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F Mattner

Publications and source records attributed to F Mattner.

25 records · Page 2Linked to original sources
PubMed1996

Radiosynthesis of [123I]N-methyl-4-iododexetimide and [123I]N-methyl-4-iodolevetimide: in vitro and in vivo characterisation of binding to muscarinic receptors in the rat heart.

[123I]N-methyl-4-iododexetimide, [123I]MIDEX, and its pharmacologically inactive enantiomer [123I]N-methyl-4-iodolevetimide, [123I]MILEV were prepared via electrophilic iododesilylation using Chloramine-T as oxidising agent followed by N-methylation using methyl iodide. The radiotracers were purified with semi-preparative HPLC with radiochemical yields of 80 +/- 11% (n = 6). The average time of synthesis was 100 min with specific activity > 2000 Ci/mmol. In vitro, the binding of [123I]MIDEX, after addition of carrier, measured on homogenates of rat atrium was Bmax = 4.5 +/- 0.4 pmol/mg protein, Kd = 3.3 +/- 0.2 nM while in the ventricle Bmax = 2.3 +/- 0.2 pmol/mg protein, Kd = 4.0 +/- 1.4 nM. In vitro, the binding of [123I]MILEV was non-specific. The in vivo biodistribution of [123I]MIDEX showed high uptake in the atrium (3.2% ID/g) and left and right ventricles (2.2, 2.5% ID/g respectively) at 5 min followed by clearance. High heart-to-lung and moderate liver-to-lung ratios were obtained during 60 min. Radioactivity in the atrium and ventricles was reduced by pre-administration of the m-AChR antagonist MQNB (1 mg/kg). Pretreatment of rats with other m-AChR ligands, pirenzapine (M1), methoctramine (M2) and 4-DAMP (M3) also resulted in reduction of [123I]MIDEX uptake with methoctramine being the most potent. [123I]MIDEX distribution in the rat heart was not significantly inhibited by pre-administration of selective adrenergic drugs. The uptake was highly stereoselective since the inactive enantiomer, [123I]MILEV, demonstrated very low myocardial retention. The stability of [123I]MIDEX was evaluated by performing a metabolite study on atrium samples which revealed unchanged radiotracer 60 min postinjection. These results suggest that [123I]MIDEX may be a useful single photon agent for in vivo imaging of myocardial m-AChR in humans with [123I]MILEV offering the potential of assessing non-specific binding of the active tracer.

Animals↗
PubMed1993

Interleukin-12/T cell stimulating factor, a cytokine with multiple effects on T helper type 1 (Th1) but not on Th2 cells.

At least two subsets of CD4+ T helper cell lymphocytes termed Th1 and Th2 exist in the mouse and probably in humans. They are characterized by the secretion of different lymphokines and by their functional behavior. Dysregulated expansion of one or the other subset may be one reason for the development of certain diseases. Thus, it is of importance to define the signals involved in the differentiation and activation of the two Th cell subsets. It is known and has been confirmed in this report that the cytokine interleukin (IL)-1 acts on Th2 cells but not on Th1 cells. We now report that a previously identified cytokine which was provisionally termed T cell stimulating factor is identical with IL-12 and exhibits a reciprocal behaviour to IL-1. IL-12 has several effects on Th1 cells. It can induce the proliferation of certain Th1 cells in combination with IL-2. Synthesis of interferon (IFN)-gamma by Th1 cells can be triggered by IL-2 plus IL-12. In contrast to the IFN-gamma production observed after T cell receptor (TcR) CD3 stimulation of Th1 cells with lectin Concanavalin A the IFN-gamma production induced by IL-12 + IL-2 is insensitive to the immunosuppressive drug cyclosporin A. Furthermore, IL-12 enhances the TcR/CD3-induced synthesis of IFN-gamma of several Th1 clones. Finally, IL-12 (+IL-2) induces homotypic cell aggregation of Th1 clones. This type of cell aggregation depends on the participation of LFA-1 and ICAM-1 molecules. In all activation systems with Th1 cells no effect of IL-1 was demonstrable. In contrast, only IL-1 but not IL-12 served as a co-stimulatory signal for several Th2 cell lines activated via the TcR/CD3 complex.

Animals↗
PubMed1993

The interleukin-12 subunit p40 specifically inhibits effects of the interleukin-12 heterodimer.

The recently discovered cytokine interleukin (IL)-12 is a heterodimeric protein of two disulfide-bonded subunits of 35 and 40 kDa. IL-12 has multiple effects on T cells and natural killer (NK) cells. In particular it appears to be a major factor for the development of cellular immunity. So far activity of the single subunits alone has not been described, however their expression is regulated independently. In this report we demonstrate for the first time that the mouse IL-12 subunit p40 (IL-12p40) specifically antagonizes the effects of the IL-12 heterodimer in different assay systems. The proliferation of mouse splenocytes activated by phorbol ester and IL-12 was inhibited by IL-12p40, whereas the proliferation induced by phorbol ester and IL-2 was not affected. Furthermore, the synthesis of interferon (IFN)-gamma by mouse splenocytes activated with IL-2 and IL-12 was suppressed by IL-12p40. Purified mouse splenic CD4+ T cells produced IFN-gamma upon activation with plate-bound anti-CD3 monoclonal antibody which was enhanced more than tenfold in the presence of IL-12. In this system IL-12p40 inhibited only the enhancement caused by IL-12 but not IFN-gamma synthesis of CD4+ T cells stimulated with anti-CD3 alone. Moreover, IL-12p40 inhibited the effects of IL-12 on differentiated T helper type 1 (Th1) cells. IFN-gamma production by Th1 cells induced in a T cell receptor-independent way by macrophages and IL-2 or macrophages and IL-12 was greatly reduced by IL-12p40 providing evidence for the endogenous synthesis of IL-12 in the Th1 cell, macrophage and IL-2 co-cultures. The specificity of inhibition was clearly demonstrated in the homotypic aggregation assay of Th1 cells. Incubation of Th1 cells with either IL-2 and IL-12 or IL-2 and tumor necrosis factor induces LFA-1/ICAM-1-dependent aggregation. Only IL-2 + IL-12 but not IL-2 + tumor necrosis factor-induced aggregation was inhibited in a dose-dependent manner by IL-12p40. Thus, the IL-12 subunit p40 appears to be a specific inhibitor for the IL-12 heterodimer.

Animals↗
PubMed1993

The I-Ab-restricted alloresponse of D10.G4.1 T cells is based on the recognition of an endogenous peptide.

The alloreactivity of T cells is thought to be based on the cross-reactive recognition of allogeneic major histocompatibility complex (MHC) molecules which have bound peptides derived from self antigens or, in the case of cultured T cells, from serum components. While studying the processing requirements of conalbumin (CA) that is recognized by D10.G4.1 T cells in combination with I-Ak molecules we also analysed the cross-reactive stimulation of clone D10.G4.1 T cells by allogeneic, I-Ab expressing stimulator cells which is shown here to be CD4 dependent. In order to distinguish between an endogenous or exogenous origin of a peptide that is presumably co-recognized with I-Ab different types of stimulatory/antigen-presenting cells (APC) were treated with drugs that are known to influence the processing and/or presentation of antigens. It was found that the alloreactive response of D10.G4.1 cells was abolished if the APC were treated with brefeldin A or inhibitors of protein biosynthesis. Under the same conditions neither the CA-specific response of D10.G4.1 cells nor the activation of control T cells by ovalbumin (OVA) or insulin was affected. On the other hand, the use of lysosomotropic agents or inhibitors of glycoprotein trimming had no influence on the ability of the APC to induce the alloresponse of D10.G4.1 cells, whilst the presentation of CA and other protein antigens by the APC was prevented. In addition, treatment of APC with pronase to remove surface MHC molecules or acidic buffer to remove peptides from the binding groove of MHC class II molecules at the surface of APC strongly diminished their ability to induce an alloresponse. However, this capacity was restored by incubating the APC for 2 hr in serum-free medium. These data indicate that the alloreactive response of D10.G4.1 cells is based on the recognition of newly synthesized endogenous peptide(s) in combination with I-Ab.

Acids↗
PubMed1992

Different accessory function for TH1 cells of bone marrow derived macrophages cultured in granulocyte macrophage colony stimulating factor or macrophage colony stimulating factor.

The ability of macrophages to stimulate immune responses is heterogeneous and may have influence on the type of the developing immune response. Therefore, in an attempt to define different functional states of mouse macrophages, we made use of the two macrophage growth factors: macrophage colony stimulating factor (M-CSF) and granulocyte macrophage colony stimulating factor (GM-CSF). Generation of macrophages from freshly isolated bone marrow cells in the presence of GM-CSF results in a population expressing profound antigen presenting function for mouse TH1 cells, resulting in strong lymphokine production and proliferation of the T cells. Furthermore, high amounts of a novel soluble cytokine active on mouse TH1 cells are generated during the interaction of TH1 cells with macrophages elicited with GM-CSF. In contrast, macrophages grown from bone marrow cells for at least 14 days in the presence of M-CSF express only minimal antigen-presenting function for TH1 cells. Treatment of such macrophages for 24 h with either IFN-gamma or GM-CSF allows the distinction between two further functional states. Those treated with IFN-gamma efficiently presented antigen towards TH1 cells. The T cells produced large amounts of lymphokines and proliferate well. However, synthesis of the novel soluble cytokine (active on TH1 cells) was not detectable. The generation of this mediator requires a short-term treatment with GM-CSF of macrophages developed in the presence of M-CSF prior to their interaction with TH1 cells.

Animals↗
PubMed1991

Components of an antigen-/T cell receptor-independent pathway of lymphokine production.

The general way to induce the synthesis of lymphokines by T cells is the stimulation through the T cell receptor (TcR) complex which results in an increase of intracellular [Ca2+] and in the activation of a tyrosine kinase as well as of protein kinase C. Lymphokine production induced via the TcR is inhibited by the immunosuppressive drug cyclosporin A (CsA). However, an alternative pathway of lymphokine production exists. Several T lymphocyte clones can synthesize interferon-gamma (IFN-gamma), granulocyte-monocyte colony-stimulating factor, and small amounts of interleukin (IL3) when stimulated with syngeneic or allogeneic accessory cells (AC) plus IL2. In contrast to the TcR pathway the alternative pathway does not require a rise of intracellular [Ca2+] and is insensitive to the effects of CsA. In this report we provide evidence for the involvement of T cell-stimulating factor (TSF)--a probably novel murine cytokine--in the alternative pathway of lymphokine production. It is shown that fixation of the AC with carbodiimide or treatment of the AC with UV light greatly reduces their capacity to induce (in combination with IL2) the synthesis of IFN-gamma by T cells. This function is restored by addition of TSF. Moreover, TSF alone (without IL2) in combination with fixed AC can induce the synthesis of substantial amounts of IFN-gamma. Furthermore, TSF in combination with IL2 can stimulate freshly isolated spleen cells to produce IFN-gamma. The target cell resides probably in the non-B cell, non-T cell population.

Antigen-Presenting Cells↗