Two distinct signals regulate induction of IL-2 responsiveness in CD8+ murine T cells

In the model system used here, cross-linking of T-cell receptor structures (TCR) by antigen-presenting cells (APCs) is substituted by the use of anti-F23.1 anti-T-cell receptor monoclonal antibody immobilized on Sepharose beads. We show that CR cross-linking of resting murine CD8+ T cells seeded at low cell densities is insufficient to induce responsiveness to the growth-promoting effect of interleukin-2 (IL-2), i.e. fails to induce expression of functional IL-2 receptors. The macrophage cell-line product, IL-2 receptor-inducing factor (RIF), but not IL-1, IL-3, IL-4 and interferon-gamma (IFN-gamma) functions efficiently as a co-stimulator. Once activated, growth of CD8+ T cells is driven entirely by IL-2. We conclude that two restriction points control the activation of resting CD8+ T cells. While cross-linking of TCR is essential as the first step, RIF is required as the competence factor to induce IL-2 responsiveness. We consider the possibility that the ability of APCs to produce RIF determines the immunogenicity of APCs towards antigen-reactive resting CD8+ T cells.

High-dose irradiated splenic stimulator cells show no endogenous interleukin-2 production but stimulate clonally developing helper T cells to produce interleukin-2

The effect of various physical or chemical treatments of splenic stimulator cells on their endogenous, mitogen-inducible IL-2 production and on their ability to induce IL-2 production in clonally developing helper T lymphocytes was investigated. While most methods (T cell depletion by monoclonal antibodies plus complement, glutaraldehyde fixation, heat inactivation and high-dose irradiation) effectively suppressed the endogenous IL-2 production of splenic stimulator cells, only T cell depletion and high-dose (6000-10,000 R) irradiation sustained their stimulatory capacity. High-dose irradiated stimulator cells induced high numbers of clonally developing helper T lymphocytes to secrete IL-2. Moreover, this induction was found to be antigen-specific. Hence, high-dose irradiation is a simple, rapid and reliable method for the treatment of stimulator cells, especially when large numbers of cultures are to be screened.

Androsta-4,16-diene-3,6-dione: an unknown member among the smelling androst-16-enes

The synthesis of a still-unknown member of the physiologically interesting 16-unsaturated C19 steroids - androsta-4,16-diene-3,6-dione - is described. The spectroscopic data of the new compound are reported.

Nachweis von Corticosteroiden im Fett von Dachs und Murmeltier / Detection of Corticosteroids in Fat of Badger and of Alp-Marmot

In our search for the antiinflammatory activ principles of fat of badger and alp-marmot, used in folk-medicine as remedies against rheumatism and arthritis, eight known corticosteroids have been detected and identified in the lipophilic fraction of body fats of both animals. Enrichment and detection succeeded by using TLC, straight phase HPLC with diode array equipment, HR-GC on OV-1 capillary columns and GC/MS of the methyloxime-trimethylsilylated steroids. The amount of the detected steroids ranges from 30-40 mg/kg. The whole antiinflammatory activity of the fat, as measured in the rat paw edema test, results from these and further hitherto unidentified cortico-steroids.

Wedelolactone and coumestan derivatives as new antihepatotoxic and antiphlogistic principles

For the study of structure-activity relationships, the antihepatotoxic wedelolactone (7-methoxy-5,11,12-trihydroxy-coumestan) and 6 coumestan derivatives were synthesized by the application of a modified method of Wanzlich. An evaluation of the biological characteristics of the synthetic compounds and acuminatin from Musa acuminata showed that most of the wedelolactone derivatives significantly protected primary cultured liver cells from the toxicity of CCl4, galactosamine (Galc), and phalloidin, and strongly inhibited the activity of 5-lipoxygenase in porcine leukocytes. The hepatocyte protective activity was dependent on the C-7 substitution with pharmacological efficacy decreasing in the following order: EtO greater than MeO greater than OH greater than CH3(CH2)9. In addition, a free OH at C-5 of the wedelolactone molecule was shown to be important in protecting hepatocytes from CCl4 and Galc damage. Similar observation regarding the effect of C-7 substitution in wedelolactone was obtained in the 5-lipoxygenase test. In general, an increase in the lipophilicity in ring A increased the inhibition of 5-lipoxygenase activity. The synthetic wedelolactone was also found to have stimulatory effect on the RNA synthesis in isolated nuclei from hepatocytes.

Interleukin 4 (BSF-1) induces growth in resting murine CD8 T cells triggered via cross-linking of T3 cell surface structures

To analyze the role of interleukin 4 (IL4, BSF-1) during primary activation of resting (high-density) murine CD8 T cells, a model system was used which bypasses antigen-presenting cells by the use of anti-T3 monoclonal antibodies immobilized on Sepharose beads. In high, but not in low cell density cultures, IL4 alone induced cell growth. In low cell density cultures, further to T3 cross-linking a soluble macrophage product was required as co-stimulator to induce sensitivity to IL4. This co-stimulator activity was unrelated to recombinant (r)IL1, rIL6 and rTNF-alpha (tumor necrosis factor alpha). In primary CD8 T cell responses rIL4-driven growth was about half of that induced by rIL2, and not inhibitable by anti-IL2 receptor antibodies. Higher concentrations of IL4 down-regulated cell proliferation. In the course of IL4-driven growth, the proliferating cells acquired sensitivity to the growth-promoting effect of IL2. Activated CD4 or CD8 T cells were found to be equally sensitive to the IL4 and IL2-driven growth pathway. Taken together, these results define a physiologic role of IL4 as growth factor during primary activation of resting CD8 T cells and thus extend the spectrum of target cells for IL4.

New Chlorine-Containing Sesquiterpene Lactones from Chrysanthemum parthenium

From the leaves of CHRYSANTHEMUM PARTHENIUM (L.) Bernh. (feverfew) two new chlorine-containing sesquiterpene lactones were isolated and structurally elucidated, mainly by NMR spectroscopy and X-ray analysis.

Reactivity of Ly-2+ T cells against 2,4,6-trinitrophenyl (TNP)-modified syngeneic stimulator cells: specificity, frequency of interleukin 2-producing Ly-2+ helper T cells and clonal segregation from Ly-2+ cytotoxic T lymphocytes

The in vitro reactivity of purified murine Ly-2+ and L3T4+ T cells towards 2,4,6-trinitrophenyl (TNP)-modified syngeneic stimulator cells was analyzed. Both T cell subpopulations autonomously proliferated and produced interleukin 2. In either the Ly-2+ or L3T4+ T cell subset the frequencies of TNP-specific interleukin 2 (IL 2)-producing T lymphocyte precursors (IL 2 TL-p) were equally high (f = 1/400-1/1000). Clonally developing IL 2 TL of either T cell subset showed an exquisite antigen (TNP) specificity as shown by the split culture approach. TNP-specific Ly-2+ IL-2 TL used class I MHC (H-2Kk) gene products as major histocompatibility complex (MHC) restriction elements, while L3T4+ IL 2 TL proved to be class II MHC (H-2I-AkI-Ek) restricted. Clonal segregation analyses revealed that the majority of clonally developing TNP-reactive Ly-2+ TL segregated into either IL 2 TL-p or cytotoxic T lymphocyte presursors, i.e. both functions appear to be mutually exclusive. Less than 10% of the responding Ly-2+ T cells seemed to be bifunctional. These findings provide compelling evidence for the L3T4+ T cell-independent, autonomous reactivity of Ly-2+ T cells in MHC-restricted antigen-specific responses and suggest T-T cell interactions within the functional heterogenous Ly-2+ T cell population.

In vitro stimulation of human granulocytes and lymphocytes by pico- and femtogram quantities of cytostatic agents

The influence of a broad concentration range of naturally occurring naphthoquinones and other cytotoxic or cytostatic agents (azathioprine, colchicine, cyclophosphamide, fluorouracil, methotrexate and vincristine) on human granulocytes and lymphocytes was investigated in a systematic in vitro study. At high concentrations (100 micrograms-10 ng/ml) nearly all substances showed the known cytotoxic or immunosuppressive effects, whereas most of the same compounds displayed immunostimulating activities at very low concentrations (10 ng-10 fg/ml). After a cold shock or heat treatment lymphocytes became more sensitive against these compounds in the active concentration range than untreated cells. These results possibly give an explanation for the antitumour activity of some plant extracts, for which a direct cytotoxicity due to the applied low dose can be excluded.

[Immunologic in vivo and in vitro studies on Echinacea extracts]

Ethanolic extracts of Echinacea purpurea, E. pallida and E. angustifolia roots were examined for immunological activity in the carbon clearance test with mice and in the granulocyte test. In the in vivo experiment all extracts, administered orally, were found to enhance phagocytosis significantly. These results correlate with the stimulation of phagocytosis in the in vitro granulocyte test. The lipophilic fractions of the extracts appeared to be more active than the polar fractions. All extracts were analyzed by HPLC in order to correlate the chemical constituents with the immunological activities.

Primary activation of murine CD8 T cells via cross-linking of T3 cell surface structures: two signals regulate induction of interleukin 2 responsiveness

In the model system used here to study the minimal signal requirements for the activation of murine resting CD8 T cells, cross-linking of T cell receptor structures by antigen-presenting cells is substituted for by the use of anti-CD3 monoclonal antibodies immobilized in Sepharose beads. We show that cross-linking of CD3 structures, even in combination with CD8 structures, is necessary but insufficient to induce responsiveness to the growth-promoting effect of interleukin 2 (IL2), i.e. fails to induce expression of functional IL2 receptors. A macrophage cell line product termed IL2 receptor-inducing factor (RIF), but not IL1, IL3, IL4 or tumor necrosis factor, efficiently functions as costimulator. Once activated, growth of CD8 T cells is entirely driven by IL2. We conclude that two restriction points control the activation of resting CD8 T cells. While cross-linking of CD3 structures is essential as a first step, RIF is required as competence factor to induce IL2 responsiveness. We consider the possibility that the ability of antigen-presenting cells to produce RIF determines the immunogenicity of presented antigen towards antigen-reactive resting CD8 T cells.

Acute and long-term effects of low-density lipoprotein apheresis on the serum concentrations of vitamins E and A

Serum alpha-tocopherol and retinol concentrations were followed in four heterozygous adults and one homozygous child with familial hypercholesterolemia being treated by regular low-density lipoprotein (LDL) apheresis. Approximately 50% of plasma alpha-tocopherol was eliminated during a single apheresis procedure in the heterozygous adults, while a complete elimination of this vitamin along with LDLs was observed in the homozygous child. Absolute losses of alpha-tocopherol amounted to 13.4-22.5 mg/apheresis and are equivalent to the recommended dietary intake for 1.5 to 2 days. Despite these losses, no changes were observed either in serum alpha-tocopherol levels or in the ratio of alpha-tocopherol/total serum lipids after 12 months regular apheresis treatment. Serum retinol concentrations only showed a small decrease on apheresis, there being apparently no specific elimination of this vitamin. The absolute losses ranged from 42-422 micrograms/apheresis and were, therefore, much lower than the recommended dietary intake of the equivalent of 1500 micrograms retinol/day. It is concluded that no extra supplementation of these vitamins is required during LDL-apheresis therapy, although it may be advisable to monitor vitamin E status in patients on long-term, intensive therapy.

L3T4+ T-cell-independent reactivity of Lyt2+ T cells in vivo

The aim of this study was to analyze in vivo the L3T4+ T-cell-subset-independent reactivity of Lyt2+ T cells toward transplantation alloantigens. To this end, we depleted normal mice of L3T4+ T cells by injection of monoclonal antibodies to the L3T4 antigen. This procedure not only led phenotypically to a disappearance of L3T4+ T cells, but also effectively abolished reactivity toward class II MHC antigens in vitro and in vivo. However, L3T4+ T-cell-depleted mice still reacted to class I MHC alloantigens in vivo: after immunization with class I MHC alloantigens Il-2 receptor-bearing T cells appeared in the draining lymph nodes, and developed antigen-specific cytolytic activity. Moreover, upon in vivo priming the frequencies of class I MHC-specific precursors of Il-2-producing and cytolytic Lyt2+ T lymphocytes increased up to 20-fold. L3T4+ T-cell-depleted mice rejected class I MHC-bearing skin grafts promptly. We conclude that not only in vitro but also in vivo Lyt2+ T cells remain reactive toward class I MHC antigens in the absence of L3T4+ T helper cells.

[IgG subclass deficiency in childhood. Changes in the antigen specific immune response and significance of low IgG4 level]

The definition of IgG subclass deficiency and the correlations between low IgG subclass serum concentrations and high incidence of infections in certain patients are still obscure. Therefore 260 children from 6 months to 18 years with severe recurrent infections or a known immunodeficiency were screened for IgG subclass deficiency. Nine patients with severe IgG2 deficiency (Ig2 less than 0.3 g/l) and 35 patients with non-detectable IgG4 in immunoprecipitation were detected. One of these patients had a concomitant IgA deficiency, eight revealed an additional IgA and IgG2 deficiency, two an IgA, IgG2, and IgG3 deficiency, eighteen an IgG2 deficiency and one patient an IgG2 and IgG3 deficiency. The proportion of patients with non-detectable IgG4 in immunoprecipitation was 13.5% and thus in the same order of magnitude as described in the literature for healthy people. Our data show that there is no relation between low IgG4 serum levels and the increased occurrence of severe infections. In all patients investigated with non-detectable IgG4 in immunoprecipitation the gene for the heavy chain gene constant domain C gamma 4 could be detected by Southern blotting. Using a sensitive ELISA method IgG4 could be directly demonstrated in all patients at a serum level of 0.5-29 micrograms/ml. Specific IgG4 antibodies against protein antigens could not be detected in IgG4-deficient patients. Nevertheless total IgG antibodies against diphtheria and tetanus toxoid reached protecting titers. Patients with IgG2 deficiency showed an impaired immune response against polysaccharides from pneumococci and haemophilus influenzae type b.

Concentration and purification of plant pathogenic viruses by field step electrophoresis

Concentration and purification of plant pathogenic viruses by field step electrophoresis comprises a new and rapid preparative method with high throughput and short separation time. With this technique and combinations of field step and zone electrophoresis it is possible to purify plant pathogenic viruses from several contaminants in one separation step. Another application of field step electrophoresis allows the separation of viruses from each other.

Frequency of herpes simplex virus-specific murine cytotoxic T lymphocyte precursors in mitogen- and antigen-driven primary in vitro T cell responses

The aim of this study was to assess and to compare the frequencies and specificities of herpes simplex virus (HSV)-specific cytotoxic T lymphocyte precursors (CTL-p) in mitogen (concanavalin A)-activated splenic T cells, as well as in antigen-activated splenic T cells of normal nonimmunized mice. In the mitogen-driven system one of 130 T cell blasts developed clonal progenies able to lyse specifically HSV-infected syngeneic targets. In the antigen-driven system HSV-specific CTL-p could be detected in normal lymphocytes provided the stimulator cells used were enriched for dendritic cells and pulsed with high concentrations of heat-inactivated HSV. Depending on the mouse strain used, the frequencies of HSV-specific CTL-p ranged from 1/500 to 1/10,000 in normal mice. Upon antigen priming within local lymph node cells, an increase of frequencies from 1/500 to 1/170 was observed in CBA/Ca mice.

Frequency of herpes simplex virus-specific murine cytotoxic T lymphocyte precursors in mitogen- and antigen-driven primary in vitro T cell responses

The aim of this study was to assess and to compare the frequencies and specificities of herpes simplex virus (HSV)-specific cytotoxic T lymphocyte precursors (CTL-p) in mitogen (concanavalin A)-activated splenic T cells, as well as in antigen-activated splenic T cells of normal nonimmunized mice. In the mitogen-driven system one of 130 T cell blasts developed clonal progenies able to lyse specifically HSV-infected syngeneic targets. In the antigen-driven system HSV-specific CTL-p could be detected in normal lymphocytes provided the stimulator cells used were enriched for dendritic cells and pulsed with high concentrations of heat-inactivated HSV. Depending on the mouse strain used, the frequencies of HSV-specific CTL-p ranged from 1/500 to 1/10,000 in normal mice. Upon antigen priming within local lymph node cells, an increase of frequencies from 1/500 to 1/170 was observed in CBA/Ca mice.

Treatment toxicity reduction: breast cancer

Since curative treatment of advanced breast cancer is still beyond our reach, the importance of reducing overall toxicity of systemic treatment must be stressed. This seems to be possible by adapting the form and intensity of therapy to the prognosis and stage of disease and by using drugs exhibiting high antitumoral efficacy combined with low systemic toxicity. In 475 patients with metastatic breast cancer, we initiated a prognosis-oriented therapeutic strategy. We developed a prognostic score so as to classify patients into 'high' and 'low' risk groups. In this way we were able to separate patients into two groups with statistically different survival times. In addition, we found that the impact of the first polychemotherapy on survival is different when comparing patient with favourable and unfavourable prognostic scores. Patients with favourable prognostic factors had exactly the same survival time independent of tumour progression, stable disease or even partial remission. Only patients achieving a complete remission survived longer. In contrast, patients with unfavourable prognostic factors apparently benefited from chemotherapy. Patients achieving stable disease or objective tumour remission had a significantly longer survival time than those patients with immediate tumour progression. Additionally, for most of the patients in this group, chemotherapy induced a transient stabilization or improvement of tumour induced symptoms. Therefore, we conclude that chemotherapy of advanced breast cancer is necessary. However, to reduce overall toxicity, it must be planned and administered according to the prognostic picture of the individual patient.

Clonal specificity analysis of mitogen-activated murine T lymphoblasts

We have determined the frequencies and specificities of MHC-reactive and MHC-restricted cytotoxic T lymphocyte precursors (CTL-p) in mitogen (ConA)-activated splenocytes of normal unprimed mice. The limiting dilution (LD) system supported the growth of one out of three Lyt2+ T cell blasts. The generated CTL-populations lysed blast cell targets specifically as determined by split well analyses. MHC-gene product expression was necessary for lysis to occur, since MHC-negative F9 teratocarcinoma cells were not lysed. The frequency determinations and split well analyses revealed: 1) equally high numbers (approximately 1/100) of CTL-p that generated specific allo-MHC or self-MHC reactive CTL populations, 2) high frequencies of CTL-p which recognized hapten (TNP) or minor H (MH)-antigens in the context of self MHC or allo-MHC determinants. The results are discussed with respect to antigen, restriction and receptor specificities of mitogen-activated unprimed T cell blasts.

Representation of interaural time difference in the central nucleus of the barn owl's inferior colliculus

This paper investigates the role of the central nucleus of the barn owl's inferior colliculus in determination of the sound-source azimuth. The central nucleus contains many neurons that are sensitive to interaural time difference (ITD), the cue for azimuth in the barn owl. The response of these neurons varies in a cyclic manner with the ITD of a tone or noise burst. Response maxima recur at integer multiples of the period of the stimulating tone, or, if the stimulus is noise, at integer multiples of the period corresponding to the neuron's best frequency. Such neurons can signal, by means of their relative spike rate, the phase difference between the sounds reaching the left and right ears. Since an interaural phase difference corresponds to more than one ITD, these neurons represent ITD ambiguously. We call this phenomenon phase ambiguity. The central nucleus is tonotopically organized and its neurons are narrowly tuned to frequency. Neurons in an array perpendicular to isofrequency laminae form a physiological and anatomical unit; only one ITD, the array-specific ITD, activates all neurons in an array at the same relative level. We, therefore, may say that, in the central nucleus, an ITD is conserved in an array of neurons. Array-specific ITDs are mapped and encompass the entire auditory space of the barn owl. Individual space-specific neurons of the external nucleus, which receive inputs from a wide range of frequency channels (Knudsen and Konishi, 1978), are selective for a unique ITD. Space-specific neurons do not show phase ambiguity when stimulated with noise (Takahashi and Konishi, 1986). Space-specific neurons receive inputs from arrays that are selective for the same ITD. The collective response of the neurons in an array may be the basis for the absence of phase ambiguity in space-specific neurons.

Methylation of the enhancer region of avian sarcoma virus long terminal repeat suppresses transcription

The effect of methylation of an enhancer on transcription was studied. A 245 bp enhancer-containing a fragment of the LTR of the avian sarcoma virus was methylated in vitro and ligated back into a vector which lacked the upstream enhancer sequence. The transient expression in QT6 cells indicated that methylation of the enhancer-containing sequence severely reduced the extent of transcription.