,000 cs reacted similarly. The most effective detergents were fibrin, fibrinogen and serum-causing emulsification for all silicone oils investigated whereas gamma-globulins, acidic alpha-1-glycoprotein and VLDL only emulsified the less viscous oil of 1,000 cs. Our results show the importance of viscosity for the stability of silicone oils and the effect of biologically potential detergents.

Drug Stability↗
PubMed1989

Immunocytochemical identification of meningeal leukemia and lymphoma: poly-L-lysine-coated slides permit multimarker analysis even with minute cerebrospinal fluid cell specimens.

Use of immunocytology for accurate identification of malignant cells in cerebrospinal fluid (CSF) has so far been hampered by high cell requirements of the immunologic methods hitherto used. In an attempt to minimize cell loss in cytopreparation, electrostatic binding of cells to poly-L-lysine (PLL)-coated multispot slides, followed by immunocytochemistry, was investigated. Using optimized conditions of cell attachment and fixation and performing all washing procedures on the slide made multimarker analysis possible even in paucicellular specimens, while preserving excellent cell morphology and yielding high sensitivity in the detection of antigens. In a study of 26 CSF specimens with inconclusive cytomorphology, comprising 335 single marker determinations, we were able to discriminate reliably between resting or activated benign cells and a wide range of types of malignant lymphoid cell. A definitive diagnosis was reached in all cases by one tap only. Malignant meningitis was ruled out in ten specimens and proved in 16, including five in which the type of malignancy could only be determined by immunophenotyping. We conclude that immunocytochemistry on PLL-coated slides constitutes the method of choice for immunologic cell differentiation in CSF, which allows equivocal morphologic findings to be clarified.

Adult↗
PubMed1989

Distribution of injected anti-Thy-1 monoclonal antibodies in mouse lymphatic organs: evidence for penetration of the cortical blood-thymus barrier, and for intravascular antibody-binding onto lymphocytes.

The localization of monoclonal anti-Thy-1 binding in mouse thymus, spleen, and lymph nodes was studied at early intervals after intravenous (i.v.), intraperitoneal (i.p.) and subcutaneous (s.c.) injection of a single dose of the monoclonal antibody (MAb). Five minutes after i.v. injection, anti-Thy-1 was bound to cortical thymocytes surrounding capillaries in the thymic cortex, to thymic cells beneath the thymic capsule and to medullary thymocytes around venules of the thymus medulla. When anti-Thy-1 was injected i.p. or s.c. the MAb was first deposited in capillary walls in the thymus cortex and did not appear on thymocytes outside of capillaries until 60 min after injection. These findings suggest that thymic cortical capillaries are permeable for anti-Thy-1 MAb contrary to the generally accepted principle of a blood thymus barrier to antigens in thymic cortex. Some cortex capillaries also became permeable for peroxidase when injected 15 min after anti-Thy-1 MAb. Anti-Thy-1 MAb penetration into spleen white pulp and lymph node paracortex occurs along the circulatory pathway of the vascular system in the spleen and of lymphatics in lymph nodes. But those lymphocytes with a strong anti-Thy-1 MAb loading always appeared along the pathways of lymphocyte circulation indicating that the most intense contact between anti-Thy-1 MAb and T-lymphocytes occurs not in the lymphatic organs but during the intravascular period of recirculation of lymphocytes.

Animals↗
PubMed1989

Monoclonal antibodies to complement components without the need of their prior purification. I. Antibodies to mouse C1q.

Rat monoclonal antibodies (MAbs) reactive with mouse complement subcomponent C1q were raised applying a principle that requires minute amounts of serum and circumvents purification of serum-derived C1q. The principle involves a) using the high affinity of certain cell-bound antibody isotypes for intercalating C1q from serum of various species, b) selecting such antibodies as are syngeneic to the immunized animal species, thus avoiding the production of antibodies against the intercalating antibodies and c) screening for the anti-C1q MAb in microtiter plates coated with C1q-intercalating MAb isotypes that are heterogeneic to the immunized animal species. We could establish 3 MAbs of IgM subclass, whose reactivity to mouse C1q was shown by ELISA techniques. One of them (RmC13C9) crossreacted with human C1q and was shown by SDS-PAGE and subsequent immunoblotting to recognize the C-chain of mouse and human C1q. The other two MAbs are directed against SDS-sensitive epitopes on mouse C1q and were, therefore, further characterized by native agarose gel electrophoresis and immunohistochemical studies.

Animals↗
PubMed1989

Neutralization of immunosuppression by antibodies against variable as well as constant regions of monoclonal anti-Thy-1 xenoantibodies and their ability to be suppressed by initial T cell depletion.

Timing, magnitude, and effect of the murine antibody response to rat pan-T-cell antibodies were studied in a bone marrow (C57BL/6-to-CBA mice) transplantation model. Prospective C57BL/6 marrow donor mice were sensitized against pan-T-cell (Thy-1, Thy-1.2, Lyt-1) monoclonal antibodies of various rat isotypes or against polyclonal rat antimouse-thymocytes (rat ATG) antibodies. Three days prior to transfer of spleen and bone marrow cells, the sensitized C57BL/6 donors received a dose of anti-Thy-1 mAb (RmT1) known to abolish graft-versus-host reactivity of unsensitized donors. The injected mAb provoked anti-antibodies reacting with RmT1. The anti-antibodies inhibited immunosuppression of the rat mAb RmT1 even if they bound only to nonidiotypic epitopes on RmT1. Avoiding cell-binding of the sensitizing rat anti-Thy-1.2 mAb by its injection into Thy-1.1 mice induced only low-titer and delayed anti-antibodies. This indicated the enhanced immunization potential of anti-Thy-1 when bound to cells. Finally, sensitization leading to the mouse antirat anti-antibodies and reversion of immunosuppression was prevented or reduced considerably by T cell depletion with a mouse IgG2a anti-Thy-1.2 mAb or high-dose cyclophosphamide or by rabbit ATG, provided it was initiated before starting the sensitizing injections of the rat antimouse T cell antibodies.

Animals↗
PubMed1989

Bone marrow transplantation for the treatment of leukaemia-results of the Munich Cooperative Group.

This report summarizes the results of marrow transplantation from HLA-identical siblings and syngeneic twins for treatment of acute myelogenous leukaemia, chronic myelogenous leukaemia, acute lymphoblastic and undifferentiated leukaemia from 1975 until December 1986. Three conditioning regimens and treatment of the marrow graft in vitro with absorbed antithymocyte globulin or the monoclonal antibody "Campath 1" for prophylaxis of graft-versus-host disease (GVHD) have been studied and analyzed retrospectively. The regimen of total body irradiation in large fractions of 4 Gy and of cyclosphosphamide (200 mg/kg) has achieved the most favorable results. Inactivation of T-cells by treatment of the marrow "in vitro" has decreased the severity of GVHD without improving survival. The antileukaemic effect of the graft may be important for control of the disease and may be improved by better immunosuppression of the recipient.

Adolescent↗
PubMed1989

Antilymphocytic antibodies and marrow transplantation. IX. T-cell depletion in marrow donors with C1q high and low affinity antibodies for suppression of GVHD in fully mismatched mice.

Rat monoclonal antibodies (mAbs) of the same specificity (anti-Thy-1) but different immunoglobulin (Ig) subclass were investigated for their effect on suppression of graft-versus-host disease (GVHD) by depleting the marrow donors of T cells in vivo. Transplantation to homozygous, fully mismatched mice of spleen and bone marrow cells from unthymectomized mice injected with the mAbs revealed that two rat anti-Thy-1 mAbs with high affinity for C1q (IgG2b) suppressed and prevented acute and chronic mortality of GVHD. In contrast, rat mAbs with low affinity for C1q (IgM, IgG2c) barely delayed acute mortality. This correlated with findings on the degree of splenic T-cell depletion in donor mice with the IgG2b mAb, able to deplete 97%, and the IgG2c and IgM mAbs, only 83% and 75% of T cells, respectively. An effect akin to the one achieved with IgG2b was seen, however, when donor mice were thymectomized and then treated with three injections of IgG2c isotype. The rat IgM mAb was not immunosuppressive even under such conditions. Immunocytochemical and immunohistochemical examination of the donor lymph nodes after single injection of either mAb showed that only 84% of T cells were eliminated, and in contrast to the spleen, none of the tested antibodies could deplete T cells further. The thymus did not appear depleted at all, although the cortical thymocytes were coated with either of the injected mAbs.

Animals↗
PubMed1988

Recognition of two epitopes of an antigen present on canine T cells but not on hemopoietic progenitors by four monoclonal antibodies.

Pairs of murine monoclonal antibodies, which recognize 2 different epitopes on a single antigen are described. These antibodies (MdT-P1, -P2, -Q1, -Q2) defining a canine pan-T cell antigen, were raised against dog thymocytes. In immunoblotting of solubilized and polyacrylamide gradient gel electrophoresis in sodium dodecyl sulphate (SDS-PAGE) fractionated dog thymocytes, they revealed a strong heterogeneous antigen. Competitive inhibition of binding of directly labeled mouse-antidog T lymphocytes monoclonal antibodies (MdT-mAbs) to solubilized dog thymocytes indicates that 2 different antigenic epitopes (P, Q) are recognized. In indirect peroxidase immunocytochemistry, MdT monoclonal antibodies recognized up to 95% thymocytes, 69% blood lymphocytes, 76% lymph node lymphocytes, and approximately 2% bone marrow lymphocytes; they were nonreactive with surface immunoglobulin positive blood cells, monocytes, platelets, cells of myelo- and erythropoietic lineage in the bone marrow. Immunohistochemistry on thymus, lymph nodes, and spleen sections revealed that MdT-mAbs had labeled cortical and medullary thymocytes, paracortical T cell areas in lymph nodes and the periarteriolar zone of spleen white pulp, whereas B cell areas remained unstained. The antibodies lysed dog thymocytes in the presence of complement. Lethally irradiated dog receiving bone marrow autograft depleted of MdT-P1 positive cells ex vivo showed engraftment and complete recovery of marrow function. Studies of antibody activity on canine hemopoietic progenitor cells in granulocyte-macrophage progenitors (CFUGM) also showed no reduction of CFUGM in MdT-P1-depleted bone marrow.

Animals↗
PubMed1987

In vivo immunosuppression by pan-T cell antibodies relates to their isotype and to their C1q uptake.

There is considerable interest in the use of monoclonal anti-T cell antibodies for immunosuppression during organ transplantation. However, the in vitro cytotoxic titers of these monoclonal reagents do not correlate with their immunosuppressive potency when injected in vivo. A relationship nevertheless seems to exist between immunosuppression and the isotype of anti-mouse Thy-1 antibodies, because among several anti-Thy-1 antibodies of mouse and rat origin, the only two found to cause immunosuppression in vivo belonged to the rat IgG2b and mouse IgG2a isotype. We show here that a quantitative positive correlation exists between an antibody-induced humoral effector mechanism and immunosuppression. We measured the uptake of the C1q complement subunit by polyclonal rabbit and rat anti-thymocyte globulin and also seven monoclonal anti-Thy-1 antibodies in an immunohistochemical assay or a radioimmunoassay. Immunosuppression was studied in a murine graft-vs-host and skin allograft model. Our results suggest strongly that a stable association between the C1 protein and a potential binding antibody is an essential prerequisite of antibody-dependent cell inhibition in vivo that suppresses the immunoresponse against strongly incompatible transplantation antigens.

Animals↗
PubMed1987

Biopterin synthesis in mouse spleen during bone marrow transplantation correlates with unimpaired hemopoietic engraftment.

Normal engraftment of bone marrow transplants depends on histocompatibility between donor and recipient. In this case reconstitution of hemopoiesis and lymphopoiesis in the mouse spleen is correlated with transient biopterin synthesis in these cells. Allogeneic bone marrow progeny cells undergo donor cell proliferation in the spleen prior to the incidence of graft-versus-host reaction. These cells are not committed to biopterin synthesis. Thy-1 monoclonal antibody fully repairs engraftment of allogeneic transplants together with biopterin synthesis.

Animals↗