Chicken major histocompatibility complex congenic lines differ in the percentages of lymphocytes bearing CD4 and CD8 antigens

In the experiments to be described two congenic inbred lines CB and CC and two recombinant lines CB.R1 and CC.R1 were used. All four lines differ only in regard to the major histocompatibility complex (MHC). To determine the percentage distributions of the two cell subsets in peripheral blood lymphocytes (PBL) in these lines, monoclonal antibodies to these two antigens were used. By FACScan there were more CD4+PBL in CB and CB.R1 lines (share B-F/B-L region, controlling class I/class II antigens with line CB) than CC and CC.R1, while the reverse was true with CD8+ subsets. There were more CD8+ PBL in the CC and CC.R1 lines and less in CB and CB.R1 lines. The ratio of CD4+ to CD8+ in CB chickens was 3.4 +/- 0.2 and in CC chickens 1.6 +/- 0.1.

On the fate of skeletal myoblasts in a cardiac environment: down-regulation of voltage-gated ion channels

We have analysed the voltage-gated ion channels and fusion competence of skeletal muscle myoblasts labelled with green fluorescent protein (GFP) and the membrane dye PKH transplanted into the infarcted myocardium of syngenic rats. After cell transplantation the animals were killed and GFP(+)-PKH(+) myoblasts enzymatically isolated for subsequent studies of ionic currents through voltage-gated sodium, calcium and potassium channels. A down-regulation of all three types of ion channels after engraftment was observed. The fraction of cells with calcium (68%) and sodium channels (65%) declined to zero within 24 h and 1 week, respectively. Down-regulation of potassium currents (90% in control) occurred within 2 weeks to about 30%. Before injection myoblasts expressed predominantly transient outward potassium channels whereas after isolation from the myocardium exclusively rapid delayed rectifier channels. The currents recovered completely between 1 and 6 weeks under cell culture conditions. The down-regulation of ion channels and changes in potassium current kinetics suggest that the environment provided by infarcted myocardium affects expression of voltage-gated ion channels of skeletal myoblasts.

Cyclin D3 and c-MYC control glucocorticoid-induced cell cycle arrest but not apoptosis in lymphoblastic leukemia cells

Glucocorticoids (GC) induce cell cycle arrest and apoptosis in lymphoblastic leukemia cells. To investigate cell cycle effects of GC in the absence of obscuring apoptotic events, we used human CCRF-CEM leukemia cells protected from cell death by transgenic bcl-2. GC treatment arrested these cells in the G1 phase of the cell cycle due to repression of cyclin D3 and c-myc. Cyclin E and Cdk2 protein levels remained high, but the kinase complex was inactive due to increased levels of bound p27(Kip1). Conditional expression of cyclin D3 and/or c-myc was sufficient to prevent GC-induced G1 arrest and p27(Kip1) accumulation but, importantly, did not interfere with the induction of apoptosis. The combined data suggest that repression of both, c-myc and cyclin D3, is necessary to arrest human leukemia cells in the G1 phase of the cell division cycle, but that neither one is required for GC-induced apoptosis.

Influence of cytokines tumor necrosis factor-alpha and interferon-gamma on signaling cascades associated with apoptosis in rat PC12 cells

During cell-mediated immune response, increased amounts of interferon-gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha) are released. In the present study, we investigated the potential of these two cytokines to mediate apoptosis and to alter signal transduction pathways involved in undifferentiated PC12 cells. To induce apoptosis, the pteridine 7,8-dihydroneopterin (NH2) was used. TNF-alpha alone and TNF-alpha in combination with IFN-gamma led to no alteration in cell viability during 48 h of incubation. TNF-alpha was able to slightly elevate apoptosis compared with cells stimulated with NH2 alone. The combination of TNF-alpha and IFN-gamma almost completely abrogated the rate of apoptosis induced by NH2. Similar degrees of activation of extracellular protein kinase were found after the addition of cytokines or cytokines in combination with NH2. Stress-activated protein kinase (SAPK) was not activated by the cytokines alone, whereas adding the cytokine TNF-alpha to NH2-stimulated cells resulted in activation of SAPK after 15 min.

CD4(+)CD8(+)TCR(low) thymocytes express low levels of glucocorticoid receptors while being sensitive to glucocorticoid-induced apoptosis

While signaling by either the TCR or glucocorticoid receptor (GR) can induce apoptosis in thymocytes, recent studies have shown that combining these signals results in survival of CD4(+)CD8(+) thymocytes. Although glucocorticoids (GC) in this way may directly affect T cell selection, no data are available addressing GR expression in thymocyte subsets and in individual cells within subsets. We studied GR expression by combining immunofluorescence cell surface staining for CD4, CD8 and TCR with intracellular staining of GR in four-color cytometry. Significant differences of GR expression were observed in various thymocyte subsets, although a homogeneous distribution of GR expression in individual thymocyte subsets emerged. The highest GR expression was found in CD4(-)CD8(-)TCR(-) thymocytes, and decreased during development via the CD4(-)CD8(+)TCR(-) subpopulation into the CD4(+)CD8(+)TCR(low) subset. Interestingly, the latter population, although expressing less than half the GR density of CD4(-)CD8(-)TCR(-) cells, is the most sensitive subset to GC-induced apoptosis. Up-regulation of TCR expression by the CD4(+)CD8(+)TCR(low) subset to CD4(+)CD8(+)TCR(high) cells was accompanied by a parallel increase in GR expression. The latter finding and the presence of a homogeneous distribution of GR in each thymocyte subset provides an experimental basis for the concept that GR can antagonize TCR-mediated signals at a constant rate relative to TCR expression.

Double-blind, placebo-controlled psychometric studies on the effects of a combined estrogen-progestin regimen versus estrogen alone on performance, mood and personality of menopausal syndrome patients

The influence of a combined estrogen-progestin regimen (Climodien) on noopsyche, thymopsyche, personality and psychophysiological measures of menopausal syndrome patients was investigated in a double-blind, placebo-controlled, comparative, randomized 3-arm trial phase (Climodien 2/3 = estradiol valerate (CAS 979-32-8) 2 mg + the progestin dienogest (CAS 65928-58-7) 3 mg = regimen A, estradiol valerate 2 mg = regimen EV, and placebo = regimen P) followed by an open-label phase in which all patients received Climodien 2/2 (estradiol valerate 2 mg + dienogest 2 mg) = regimen A*. 49 women (16, 17, 16 valid patients per arm) aged between 46 and 67 years (mean 58, 58, 56 years, respectively) with the diagnoses of insomnia (G 47.0) related to postmenopausal syndrome (N 95.1) were included in the analysis of the double-blind phase. Both the double-blind and the open-label phase lasted 2 months. Noopsychic investigations demonstrated an improvement in associative verbal memory after 2 months of regimen A, which was significant as compared with both baseline and placebo. Regarding visual memory, regimen A* induced an improvement, which was significantly different from the decline in correct reproductions in the Benton Test observed under estradiol. Errors in the Benton Test decreased significantly after regimen A* as compared with regimen EV. These findings suggest that hormone replacement therapy with estradiol, and even more in combination with dienogest, improves verbal and visual memory, which is in line with the improvement in information processing speed and capacity objectified by event-related potentials (ERP). Thymopsychic investigations demonstrated a significant improvement in somatic complaints and trait anxiety after both regimen A and regimen EV as compared with baseline. State anxiety decreased significantly under regimen A* as compared with EV. The Freiburger Personality Inventory showed an improvement in aggressivity after regimen A* as compared with the preceding placebo as well as an improvement in striving after dominancy after both regimen A and regimen EV as compared with pre-treatment, but also after regimen A* as compared with regimen EV. Extraversion increased after 2 months of regimen A as compared to regimen P. Psychophysiological findings including pupillary and skin conductance variables were not significant.

Induction of apoptosis by 7,8-dihydroneopterin: involvement of radical formation

Interferon-gamma is a cytokine released in large amounts during cell-mediated immune response. It induces the expression of proinflammatory cytokines and enhances macrophage capacity to secrete reactive oxygen intermediates and the pteridines neopterin and 7,8-dihydroneopterin. To assay the role of these pteridines in the immune system several studies were performed. Thereby, 7,8-dihydroneopterin was found to induce apoptosis in T lymphocytes. In this study we report that caspases are involved in 7,8-dihydroneopterin-mediated apoptosis in Jurkat T cells. In connection with this result we found that 7,8-dihydroneopterin can increase Fas ligand expression detected in Western blot analysis and promoter reporter assays. Antioxidants potently reduced the effect of 7,8-dihydroneopterin on Fas ligand promoter activation suggesting an involvement of oxidative stress. In further investigations, ESR-measurements were performed to evaluate the role of 7,8-dihydroneopterin in the formation of radicals. We found that the pteridine in combination with the spin trap DMPO induces the production of DMPO-OH spin adducts. This reaction was sensitive to the presence of chelated metal ions and could completely be blocked by the addition of superoxide dismutase. These data suggest that 7,8-dihydroneopterin in aqueous solution leads to the formation of .OH radicals via generation of superoxide anion. We hypothesize that an overproduction of radicals caused by high levels of 7,8-dihydroneopterin is likely to be responsible for the pro-apoptotic effects observed in cell cultures and possibly contributes to the pathogenesis of diseases involving immune activation and elevated concentrations of neopterin-derivatives.

Reduced pteridine derivatives induce apoptosis in human neuronal NT2/HNT cells

Elevated concentrations of the pteridine compound neopterin, usually accompanied by 7,8-dihydroneopterin were found in cerebrospinal fluids of patients with neurodegenerative diseases and central nervous system infections. Here, the potential of pteridines to induce apoptosis of the human neuronal cell line (NT2) was investigated. Reduced neopterin, biopterin- and folate derivatives led to a time-dependent increase of apoptosis of cells. In contrast, non-reduced pteridines did not significantly alter cell survival. After differentiation of neuronal precursor cells to neurons and astrocyte-like cells, similar effects were detected. Antioxidants partly protected NT2 from pteridines-induced apoptosis, suggesting the involvement of reactive oxygen intermediates. In vitro experiments using dichlorofluorescin-diacetate further indicated a direct formation of reactive oxygen species in cells. Results implicate that high concentrations of reduced pteridines, might contribute to the loss of neuronal cells in neurodegenerative diseases.

Identification of syntenin as a protein of the apical early endocytic compartment in Madin-Darby canine kidney cells

We used flow cytometry to sort and analyze apical and basolateral endocytic vesicles from filter-grown Madin-Darby canine kidney (MDCK) cells after membrane internalization of the lipophilic fluorescent probe trimethylamino-diphenylhexatriene. Western blot analysis of sorted fractions showed enrichment of the early endosomal markers transferrin receptor and the small GTPase Rab5. Two-dimensional gel analysis indicated that the apical and basolateral early endosomes differed significantly in their protein composition. We found nine polypeptides to be specifically enriched in apical or basolateral endocytic vesicles. An apical protein identified by microsequencing was the adaptor molecule syntenin. This protein contains two PDZ domains (PSD-95, Dlg, and ZO-1 homology) that bind syndecan and ephrin-B2 cytoplasmic domains. In MDCK cells, transiently overexpressed Myc-tagged syntenin localized to both plasma membrane domains and to an intracellular vesicular compartment. Syntenin positive vesicles colocalized with internalized transferrin in the perinuclear region. In addition, syntenin colocalized in the apical supranuclear region with Rab5 and Rab11; the latter is a marker for the apical recycling endosomes in MDCK cells.

Flow-cytometric evaluation of oxidative burst in phagocytic cells of children with cystic fibrosis

OBJECTIVES

The objective of this study was to assess the dye 2', 7'-dichlorofluorescein (DCF) assay in screening for alterations in polymorphonuclear cell (PMN) and monocyte (MC) oxidative burst of cystic fibrosis (CF) patients.

STUDY DESIGN

56 CF patients aged between 2 and 20 years were investigated. Purified cells were stimulated with phorbolmyristate acetate (PMA) and zymosan (ZX). A range for DCF fluorescence for PMA- and ZX-stimulated and non-stimulated cells was established based on data from 60 healthy controls.

RESULTS

PMNs showed both enhancement and impairment. A deficient oxidative burst was detected in a total of 14 CF patients caused by abnormally high mean fluorescence intensity (MFI) of resting cells. Enhanced oxidative burst was seen in 6 CF patients. CF patients responded differently to PMA or ZX stimulation. Pseudomonas aeruginosa colonization significantly enhanced (p<0.005) the MFI of resting PMNs. MCs of CF patients showed a significantly (p<0.05) enhanced oxidative burst after stimulation with PMA compared to healthy controls, but no differences could be observed after stimulation with ZX. Serum concentrations of interleukin-6 were elevated in all CF patients, in particular in those with activation of both PMNs and MCs.

CONCLUSION

The DCF assay shows for the first time the heterogeneity of the oxidative burst reaction in CF patients. In our opinion, the DCF assay is a reliable method for detecting pathological oxidative burst in CF patients.

Genes of chicken MHC regulate the adherence activity of blood monocytes in Rous sarcomas progressing and regressing lines

The influence of the chicken major histocompatibility (B) complex (MHC) on the adherence potential of monocyte-derived macrophages was examined using the congenic chicken lines CB and CC. These lines represent well-defined genetic models for the study of resistance (CB) or susceptibility (CC) to the progressive growth of Rous sarcomas. Using a monoclonal antibody specific for chicken monocytes/macrophages, CB and CC chickens were shown by flow cytometry analyses to have similar proportions of peripheral blood monocytes. However, when the glass-adherence potential of these cells was compared during incubation in tissue culture medium over 24, 48 and 72 h at 40 degrees C, significant differences were seen between cells from these two inbred lines. After 24 and 48 h, glass-adherence by CB cells was 2-3 fold higher than that of CC cells. After 72 h this difference decreased to 1.5 fold. At 24 and 48 h, the adherent CB macrophages also appeared about 1.5 times larger than those of CC chickens. Genetic analysis using F1 hybrids (CBxCC) showed that this trait is regulated by a dominant gene that segregates with the B12 haplotype in the backcross generation F1xCC. From the results obtained with the recombinant congenic lines CB.R1 and CC.R1, we conclude that the gene regulating adherence potential is localized within the B-F/L region of the chicken MHC. About 50% of adherent cells were able to phagocytose opsonised FITC-labelled Zymosan particles. The level of nitric oxide production in vitro by CB and CC macrophages was equal. The importance of cells of the mononuclear phagocyte system for the response to Rous sarcoma virus (RSV) infection was studied in CB chickens using the anti-macrophage agents silica, carrageenan, and C12MDP, encapsulated in liposomes. In those chickens treated with silica and carrageenan, we observed progressive growth of RSV-induced tumors. The graft-versus-host reactivity of peripheral blood lymphocytes (PBL) of treated chickens was comparable to controls. In vitro nitric oxide production by macrophages from silica-treated chickens was higher than by macrophages from untreated controls.

7,8-Dihydroneopterin-induced apoptosis in Jurkat T lymphocytes: a comparison with anti-Fas- and hydrogen peroxide-mediated cell death

Activated cell-mediated immunity, associated for example with HIV infection, is accompanied by elevated concentrations of neopterin and 7,8-dihydroneopterin. Recent data have indicated a role of neopterin derivatives in virus activation and apoptotic cell death, processes likely to involve the action of oxygen free radicals. Because T cell death in AIDS is likely to involve the Fas/Fas ligand system and the action of oxygen free radicals and 7,8-dihydroneopterin, we compared the kinetics and sensitivity of apoptotic cell death of human leukemic Jurkat T cells to that of treatments with 7,8-dihydroneopterin, anti-Fas, and H2O2. Upon incubation with 5 mM 7,8-dihydroneopterin and 50 microM hydrogen peroxide over a period of 24 hr, bimodal kinetics were observed with peaks at 5.5 hr (7,8-dihydroneopterin, 13.1%; H2O2, 11.4%) and at 24 hr (7,8-dihydroneopterin, 11.2%; H2O2, 13.2%). In contrast, anti-Fas (20 ng/mL)-induced apoptosis increased steadily over time, peaking at 11 hr (43.2%). Interestingly, anti-Fas-induced apoptosis was suppressed upon co-incubation with 7,8-dihydroneopterin and H2O2 by 62% and 68%, respectively. We also compared the sensitivity to drug treatments of apoptosis induced by 7,8-dihydroneopterin, anti-Fas antibodies, and H2O2. 7,8-Dihydroneopterin-mediated, and similarly anti-Fas- and H2O2-mediated, apoptosis was not inhibited by a broad range of pharmacological inhibitors, such as actinomycin D, cycloheximide, cyclosporin A, and various protein kinase inhibitors. On the contrary, inhibitors with antioxidant abilities, such as pyrrolidinedithiocarbamate, significantly blocked 7,8-dihydroneopterin-, H2O2- as well as anti-Fas-mediated apoptosis. These results imply that 7,8-dihydroneopterin-, H2O2-, and anti-Fas-mediated cell death might involve related redox sensitive signal transduction pathways.

Activation of PDGF receptor alpha in vascular smooth muscle cells by mechanical stress

Hypertension increases mechanical force on the arterial wall by as much as 30%, resulting in marked alterations in signal transductions and gene expression in vascular smooth muscle cells (VSMCs) that contribute to matrix protein synthesis, cell proliferation, and differentiation. How the mechanical stimuli are converted into a biological signal in cells has yet to be studied. We investigated the role of both cyclic strain and shear stresses in initiating the cellular signaling on cultured VSMCs and found that mechanical forces evoked activation of mitogen-activated protein kinases, followed by enhanced DNA binding activity of transcription factor AP-1. Physical forces rapidly induced phosphorylation of platelet-derived growth factor receptor (PDGFR) alpha, an activated state. When GRB2, an adapter protein, was immunoprecipitated from treated VSMCs followed by Western blot analysis with anti-phosphotyrosine, -PDGFR alpha, and -GRB2 antibodies, respectively, phosphotyrosine positive staining was observed on PDGFR alpha bands of the same blot in stretch-stressed VSMCs, supporting the mechanical stress-induced activation of PDGFR alpha. Conditioned medium from stretch-stressed VSMCs did not result in PDGFR alpha phosphorylation, and antibodies binding to all forms of PDGFs did not block stress-induced PDGFR alpha activation. Thus, mechanical stresses may directly perturb the cell surface or alter receptor conformation, thereby initiating signaling pathways normally used by growth factors.

Irradiation induces G2/M cell cycle arrest and apoptosis in p53-deficient lymphoblastic leukemia cells without affecting Bcl-2 and Bax expression

The tumor suppressor p53 has been implicated in gamma irradiation-induced apoptosis. To investigate possible consequences of wild-type p53 loss in leukemia, we studied the effect of a single dose of gamma irradiation upon p53-deficient human T-ALL (acute lymphoblastic leukemia) CCRF - CEM cells. Exposure to 3 - 96 Gy caused p53-independent cell death in a dose and time-dependent fashion. By electron microscopic and other criteria, this cell death was classified as apoptosis. At low to intermediate levels of irradiation, apoptosis was preceded by accumulation of cells in the G2/M phase of the cell division cycle. Expression of Bcl-2 and Bax were not detectably altered after irradiation. Expression of the temperature sensitive mouse p53 V135 mutant induced apoptosis on its own but only slightly increased the sensitivity of CCRF - CEM cells to gamma irradiation. Thus, in these, and perhaps other leukemia cells, a p53- and Bcl-2/Bax-independent mechanism is operative that efficiently senses irradiation effects and translates this signal into arrest in the G2/M phase of the cell cycle and subsequent apoptosis.

Environmental influence on age-related changes of human lymphocyte membrane viscosity using severe combined immunodeficiency mice as an in vivo model

Peripheral blood lymphocytes (PBL) of healthy elderly people show increased plasma membrane viscosity compared to young subjects, that inversely correlates with lymphocyte proliferation after mitogen stimulation in vitro. Maintenance of a constant membrane viscosity, which is necessary for proper cell function, is crucially dependent on the membrane lipid composition. The cellular lipid metabolism, and thus lymphocyte function, may be subject to modulation by diet or drugs. To study the susceptibility of membrane viscosity to environmental conditions, we established an in vivo model using severe combined immunodeficiency (SCID) mice: human peripheral blood lymphocytes from healthy young and old subjects were engrafted for three days intraperitoneally into SCID mice to offer identical environmental conditions. First, we demonstrate that human lymphocytes can take up and utilize murine lipoproteins: engrafted human PBL can participate in the mouse lipid metabolism, and an exchange of membrane lipids in vivo is, therefore, possible. Second, plasma membrane viscosity was determined before and after engraftment: before engraftment, PBL from the elderly showed a significantly higher membrane viscosity than that from young controls, but this difference vanished during engraftment into SCID mice, wherein cells from both age groups exhibited nearly identical values. It was, therefore, concluded that lymphocyte membrane viscosity is influenced by environmental factors, and that the age-related increase is, in principle, reversible.

Human monocyte-derived dendritic cells produce macrophage colony-stimulating factor: enhancement of c-fms expression by interleukin-10

Human monocyte-derived dendritic cells (DC) generated with granulocyte-macrophage colony-stimulating factor (GM-CSF) and IL-4 express c-fms (CD115), the receptor for macrophage-CSF (M-CSF). Expression of c-fms on monocyte-derived DC has been interpreted as the susceptibility of these cells to M-CSF-induced macrophage development. We show here that homogeneous cultures of CD14 DC constitutively produced large amounts of M-CSF. However, presence of M-CSF neither induced macrophage development nor did it prevent terminal maturation into CD83+ DC. M-CSF production by DC was driven by GM-CSF and inhibited by the specific phosphatidylinositol 3-kinase inhibitor wortmannin. M-CSF synthesis was rapidly induced during the first 24 h of DC culture and then declined during the 5-day culture period. Replating of the cells, which was associated by a transient adherence, always induced a strong up-regulation of M-CSF synthesis. Addition of recombinant IL-10 to DC cultures enhanced c-fms expression and induced macrophage development as measured by the strong up-regulation of CD14 expression as well as by enhanced expression of the Fcgamma receptors I, II, and III (CD64, CD32, CD16). Our data demonstrate that immature monocyte-derived DC produce M-CSF which does not induce macrophage development, despite the surface expression of c-fms on DC. IL-10 appears to induce macrophage development by up-regulating c-fms and, thereby, enhancing the sensitivity of the cells to endogenously produced M-CSF.

Differential deactivation of human dendritic cells by endotoxin desensitization: role of tumor necrosis factor-alpha and prostaglandin E2

The endotoxin (lipopolysaccharide)-induced cytokine response is followed by a state of unresponsiveness to lipopolysaccharide (LPS) referred to as LPS tolerance or endotoxin desensitization. LPS tolerance, which can be experimentally induced in vitro and in vivo, is also known to occur in septic disease. Here, we evaluated whether dendritic cells (DC), the most potent antigen-presenting cells, are also subject to this phenomenon. Single doses of LPS added at the initiation of DC culture inhibited in a dose-dependent fashion the production of tumor necrosis factor-alpha (TNF-alpha), interleukin-10 (IL-10), and IL-12, but not the production of IL-8, in response to a second LPS challenge in day-5 DC. In addition, the LPS-induced expression of the CD83 maturation antigen was inhibited in these cells. Moreover, the endocytic activity of DC generated in the presence of LPS was dramatically reduced. DC desensitized with LPS were potent stimulators of T-cell proliferation but poor inducers of interferon-gamma (IFN-gamma) production in the allogeneic mixed leukocyte reaction. TNF-alpha and prostaglandin E2, two major products of LPS stimulation, could replace LPS for the induction of tolerance to LPS. Moreover, treatment of desensitized DC with TNF-alpha plus prostaglandin E2 fully restored CD83 expression and partially restored IL-12 production as well as the IFN-gamma-inducing activity of DC in the mixed leukocyte reaction. Our data show that human DC are highly susceptible to the induction of LPS tolerance, which seems to be a state of differential deactivation in which some functions are impaired whereas others are retained. Tolerization at the level of the professional antigen-presenting cell by inflammatory mediators may play an important role in septic disease and in the origin of cancers associated with chronic inflammation.

Cell biologists sort things out: Analysis and purification of intracellular organelles by flow cytometry

Flow cytometry was established originally for measuring DNA content and for the analysis of cell-surface markers in combination with cell sorting. During the past two decades, it has added new dimensions to various areas of immunology and medicine. Increased sensitivity and precision of flow cytometers, accompanied by the development of new fluorescent dyes and probes, has led to new applications in molecular cell biology and genetics. This article focuses on applications of flow cytometry in analysis and sorting of intracellular organelles.

Prostaglandin E2 and tumor necrosis factor alpha cooperate to activate human dendritic cells: synergistic activation of interleukin 12 production

Interleukin (IL)-12 is a proinflammatory cytokine that contributes to innate resistance and to the development of antigen-specific T cell responses. Among other effects, prostaglandin E2 (PGE2) inhibits the production of IL-12 by macrophages activated with lipopolysaccharide (LPS). Here we investigated the effects of PGE2 on human dendritic cells (DCs) which develop in the presence of GM-CSF and IL-4. We demonstrate that in the absence of LPS, PGE2 dose dependently stimulated the production of IL-12 by DCs. Although PGE2 alone stimulated the production of low amounts of IL-12 only, it synergized with tumor necrosis factor (TNF)-alpha to induce high levels of IL-12 production by DCs. Addition of TNF-alpha in the absence of PGE2 had no effect on IL-12 production. Conversely, in the presence of LPS, PGE2 inhibited IL-12 production by DCs in a dose-dependent manner. The combination of PGE2 and TNF-alpha efficiently silenced mannose receptor-mediated endocytosis in DCs and readily induced neo-expression of the CD83 antigen. In addition, the expression of various surface antigens such as major histocompatibility complex class I and II, adhesion, as well as costimulatory molecules was upregulated by this treatment. The effects of PGE2 on IL-12 synthesis and CD83 expression could be mimicked by dibutyryl-cAMP and forskolin, indicating that they were due to the intracellular elevation of cAMP levels. DC treated with PGE2 and TNF-alpha were most potent in stimulating allogeneic T cell proliferation. Our data demonstrate that PGE2 contributes to the maturation of human DCs and that PGE2 can be a potent enhancer of IL-12 production by human DCs.

Comparative studies on the effects of the combination drug lorazepam plus diphenhydramine (Somnium) versus lorazepam on the noopsyche, thymopsyche and psychophysiology in nonorganic insomnia related to generalized anxiety disorder

In a double-blind, parallel-group design study on hypnotic and anxiolytic effects of the combination drug Somnium (lorazepam 1 mg + diphenhydramine 25 mg) (SOM) as compared with 1 mg lorazepam (LOR) alone, daytime behavioral effects were studied in 44 patients with nonorganic insomnia related to a mild generalized anxiety disorder. After a placebo run-in phase of 1 week, they received active treatment for 4 weeks. Psychometric evaluations included 6 thymopsychic variables (somatic complaints, state anxiety, trait anxiety, self-rating anxiety and depression scale and adjective mood scale), 6 noopsychic variables (general, associative, numerical and total verbal memory; correct reproductions and errors-Benton visual memory test), 4 pupillary measures (pupillary diameter, latency, relative change in % and half recovery time in pupillary response) and 6 skin conductance measures (baseline, latency, ascending time, time to peak, skin conductance response and skin conductance response maximum). Multivariate statistical analysis of the thymopsyche demonstrated significant improvement after both compounds, with the combination drug significantly superior to its single component lorazepam. Also regarding noopsychic measures, Somnium was significantly superior to the single component lorazepam, as specifically verbal memory was improved after Somnium, while opposite changes occurred after lorazepam alone. Pupillary measures revealed no significant overall inter-drug differences, whereas skin conductance findings demonstrated that the combination drug Somnium was superior to the single component lorazepam also in regard to the anxiolytic effect at the autonomic nervous system level.

Dendritic cells generated from blood precursors of chronic myelogenous leukemia patients carry the Philadelphia translocation and can induce a CML-specific primary cytotoxic T-cell response

Dendritic cells (DC) are professional antigen-presenting cells specialized in the initiation of primary immune responses. We were interested to know whether mature DC can be grown in vitro from peripheral blood mononuclear cells (PBMC) of patients with chronic myelogenous leukemia (CML), and whether they carry the Philadelphia (Ph) translocation. Using a method recently described, DC were generated from PBMC precursors of 12 patients with CML using GM-CSF, IL-4, and monocyte-conditioned medium. DC exhibited the typical morphology with thin cytoplasmatic processes and expressed high levels of MHC class II, CD86, and CD83 typical for mature DC. After sorting with the monoclonal antibody CD83, a cell population of more than 95% CD83 positive cells was obtained. The presence of the Ph translocation was analyzed in these cells, in PBMC, lymphoblastoid cell lines (LCL), and in phytohemagglutinin (PHA)-induced T blasts from the same patients by fluorescence in situ hybridization (FISH). In contrast to all other cells analyzed, the vast majority of DC (95.9 +/- 0.7%) displayed the Ph translocation, irrespective of disease stage or therapy. PBMC were predominantly positive for the Ph chromosome (67.6 +/- 7.3%), whereas only 11.4 +/- 1% of the B cells and 4.4 +/- 1.1% of the PHA blasts carried the Ph translocation. Using such leukemic DC as antigen-presenting cells, a primary CML-directed cytotoxic immune response in vitro was obtained, as shown by the specific recognition of Ph chromosome positive cells. We conclude that DC can be generated from blood progenitors of CML patients in vitro and exhibit, to a large extent, the Ph translocation. Such DC, which in a preliminary experiment have been able to induce a primary CML-directed cytotoxic immune response in vitro, might be ideal candidates for adoptive immunotherapy either by direct transfer of DC for in vivo generation of a T-cell response or by in vitro generation of CML-specific cytotoxic autologous or HLA-matched normal T-cell clones for use in vivo.

Induction of apoptosis in Kaposi's sarcoma spindle cell cultures by the subunits of human chorionic gonadotropin

OBJECTIVES

Elucidation of the mechanisms of the previously shown growth-inhibitory action of human chorionic gonadotropin (hCG) on Kaposi's sarcoma (KS) cells and the role of the luteinizing hormone/hCG receptor (hCGR).

DESIGN AND METHODS

Analysis of KS tissues and cultured spindle-type KS cells for the presence of the hCGR using 125I-hCG binding and reverse transcriptase-polymerase chain reaction; analysis of several hCG preparations (urinary, recombinant, isolated alpha and beta subunits); analysis of apoptosis mechanisms by several assays including using z-Val-Ala-Asp-fluoromethylketone (zVAD-FMK), a known apoptosis-inhibitory drug.

RESULTS

First, we found that some urinary preparations of hCG (e.g., CG-10, Steris Profasi) were indeed KS-killing but others (such as Pregnyl, Choragon, Serono Profasi) were not. Secondly, recombinant subunits (alpha as well as beta) of hCG were KS cell-killing but recombinant intact hCG was not. Thirdly, the hCGR message and protein were undetectable in KS. Fourthly, CG10-induced cell death occurred by apoptosis and KS cells could be rescued by preincubation with zVAD-FMK. Finally, we also found that normal peripheral blood lymphocytes (PBL) were killed by CG-10.

CONCLUSION

It is proposed that the action of subunits or subunit fragments of hCG, mediated by a putative orphan receptor (as opposed to the hCGR) and executed by interleukin-1-converting enzyme (ICE)-like protease(s), constitutes a novel apoptosis mechanism effective towards KS cells, but PBLs and possibly other cells as well. These results provide a basis for testing in vitro the therapeutic efficacy of hCG preparations which, in turn, should improve current clinical trials with 'hCG' in patients who have KS.

Constitutive expression of Fas (Apo-1/CD95) ligand on multiple myeloma cells: a potential mechanism of tumor-induced suppression of immune surveillance

The Fas (Apo-1/CD95) ligand (FasL) plays a central role in the elimination of target cells by effector T lymphocytes and in the suppression of cellular immune responses against nonmalignant and malignant cells. We show the expression of FasL on the surface of neoplastic plasma cells. We provide evidence that the FasL is functionally active because five of five neoplastic plasma cell lines tested killed CEM-C7H2 T-acute lymphoblastic leukemia (T-ALL) cells. The effect was mediated via the Fas (Apo-1/CD95) receptor molecule because blocking of Fas on the target cells or the FasL on the tumor cells by receptor- and ligand-specific monoclonal antibodies (MoAbs), respectively, protected T cells from being killed by myeloma cells. In addition, overexpression of the cowpox virus protein CrmA, a molecule with inhibitory potential on caspase-1 and caspase-8, specifically involved in Fas-induced signaling, protected T cells from being destroyed by the neoplastic cells or the agonistic anti-Fas MoAb. The potential of the malignant plasma cells to extinguish target T cells was independent of their own sensitivity to the agonistic anti-Fas MoAb, and FasL-positive (FasL+) CEM-C7H2 T cells were incapable of killing myeloma cells. Our results suggest that tumor cell-induced suppression of the immune system may be exerted via the FasL active on malignant plasma cells. Furthermore, loss of Fas expression or insensitivity to the agonistic anti-Fas MoAb do not seem to be prerequisites for myeloma cells to defeat T cells via Fas/FasL interaction.

In vitro generation of CD83+ human blood dendritic cells for active tumor immunotherapy

There is increasing clinical interest in dendritic cells that are capable of initiating antitumor immune responses. Dendritic cells cultured from human blood mononuclear cells using granulocyte/macrophage colony-stimulating factor (GM-CSF) and interleukin-4 (IL-4) are competent for antigen uptake but express relatively low levels of costimulatory molecules and thus correspond to immature resident tissue dendritic cells. In this study we took advantage of the new dendritic cell-specific marker CD83, which is expressed by mature dendritic cells, to delineate the maturation of cultured human blood dendritic cells. Although dendritic cells cultured with GM-CSF and IL-4 contained transcripts for CD83 as determined by reverse transcription PCR, CD83 protein was barely detectable by flow cytometry, confirming that dendritic cells obtained with this system are immature. However, treatment of dendritic cells with tumor necrosis factor-alpha (TNF-alpha) significantly increased the levels of CD83 transcripts and induced CD83 protein expression in dendritic cells. In contrast to the initiation of dendritic cell culture, which was facilitated by high cell density (5 x 10(6) cells/mL), differentiation into CD83+ dendritic cells required a low cell concentration (0.5 x 10(6) cells/mL). At higher cell density (1 x 10(6) cells/mL), CD83 expression was suppressed and was almost completely prevented at 2 x 10(6) cells/mL. Induction of CD83 expression was accompanied by a strong upregulation of the costimulator B7-2 (CD86) on dendritic cells. While untreated CD83(-) dendritic cells efficiently internalized fluoresceinated Dextran, TNF-alpha treated CD83+ dendritic cells excluded these molecules, confirming that maturation of dendritic cells was associated with the silencing of the antigen-capturing machinery. Morphologically, CD83+ dendritic cells presented with pronounced cytoplasmic projections (veils) characteristic of mature dendritic cells. In summary, we show that cell density critically regulates dendritic cell development. Knowledge of the appropriate conditions for dendritic cell generation and maturation will be important in clinical immunotherapy settings.

Bacillus Calmette-Guérin mycobacteria stimulate human blood dendritic cells

Bacillus Calmette-Guérin (BCG) mycobacteria have been used as adjuvant in the active immunotherapy of various human cancers. In addition, dendritic cells, which are the most potent antigen-presenting cells, have been shown to be capable of initiating anti-tumor immune responses. Here we investigated the effects of BCG on dendritic cells cultured from human blood. Addition of BCG resulted in rapid homotypic adhesion of dendritic cells. Moreover, BCG concentrations ranging from 10(4) to 10(6) bacteria/ml enhanced expression of the dendritic-cell-maturation antigen CD83 and of the T-cell co-stimulator CD86 (B7-2) in a dose-dependent manner. Concomitant with the increase of CD83 and CD86 expression, the cells lost the ability to capture soluble antigens, as determined by the exclusion of fluoresceinated Dextran molecules. Strikingly, the same dosages of BCG-bacteria stimulated TNF-alpha-gene transcription and TNF-alpha-protein release from dendritic cells in a dose-dependent fashion. BCG infection of dendritic cells in the presence of a neutralizing antibody directed against TNF-alpha inhibited CD83 expression by more than 50% indicating that the BCG-induced maturation of dendritic cells was at least partially mediated by dendritic-cell-derived TNF-alpha. The finding that BCG activates the most potent antigen-presenting cells reveals a plausible immunological mechanism of the occasionally observed anti-tumor activity of BCG.

Modulation of Apo-1/Fas (CD95)-induced programmed cell death in myeloma cells by interferon-alpha 2

The Apo-1/Fas (CD95) antigen is known to be involved in the process of T cell-mediated target cell killing and has recently been shown to be expressed on myeloma cell lines and native malignant plasma cells. Several cytokines have been reported to interfere with spontaneous and even Apo-1/Fas-induced apoptosis, but no attempt has been made yet to investigate these interactions and the possible underlying mechanisms in myeloma cells. Since in myeloma patients Interferon (IFN)-alpha2 displays a profound therapeutic effect in vivo, which is usually attributed to its growth inhibitory and/or immunomodulatory capacity, we set out to study the potential interference of IFN-alpha2 with Apo-1/Fas-induced apoptosis. Contrary to expectations, IFN-alpha2 reduced the degree of apoptosis caused by the treatment of five Apo-1/Fas-sensitive myeloma cell lines with a Fas monoclonal antibody (mAb). Simultaneous application of IFN-alpha2 and Fas mAb was superior to the prolonged (i.e. >8 h) preincubation with the cytokine as far as inhibition of Apo-1/Fas-induced apoptosis was concerned. This effect of IFN-alpha2 was neither explained by a down-regulation of the Apo-1/Fas receptor nor caused by modulation of the expression levels of c-myc, bcl-2-, bcl-xL, bax- or p53 genes. IFN-alpha2 did not alter the Apo-1/Fas-induced activity of Mitogen-activated protein kinase (MAPK) 1 and did not inhibit the Apo-1/Fas-mediated proteolytic cleavage of ADP-ribosyltransferase, a substrate of Interleukin-beta1 converting enzyme (ICE) and homologues. However, activation of protein kinase C (PKC) by phorbol 12-myristate 13-acetate (PMA) mimicked the effects of IFN-alpha2. Furthermore, the bis-indolylmaleimide GF 109203X, a specific inhibitor of PKC, inhibited the effect of PMA as well as that of IFN-alpha2 on Apo-1/Fas-induced apoptosis. These results point to a PKC-dependent mechanism of transient interaction between the intracellular signaling along the IFN-alpha2 and the Apo-1/Fas pathway (downstream of MAPK signaling as well as of ICE homologues), which becomes exhausted by prolonged stimulation with the cytokine. According to our data IFN-alpha2, applied continuously and in high doses resembling the therapeutic situation in vivo, inhibits myeloma growth. However, based on the observed inhibitory effect of IFN-alpha2 on Apo-1/Fas-induced apoptosis, a partial inhibition of the natural immune surveillance on myeloma cells by endogenous IFN-alpha2 present in the bone marrow microenvironment of this malignancy should be investigated.

Glucocorticoid-receptor-gene defects and resistance to glucocorticoid-induced apoptosis in human leukemic cell lines

The application of glucocorticoids (GC3) in human leukemia is based on apoptosis induction but is often hampered by GC resistance. To delineate resistance mechanisms, we examined 5 GC-resistant leukemic cell lines, termed CEM-C7.R1-R5, isolated from the GC-sensitive human acute-T-cell-leukemic line, CCRF-CEM-C7, by selection in GC-containing medium. GC resistance was ascertained by analyzing cell-cycle progression, proliferation, and apoptosis. Radioreceptor assays revealed absence of ligand-binding activity in all clones, suggesting that defects in GC-receptor(GR) expression cause GC resistance. Analyses of the GR gene revealed that all but one (CEM-C7.R5) of the clones were heterozygous for the previously described L753F mutation. CEM-C7.R5 was either hemi- or homozygous for the L753F mutation and, hence, lacked a functional GR. Sequencing of the allele not carrying the L753F mutation of the other GC-resistant sub-lines revealed additional mutations in the GR gene in 3 cases: CEM-C7.R1 and R2 had a base-pair deletion in exon 9 (deltaT740) that resulted in a reading-frame shift and a pre-terminal in-frame stop. Translation of this mutant mRNA would produce a protein lacking 32 amino acids and expressing 4 altered residues at its new C terminus. CEM-C7.R3 harbored a non-sense mutation (Q710X) in exon 8, and its mRNA would be translated into a protein lacking 67 residues. Only CEM-C7.R4 cells were devoid of mutations in the coding region of the L753F negative allele. These data suggest that, in the CCRF-CEM acute-lymphatic-leukemia model, mutations in the GR-gene coding region represent one, but not the only, cause of GC resistance.

Role of 7,8-dihydroneopterin in T-cell apoptosis and HTLV-1 transcription in vitro

Adult T-cell leukemia is associated with high levels of neopterin, released in large amounts from human macrophages upon stimulation with interferon-gamma. Recent data suggested a potential role of neopterin-derivatives in oxygen radical-mediated processes, and evidence accumulates that oxidative stress is involved in the pathogenesis of viral diseases. We now report that increased concentrations of 7,8-dihydroneopterin may lead to enhanced apoptosis and disturbance of the redox-balance of human leukemic Jurkat T cells. Additionally, we demonstrate that 7,8-dihydroneopterin and hydrogen peroxide activate the type 1 human T-cell leukemia virus (HTLV-1) long terminal repeat (LTR). Furthermore, we found that the activity of the HTLV-1 transactivator protein Tax is amplified by an elevated concentration of 7,8-dihydroneopterin. Tax did not significantly augment 7,8-dihydroneopterin mediated apoptosis. Based on our data we propose that 7,8-dihydroneopterin may be involved in the progression to higher stages of HTLV-1 associated disease.

Human renal-cell carcinoma tissue contains dendritic cells

Immune surveillance of cancer requires antigen-presenting cells which activate T cells specific for tumor-associated antigens. We show here that substantial numbers of dendritic cells, which are the most potent antigen-presenting cells, emigrate from renal-tumor explants in organ culture. Tumor-derived dendritic cells presented with all characteristics of mature dendritic cells. Dendritic cells could be identified by typical cytoplasmic projections (=veils). They expressed high levels of MHC products and of the co-stimulator CD86 (B7-2). Dendritic cells expressed the CD45RO isoform but not CD45RA. The most important point was that up to 9% of the emigrating leukocytes expressed the CD83 antigen, a specific marker for mature dendritic cells. CD83+ cells were approximately 40-fold enriched in the tumor tissue as compared to the peripheral blood. In contrast to cultured blood dendritic cells, tumor-emigrant dendritic cells had a reduced potential to capture soluble antigen, as shown by the exclusion of fluoresceinated Dextran molecules. Finally, in mixed leukocyte reactions, tumor-derived dendritic cells were able to stimulate naive T cells from cord blood, which is a unique feature of dendritic cells. This study demonstrates that genuine dendritic cells reside in or infiltrate renal-cell carcinoma tissue. The failure of patients with renal-cell carcinoma to mount an anti-tumor immune response despite the presence of professional antigen-presenting cells in the tumor tissue suggests that tumor-associated dendritic cells are suppressed in situ, in a similar way to that described for tumor-infiltrating lymphocytes.

Evidence for a graft-versus-tumor effect in a patient treated with marrow ablative chemotherapy and allogeneic bone marrow transplantation for breast cancer

Graft-versus-leukemia (GvL) has been shown to be an important immune-mediated antitumor effect in hematologic malignancies. It is still unknown whether such an immunemediated antitumor effect has clinical implications in patients with solid tumors. A 32-year-old woman with inflammatory breast cancer received a bone marrow transplant (BMT) from her HLA-identical sibling. During graft-versus-host disease (GvHD) cytotoxic T lymphocytes were grown and tested in a chromium-release assay against B and T lymphocytes of the patient and donor and against a panel of breast cancer cell lines. Resolution of liver metastases was observed simultaneously with clinical GvHD in the first weeks after transplant. In addition, minor histocompatibility antigen (MiHA)-specific and major histocompatibility complex (MHC) class I antigen-restricted cytotoxic T lymphocytes recognizing breast carcinoma target cells were isolated from the blood of the patient. Pretreatment of such target cells with tumor necrosis factor (TNF)-alpha but not with interferon (IFN)-alpha or IFN-gamma increased susceptibility of these cells to lysis by cytotoxic T lymphocytes. Clinical course and in vitro results suggest that a graft-versus-tumor (GvT) effect might exist after allogeneic BMT for breast cancer. However, clinical experience on a larger scale would be required to determine the clinical efficacy of GvT effects in patients with solid tumors.

Phenotypic and functional characterization of CD11c+ dendritic cell population in mouse Peyer's patches

The antigen-presenting cell system in the gastrointestinal tract, one of three main sites (skin and lung being the others) of primary antigen contact, is poorly understood. Our study focused on dendritic cells (DC) as possible candidates for antigen uptake, processing and presentation in mucosal inductive sites, such as Peyer's patches (PP). To investigate the morphology, immunophenotype and stimulatory activity of intestinal DC, a procedure was developed to obtain a cell population by using collagenase digestion of PP, density centrifugation and cell sorting on the basis of CD11c expression. The resultant low-density cell fraction consisted of a nonadherent cell population expressing different intensities of CD11c that could at least be characterized by typical DC morphology (e.g. abundant cytoplasma with veil-like cytoplasmatic dendrites, irregularly shaped nuclei, multivesicular and multilamellar bodies), constitutive levels of surface MHC class II, the presence of macrophage-specific markers, such as F4/80, Mac-I and Fc receptors, respectively, on subpopulations of CD11c+ sorted cells and expression of adhesion and co-stimulatory receptors like ICAM-1 and CD44. The capability of this low-density CD11c+ fraction to stimulate T cell responses was demonstrated in primary allogeneic mixed-lymphocyte reactions (MLR). Herein, we show that the freshly isolated CD11c+ cells showed weak accessory function, but develop this capacity following short-term culture in vitro in the presence of granulocyte/macrophage colony-stimulating factor. Although the nature and functional capacity of the isolated CD11c+ needs further clarification, these preliminary results describing phenotype and accessory function provide some evidence that these cells isolated from the PP may be immature forms of DC and play a crucial role as antigen-presenting cells with important implications for understanding the complex network regulating intestinal antigen uptake, processing and presentation.

Preparation and characterization of poly-(D,L-lactide-co-glycolide) and poly-(L-lactic acid) microspheres with entrapped pneumotropic bacterial antigens

Poly-(lactide-co-glycolide) microspheres with entrapped antigen have shown considerable promise as controlled release vaccines. To enhance the immunomodulatory effect of LW 50020, a bacterial lysate of seven common respiratory pathogens used perorally as an immunomodulator, we prepared poly-(D,L-lactide-co-glycolide) (PLG) and poly-(L-lactic acid) (PLA) microspheres with entrapped immunomodulator by solvent evaporation or solvent extraction double emulsion techniques. Physical properties, such as particle size, LW 50020 entrapment rate, antigen release patterns and morphological characteristics were investigated. All preparations displayed a high degree of antigen loading up to 95%, whereas size, surface morphology and antigen release patterns were significantly influenced by the method of preparation and the polymer components used. Solvent evaporation microspheres are porous particles from 0.8 micron to 2.0 microns in diameter, that show a rapid antigen release for PLG, and a moderate antigen release for PLA microspheres within 33 days. Solvent extraction microspheres have proven to be particles from 1.1 microns to 5.0 microns in diameter showing a smooth surface and a medium antigen release rate over 33 days. SDS-PAGE and immunoblotting of extracted antigen confirmed that the molecular weight and antigenicity of the immunomodulator remained unaltered by the entrapment procedure.

Comparison of low density lipoprotein uptake by different human lymphocyte subsets: a new method using double-fluorescence staining

A method to determine low density lipoprotein (LDL) uptake of distinct lymphocyte subpopulations was developed using fluorescent LDL and subsequent staining of lymphocyte subsets with biotinylated monoclonal antibodies plus streptavidin-CyChrome. LDL uptake was detected on a single cell level and semiquantified by FACS analysis. This method allows comparison of defined lymphocyte subsets from different individuals and excludes the falsifying influence of individual differences in subset distribution, which may occur in studies on total peripheral blood lymphocytes (PBL). Investigation of total PBL and lymphocyte subsets of 20 healthy volunteers (8 male, 12 female) showed the following. i) Different lymphocyte subsets exhibited highly significant differences in LDL uptake, with NK cells (CD16) showing a higher uptake than T (CD3) and B cells (CD19); CD8-positive cells exhibited higher values than CD4-positive cells. ii) These differences are due to specific, LDL-receptor (LDL-R)-mediated LDL uptake. iii) Inter-individual differences in LDL uptake are reflected on all lymphocyte subsets.

Inhibitory effects of the nucleoside analogue gemcitabine on prostatic carcinoma cells

Gemcitabine (2',2'difluoro-2'deoxycytidine, dFdC) is a synthetic antimetabolite of the cellular pyrimidine nucleotide metabolism. In a first series of in vitro experiments, the drug showed a strong effect on the proliferation and colony formation of the human androgen-sensitive tumor cell line LNCaP and the androgen-insensitive cell lines PC-3 and DU-145. Maximal inhibition occurred at a dFdC concentration as low as 30 nM. In contrast to the cell lines which were derived from metastatic lesions of prostate cancer patients, no inhibitory effects were found in normal primary prostatic epithelial cells at concentrations up to 100 nM. The effect of gemcitabine was reversed by co-administration of 10-100 microM of its natural analogue deoxycytidine. In view of a future clinical application of this anti-tumor drug in advanced prostatic carcinoma, we have compared the effect of gemcitabine on prostatic tumor cells with that on bone marrow granulopoietic-macrophage progenitor cells, because neutropenia is a common side effect of gemcitabine treatment. The time course of action on the two kinds of cells was markedly different. Colony formation of tumor cells was inhibited by two thirds at a gemcitabine concentration of about 3.5 nM. The same effect on granulopoietic-macrophagic progenitor cells required a concentration of 9 nM. Co-administration of deoxycytidine to gemcitabine-treated tumor cell cultures completely antagonized the effect of gemcitabine whereas addition of deoxycytidine after 48 hr of gemcitabine treatment could not prevent gemcitabine action on the tumor cells. In contrast, more than half of the granulopoietic-macrophagic progenitor cells could still be rescued by deoxycytidine administration after 48 hr. These findings and the marked difference in the susceptibility of neoplastic and normal prostatic cells suggest that gemcitabine is a promising substance which should be further evaluated as to its efficacy in the treatment of advanced prostatic carcinoma.

Dendritic antigen-presenting cells from the peripheral blood of renal-cell-carcinoma patients

Dendritic cells are considered to be the initiators of immune responses, including those directed against tumors. Clinical research on dendritic cells was long hampered by the limited availability of these cells. The recent identification of cytokine combinations that mobilize dendritic cells with potent antigen-presenting cell function from peripheral blood represented a major progress. We show in this study that substantial numbers of dendritic cells can be obtained from the peripheral blood of patients with renal-cell carcinoma. The procedure requires a relatively small blood sample (40 ml) and avoids both priming of the patient with granulocyte-colony stimulating factor and leukapheresis. Approximately 2 to 8 million cells with the characteristics of dendritic cells could be obtained: phase-contrast microscopy revealed the typical cytoplasmic processes or veils; phenotypic analysis confirmed expression of dendritic-cell-associated molecules, including MHC class II, CD1a, CD4, ICAM-1 (CD54), LFA-3 (CD58), B7-1 (CD80) and B7-2 (CD86), and absence of T-cell, B-cell and monocyte markers; in addition, these cells rapidly attached to and migrated on collagen-type-1-coated surfaces. Interestingly, attachment was accompanied by acquisition of the CD14 antigen; functionally, cultured dendritic cells proved to be very potent co-stimulators of the phytohemagglutinin-induced proliferation of autologous tumor-infiltrating lymphocytes. The reproducible growth of functional dendritic cells from cancer patients is encouraging for the design of immunotherapy protocols.

Altered switch in lipid composition during T-cell blast transformation in the healthy elderly

Decreased mitogen responsiveness of lymphocytes during aging correlates inversely with membrane microviscosity, which reflects an altered lipid composition. Therefore, we addressed the question, whether age-related alterations of lipid metabolism affect the switch in lipid composition during formation of blasts. Membrane lipids and fatty acids of peripheral blood lymphocytes from SENIEUR protocol compatible ("healthy") elderly donors (66-77 yr) and young controls (18-30 yr) were quantified after incubation with or without the mitogen phytohaemagglutinin. The blastic change in membrane lipid composition was different for young controls with respect to cholesterol, phosphatidylethanolamine, total phospholipids, as well as several fatty acids. Moreover, the age-related alterations in the switch of membrane lipids and fatty acids were significantly correlated with a decreased mitogen response. Thus, the alterations in membrane reorganization during blast formation of lymphocytes from the elderly point to a disturbed cellular lipid homeostasis with possible impact on the age-related reduction in immune function.

Reference intervals for human peripheral blood lymphocyte subpopulations from 'healthy' young and aged subjects

Some lymphocyte subpopulations change during aging but age-related reference limits from a healthy reference population are still lacking. In this study, we compiled 90% reference intervals for commonly determined lymphocyte subpopulations in 'healthy' (Senieur-compatible) young (20-32 years) and elderly (65-74 years) subjects. The most striking age-related changes included increases in HLA-DR+ T lymphocytes, and the shift in the expression of CD45 isoforms from the CD45RA+CD45RO-to the CD45RA-CD45RO+ subset. Both age-related alterations occurred in the CD4+ as well as in the CD8+ subpopulations and most of them were present in the relative and absolute number of lymphocyte subsets. We compare our data with those from previous investigations on lymphocyte subpopulations from the elderly and comment on useful presentation of reference values.

Tumor-infiltrating T lymphocytes from renal-cell carcinoma express B7-1 (CD80): T-cell expansion by T-T cell co-stimulation

B7-1 (CD80) provides co-stimulation for T-cell activation by interacting with CD28 or CTLA4. Here we demonstrate the expression of B7-1 in freshly isolated and cultured lymphocytes from renal-cell carcinoma. In fresh preparations of lymphocytes infiltrating renal-cell-carcinoma tissue, B7-1 mRNA could readily be detected by reverse transcription PCR, and 2-color flow-cytometry analysis revealed substantial B7-1 expression on T cells from these isolates. As expected, tumor-derived T cells also expressed CD28, the B7 receptor. While B7-1 expression of tumor-derived T cells was maintained during culture in interleukin-2-supplemented medium, CD28 expression was further enhanced. We also show that B7-1 is functionally involved in T-cell expansion: anti-B7-1 MAb inhibited the PHA-induced proliferation of tumor-derived B7-1+ T cells (35%) in the absence of exogenous antigen-presenting cells, indicating that B7-1 mediates T-T cell co-stimulation (self-co-stimulation). Our data demonstrate that T cells infiltrating renal-cell carcinoma express B7-1, and that mutual co-stimulation via the B7-1/CD28 pathway contributes to the interleukin-2-driven expansion of tumor-derived T cells in vitro. The frequency of B7-1+ T cells in tumor lesions and the level of B7-1 on these cells may determine the time course of T-cell expansion in vivo. Self-co-stimulation, however, might also represent one mechanism leading to the state of suppression or anergy characteristic of tumor-infiltrating lymphocytes.

Effect of neopterin and 7,8-dihydroneopterin on tumor necrosis factor-alpha induced programmed cell death

Tumor necrosis factor-alpha and the formation of reactive oxygen intermediates are central mediators of apoptosis. Recent data indicated a role of neopterin and 7,8-dihydroneopterin in oxygen radical mediated processes. We have therefore investigated the effect of neopterin-derivatives on TNF alpha induced apoptosis of the monocyte-like cell line U937. At an elevated concentration 7,8-dihydroneopterin was found to superinduce TNF alpha mediated programmed cell death due to the formation of reactive oxygen intermediates. Our results imply that in combination with TNF alpha high concentrations of 7,8-dihydroneopterin enhances apoptosis due to oxidative stress on cells.

Chronic granulomatous disease assessed by single-cell granulocyte oxidative burst activity

Here we report on a case of chronic granulomatous disease (CGD) in a 3-year-old boy who suffered from severe repeated bacterial infections including multiple liver abscesses. The case is of interest because (1) the disease is very rare (it is the first case of CGD diagnosed at the Clinic for Pediatric Medicine, University of Innsbruck), (2) the diagnosis, based on clinical parameters and the nitrobluetetrazolium test was completed and validated by single-cell measurements of respiratory-burst activity of the patient's granulocytes in a fluorescence-activated cell sorter (FACS), and (3) the applied FACS method, adapted in our laboratory, presents one of the most sensitive and reliable methods to evaluate this aspect of disturbed granulocyte function.

HIV-1 gp41 binding proteins and antibodies to gp41 could inhibit enhancement of human Raji cell MHC class I and II expression by gp41

Based on our findings, that HIV-1 soluble gp41 could bind to several proteins on the human, T, B and monocyte cells independently of CD4, we examined the effect of HIV-1 soluble gp41 (sgp41;Env amino acids 539-684) on surface expression of MHC I and II, ICAM-1 and CD21 molecules on human Raji cells. Flow cytometry (FACS) analysis demonstrated that sgp41 could selectively enhance MHC class I and II expression on Raji cells, but did not increase expression of other cell surface antigens, such as, CD21 and CD54 (ICAM-1). Soluble gp41 could also enhance MHC class I and II expression on another human B cell line, Bjab. The sgp41-dependent enhancement of the MHC class I and II expression on Raji cells is time- and dose-dependent. The sgp41 enhancement effect on the MHC antigen expression could be inhibited by the sgp41-binding proteins of 45, 49 and 62 kD (isolated from Raji-lysate) which could inhibit the spg41-binding to Raji cells. Interestingly, this sgp41-dependent enhancement of the MHC class I and II expression could also be inhibited by two mAbs to HIV-1 gp41, but not by a third mAb binding to a different site on gp41. These results demonstrate that HIV-1 sgp41 can selectively enhance the human Raji cell MHC class I and II antigen expression and this enhancement effect could be inhibited by the sgp41-binding proteins and anti-gp41 antibodies, and suggest that the sgp41-dependent enhancement is mediated by its binding to Raji membrane proteins of 45, 49 and 62 kD.

HIV-1 gp41 enhances major histocompatibility complex class I and ICAM-1 expression on H9 and U937 cells

Based on our findings that HIV-1 (human immunodeficiency virus type 1) soluble gp41 (sgp41; amino acids 539-684) bound to human T, B, and monocyte cells and enhanced major histocompatibility complex (MHC) class I and II antigen expression on Raji cells, we examined the effect of HIV-1 sgp41 on the surface expression of MHC I and II, ICAM-1, and CD4 molecules on human H9 and U937 cells. Flow cytometry (FACS) analysis demonstrated that sgp41 selectively enhanced MHC class I expression by about 75% on H9 cells and by about 85% on U937 cells, while the ICAM-1 expression was increased by about 70% only on H9 cells and remained unaltered on U937 cells; other molecules, such as MHC class II and CD4, remained unaltered. By comparison, alpha-, beta-, and omega-interferons, but not gamma-interferon, showed similar effects as sgp41 on the expression of MHC class I and ICAM-1 on H9 and U937 cells. The results suggest that HIV-1 gp41 may have a biological function that is involved in the regulation of human MHC class I and ICAM-1 expression.

Lytic susceptibility of target cells to cytotoxic T cells is determined by their constitutive major histocompatibility complex class I antigen expression and cytokine-induced activation status

Cytotoxic T-cell lines (TCL) were raised in vitro using stimulator cells with a defined major histocompatibility complex (MHC) mismatch and tested in a cytotoxic chromium-release assay against haemopoietic and non-haemopoietic target cells from the original stimulator. Monoclonal antibody (mAb)-blocking experiments and simultaneous determination of MHC class I, class II, lymphocyte function-associated antigen-1 (LFA-1) and intracellular adhesion molecule-1 (ICAM-1) density by quantitative radioimmunometric methods and flow cytometry on target cells demonstrated that lysis was restricted by MHC class I and dependent upon the constitutive MHC class I antigen expression. Measurements showed a high constitutive expression of class I MHC antigens on peripheral blood mononuclear cells (PBMC), but a low one on keratinocytes (K). Also, PBMC were more susceptible to lysis by TCL than K. Interferon-gamma (IFN-gamma) treatment of K resulted in increased MHC class I antigen expression and enhanced lytic susceptibility to TCL. IFN-alpha and tumour necrosis factor-alpha (TNF-alpha) treatment, which did not modulate MHC class I antigen expression on K, did not influence the amount of K lysis either. None of the cytokines tested in this analysis, however, increased the expression of MHC class I, class II, ICAM-1 and LFA-1 on PBMC. Only IFN-gamma pretreatment showed a minimal, statistically significant increase in MHC class I antigen expression. In spite of the minimal effect of IFN-gamma and no effect of IFN-alpha on class I MHC expression, pretreatment of target cells with both cytokines considerably increased their lytic susceptibility. The mechanism of cytokine-induced enhanced lytic susceptibility to TCL was not explained by increased MHC class I, LFA-1 or ICAM-1 expression, since no correlation was found between surface expression of these molecules and lytic susceptibility to TCL. These data demonstrate that: (1) the constitutive density of MHC class I antigens determines the extent of TCL lysis; (2) IFN-gamma, and not IFN-alpha or TNF-alpha controls the amount of K target cell lysis by increasing their MHC class I antigen expression; and (3) IFN-gamma and IFN-alpha control the amount of PBMC target cell lysis by a mechanism independent of MHC class I, ICAM-1 or LFA-1 expression.

HIV-1 gp41 binds to two proteins in cell culture supernatant of human B cell line Raji and monocyte cell line U937

Based on our findings that HIV-1 gp41 can bind independently of CD4 to the human T cell line H9, B cell line Raji and monocytic cell line U937, as well as human peripheral blood mononuclear cells preferentially to B lymphocytes and monocytes, we examined whether soluble protein for HIV-1 gp41 binding exists in the cell culture supernatant of Raji and U937. Using HIV-1 recombinant soluble gp41 (sgp41; Env amino acid 539-684) attached to sepharose beads, the cell culture supernatants of Raji and U937 were absorbed. By SDS-PAGE of sgp41-eluates of these cell culture supernatants three protein bands of 70, 75 and 92kD were stained with Coomassie blue. By Western blot (ligand blot) analysis using sgp41, two protein bands of 70 and 75kD were observed in sgp41-eluates from Raji and U937 cell culture supernatants. These sgp41-eluates could inhibit the sgp41 binding to Raji and U937 cells. Our data indicate that Raji and U937 cells produce two soluble binding proteins for HIV-1 gp41.