Differentiation of human single-positive fetal thymocytes in vitro into IL-4- and/or IFN-{gamma}-producing CD4+ and CD8+ T cells

In this study we have investigated the capacity of human fetalthymocytes to differentiate in vitro into subsets of T cellswith polarized T_h1 or T_h2 cytokine profiles. Stimulation offreshly isolated human fetal thymocytes with anti-CD3 mAb, cross-linkedonto CD32,CD58,CD80-expressing mouse fibroblasts and subsequentculture in the presence of exogenous rIL-2 for 6 days, inducedthe production of both IL-4 and IFN-, which was mainly producedby CD4⁺ single-positive (SP) and CD8⁺ SP cells respectively.Addition of rIL-4 during priming augmented IL-4 production incultures of human fetal thymocytes, which was mainly due toan increased production of IL-4 by CD8SP cells. In contrast,addition of IL-4 to the cultures only slightly enhanced IL-4production and had little effect on frequencies of IL-4-producingCD4SP cells. Both CD4SP and CD8SP cells produced IL-5, IL-10and IL-13 at comparable levels, following priming in the presenceof rIL-4. Priming in the presence of rIL-12 strongly enhancedthe production of IFN- in both CD4SP and CD8SP cells. No correlationbetween expression of CD27, CD30 and CD60, and a particularcytokine profile of differentiated thymocytes could be demonstrated.Together, these results demonstrate the full capacity of fetalhuman thymocytes to differentiate into cytokine-producing Tcells in a priming milieu with appropriate stimulatory moleculesand exogenous cytokines. In addition, CD4SP thymocytes rapidlydifferentiate into polarized T_h2 cells following stimulationin vitro in the absence of exogenous rIL-4.     

Expression of apoptosis-related proteins and morphological changes in a rat tumor model of human small cell lung cancer prior to and after treatment with radiotherapy,carboplatin, or combined treatment

PURPOSE: In order to understand the apoptosis pathway in tumor cells, differences in cell morphology and expression of apoptosis-related proteins induced by radiation and/or chemotherapy, were investigated in a rat double tumor model comparing cisplatin-sensitive and -resistant human small cell lung cancer tumors. METHODS: The cisplatin-sensitive human small cell lung cancer cell line (GLC4) and its cisplatin-resistant subline (GLC4-CDDP) were each injected subcutaneously in a different hind limb of the rat. After 15-17 days, radiation (10 Gy), carboplatin (25 mg/kg, intraperitoneal), combined treatment, or no treatment was administered. In combined treatment, carboplatin was administered 24 h before radiation. Tumors were removed and fixed 72 h after carboplatin or 48 h after radiation. Paraffin-embedded slides were stained with hematoxylin/eosin for morphology. Expression of the apoptosis-related proteins p53, p21, Rb, bcl-2, bax, c-myc, Fas and Fas-L was assessed immunohistochemically. RESULTS: In the GLC4 tumor, carboplatin treatment increased tumor cell size, tumor cell size heterogeneity, and number of apoptotic tumor cells. After radiation and combined treatment, these changes were more pronounced and multinuclear giant cells were observed. In GLC4-CDDP tumors, minimal changes were detected after carboplatin. Following radiation slight increases in tumor cell size, tumor cell size heterogeneity and number of apoptotic tumor cells were observed. No multinuclear giant cells were seen. After combined treatment, GLC4-CDDP showed cellular changes comparable to those in GLC4 cells after radiation or combined treatment, but no giant cells were observed. Untreated, both tumors were equally positive for p53, bax, Fas, Fas-L, c-myc and negative for Rb. Contrary to GLC4, untreated GLC4-CDDP tumors showed no p21 and bcl-2 expression. After combined treatment, an increase in number of bcl-2 positive cells was found in GLC4-CDDP tumors. No p21 was induced in GLC4-CDDP by any treatment modality. In GLC4 tumors, p21 was induced by radiation alone. No further changes in protein expression were induced by any treatment in GLC4 tumors. CONCLUSION: Following therapy, morphological changes in cell size and cell size heterogeneity were more pronounced in GLC4 than in GLC4-CDDP tumors. However, morphological changes in GLC4-CCDP tumors after treatment indicate that carboplatin plus radiotherapy may be effective also in cisplatin resistant tumor cells. An increase in p21 in GLC4 after radiation might facilitate apoptosis. The increase in number of Bcl-2 positive cells after combined treatment and the consistently negative p21 status after any treatment in GLC4-CDDP may protect these tumor cells from apoptosis as a part of their resistance mechanism to cisplatin.     

Phenotypic and functional characterization of human suppressor T-cell clones: II. Activation by Mycobacterium leprae presented by HLA-DR molecules to alpha beta T-cell receptors.

We have been studying human T-cell clones that suppress anti-mycobacterial T-cell responses but not T-cell responses to an unrelated antigen or mitogen. In the present paper we report our studies on the activation requirements of these suppressor-T-cell clones. The suppressor-T-cell clones could proliferate and produce interferon-gamma upon stimulation with Mycobacterium leprae and other mycobacteria but not with unrelated antigens or autologous T cells. Both suppressor and nonsuppressor clones react to a 36-kDa antigen of M. leprae. Thus far, we have not been able to demonstrate whether they see the same or different epitopes. The antigen-driven proliferation of suppressor-T-cell clones was, however, significantly lower than that observed for T-cell clones that did not mediate suppression. The proliferation of suppressor-T-cell clones to M. leprae antigens could be blocked by monoclonal antibodies to HLA-DR, alpha beta T-cell receptor, interleukin-2 receptor, and, in the case of CD4-positive suppressor-T-cell clones, anti-CD4 monoclonal antibodies. DR restriction of the antigen presentation to these suppressor-T-cell clones was shown in mixing experiments using antigen-presenting cells as mononuclear cells from family members and unrelated individuals. These experiments also indicated that apart from regular DR-restriction a hitherto unknown factor may be required for presentation to or activation of suppressor-T-cell clones that is present in the family members and unrelated individuals with the same ethnic and geographic background but absent in DR/Dw-matched healthy Dutch individuals.     

Determination of capillary leakage due to recombinant interleukin-2 by means of noninvasive conductivity measurements

Summary One of the most common side effects of treatment with recombinant interleukin-2 (IL-2) is capillary leakage. Its genesis is not completely understood. The aim of the study was to determine whether capillary leakage can be monitored by means of a non-invasive conductivity technique and to study its starting point. Eight patients with advanced renal cell cancer were studied in a medium care section of the Department of Medical Oncology, University Hospital over 4 days during treatment sessions of continuous, intravenously administered IL-2 (mean dose of 15.6 × 10⁶ IU · m^–2 · day ^–1). The fluid shift from the intravascular to the extra- and intracellular compartments was monitored by means of noninvasive conductivity measurements. Changes in blood volume were calculated from serial erythrocyte counts. The clinical parameters of capillary leakage (oliguria, positive fluid balance, and gain in mass) were recorded. The mean gain in mass was 9% after 4 days of IL-2 treatment. The extracellular fluid volume increased significantly [46 (SD 23.2)%; P < 0.01], whereas the intracellular fluid volume did not change. The increase in blood volume (BV) amounted to 7% (P < 0.05). The decline in albumin concentration was significantly more than the increase in BV [38 (SD 4.3) %; P < 0.01], indicating capillary albumin leakage. The main changes were observed after the 2nd day of treatment. From this study, it is suggested that conductivity measurements are a suitable method to monitor capillary leakage induced by IL-2, and could be used to detect the exact onset and severity of this leakage. The leakage started within the first 24 h of treatment and was detected as a fluid shift from the intravascular to the extracellular space, while the intracellular compartment remained stable. These measurements could be useful during intervention studies with the aim of preventing this adverse effect of IL-2.     

Differential regulation of IL-13 and IL-4 production by human CD8+ and CD4+ Th0, Th1 and Th2 T cell clones and EBV-transformed B cells

In the present study, the requirements and characteristics forthe production of IL-13 by human T cells, T cell clones andB cells were determined and compared with those of IL-4. IL-13was produced by human CD4⁺ and CD8⁺ T lymphocyte subsets isolatedfrom peripheral blood mononuclear cells and by CD4⁺ and CD8⁺T cell clones. CD4⁺ T cell clones belonging to T_h0, T_h1-likeand T_h2-like subsets produced IL-13 following antigen-specificor polyclonal activation. In addition, EBV-transformed B celllines expressed IL-13 mRNA and produced small amounts of IL-13protein. Expression of IL-13 mRNA and production of IL-13 proteinby peripheral blood T cells and T cell clones was induced rapidlyand was relatively long lasting, whereas IL-4 production bythese cells was transient In addition, IL-13 mRNA expressionwas induced by modes of activation that failed to induce IL-4mRNA expression. IL-13 shares many biological activities withIL-4 which Is compatible with the notion that the IL-13 andIL-4 receptors share a common component required for signaltransduction. However, IL-13 lacks the T cell-activating propertiesof IL-4. Here we have shown that this is related to the factthat T cells fall to bind radiolabeled IL-13 and do not expressthe IL-13-speclflc receptor component Taken together, theseresults indicate that the differences In expression and biologicalactivities of IL-4 and IL-13 on T cells may have consequencesfor the relative roles of these cytokines In the immune response.     

Standardization of allergenic extracts of Aspergillus fumigatus. Liberation of IgE-binding components during cultivation

During cultivation of Aspergillus fumigatus a rapid liberation of IgE-binding components was found reaching maximum values during the logarithmic phase of growth (phase I). After a fall in IgE-binding titers during phase II, appearance of additional IgE-binding components was noted during the period of lysis of the microorganism (phase III). These latter allergenic components are different from the phase I IgE-binding components, as was shown by crossed-inhibition studies. The number of precipitating antigenic components was not related with the corresponding IgE-binding titers and showed an increase during all phases of growth. The rapid changes in both IgE- and IgG-binding properties and the discrepancies between precipitating properties and IgE binding are discussed in relation to standardization and quality control of aspergillus extracts.     

Individual differences in the effects of serotonergic anxiolytic drugs on the motivation to self-administer cocaine

Numerous clinical studies have indicated that lifetime anxiety is highly prevalent in drug addicts. In the treatment of drug abuse, dually diagnosed drug addicts may benefit from pharmacological intervention strategies that alleviate the psychiatric symptomatology. We have previously shown that rats with different coping strategies in a stressful environment show strong differences in the motivation to self-administer cocaine. That is, cocaine self-administration under a progressive ratio (PR) schedule of reinforcement was enhanced in high grooming (HG) rats as compared with low grooming (LG) rats. To identify the pharmacological basis of these differences, we tested the acute effects of several anxiolytic drugs on cocaine self-administration in HG and LG rats under a PR schedule of reinforcement. Chlordiazepoxide increased PR responding in both the HG and LG rats, while the selective corticotrophin releasing hormone 1 receptor antagonist R121919 had no effect on cocaine self-administration under the PR schedule. Interestingly, buspirone and fluoxetine decreased PR responding in HG rats only and thereby abolished the individual differences in PR responding between HG and LG rats. In support of the differential effects of the serotonergic drugs on PR responding in HG and LG rats, we found that the in vitro electrically evoked release of [3H]serotonin from mesocorticolimbic brain slices was reduced in the medial prefrontal cortex, substantia nigra and nucleus accumbens core, and increased in the nucleus accumbens shell of HG rats relative to LG rats. These findings show that serotonergic anxiolytics abolish the pre-existing individual differences in cocaine self-administration between HG and LG rats, which show differences in the reactivity of serotonergic neurons. This suggests that the effectiveness of pharmacological interference may depend on the neurochemical and motivational state of the individual.     

Involvement of serotonin in intestinal mastocytopoiesis and inflammation during a Trichinella spiralis infection in mice

The involvement of serotonin in the regulation of intestinal mastocytopoiesis and inflammation has been investigated in mice infected with Trichinella spiralis. Two serotonin antagonists, methysergide and ketanserin, were examined for their ability to interfere with jejunal pathology comprising the influx of mucosal mast cells and other inflammatory cells during an infection with T. spiralis and with worm expulsion. In vitro analysis of the frequency of mast cell precursors in bone marrow, blood, spleen and intestinal tissue suggested that the mucosal mast cell response during a T. spiralis infection is probably due to invasion and local maturation in the gut of mast cell precursors, and may be mediated by T-cell-derived mast cell growth factors. Since both serotonin antagonists inhibited the mucosal mast cell response in T. spiralis-infected mice and diminished the influx of eosinophilic granulocytes, goblet cell hyperplasia, and villous atrophy, it was concluded that during a T. spiralis infection in mice release of serotonin may provide an environment that facilitates the local influx in the gut of inflammatory cells. Since worm expulsion was not affected by the serotonin antagonists, these results suggest that worm expulsion can occur without a mast cell and or eosinophilic granulocyte influx. The role of serotonin release by as yet unidentified serotonin-containing cells in the gut in relation with T cell regulation is discussed.     

A “Stopper” mutant of Neurospora crassa containing two populations of aberrant mitochondrial DNA

Summary [E35], an extranuclear mutant of Neurospora crassa has all the phenotypic characteristics of the stopper mutants (De Vries et al. 1980). In the present work, the mitochondrial DNA as well as the mitochondrial translation products are characterized further. The primary mutational event appears to have been the deletion of about 4 kbp from the wild-type genome. Moreover, after prolonged vegetative growth the mutant accumulates an 8-m circular mtDNA, which was demonstrated both by electronmicroscopy and by restriction enzyme analysis. Hence, the mutant contains two populations of aberrant mitochondrial DNA, the smaller of which is an amplification of the rRNA-tRNA part of the larger. We propose that the primary deletion has generated a signal in the larger DNA which can cause premature termination of replication at the deletion site, and subsequent circularization of the unfinished daughter molecule. Finally, the deleted part may contain a determinant for synthesis of a protein of 11 kDal. The function of this protein, which is not a subunit of the F₀ ATPase, is not yet known.Abbreviations (k)bp (kilo)basepairs - kDal kilodalton - mt mitochondrial