Production and characterization of the exopolysaccharides produced by Agaricus brasiliensis in submerged fermentation

The aim of the work was to study the production of the exopolysaccharides by Agaricus brasiliensis and the isolation of exopolysaccharides (EPSs) with biological effects. A brasiliensis LPB03 was cultured in submerged fermentation in a medium containing glucose, yeast extract, hydrolyzed soybean protein, and salts (pH 6.1) at 29 degrees C and 120 rpm for 144 h. The maximum biomass and EPS yield was 7.80 +/- 0.01 and 1,430.70 +/- 26.75 mg/L, respectively. To isolate the produced EPSs, two methods were compared: (1) with alcohol precipitation and (2) treatment with tricloroacetic acid (TCA), followed by alcohol precipitation. The use of TCA facilitated the purification of the EPS, reducing the amount of the contaminant soy proteins. For monosaccharide identification, the EPSs were hydrolyzed, derivatized to alditol acetates, and analyzed by gas chromatography (GC) and GC-mass spectrometry, which showed the presence (in molar percentage) of mannose (58.7), galactose (21.4), and glucose (13.1) as major sugars, with lower amounts of rhamnose (3.9) and xylose (2.8). Scanning electron microscopy was used to observe the morphological structure of the EPS. The experiments in vivo including EPS in the mice diet during 8 weeks indicated the hipocholesteremic and hypoglycemic effects.

Comparison of new different assay systems for thyrotropin receptor antibodies with reference to thyroid-stimulating antibodies and thyroid stimulation-blocking antibodies in Graves' disease

The aim of our study was to evaluate the diagnostic sensitivity of the new thyrotropin receptor antibody (TRAb) assays (Cosmic TRAb CT, ELISA and Yamasa DYNOtest TRAb). TRAb was positive in 43 of 44 (97.7%) untreated patients with Graves' disease by both TRAb CT and/or ELISA and NYNOtest TRAb. Thus the new TRAb assays were clearly more sensitive than the conventional assay (positivity: 85%). There was a strong positive correlation between the data obtained in TRAb CT and/or ELISA and those obtained in DYNOtest TRAb (r = 0.942, p < 0.0001). There was a significant correlation between the new TRAb and TSAb (r = 0.696, p < 0.0001). Although there was a significant correlation between the new TRAb and thyroid stimulation-blocking antibody (TSBAb), the correlation coefficient was low (r = 0.605, p < 0.0001). The increased sensitivity of the new TRAb assays for Graves' disease provides an advantage over conventional assay.

Increased susceptibility to airway responses in CD40-deficient mice

The interaction between CD40 and its ligand (CD154) is crucial for IL-12 production and effective humoral immunity such as IgE production. Although the interaction seems to play a crucial role in asthmatic inflammation, previous studies investigating the role of the CD40 and CD154 interaction in experimental animal models of asthma are complicated due to multistep reactions in developing asthma. Here, in order to investigate the role of CD40 in the effector phase in the development of airway responses, we used CD40-deficient mice backcrossed with mice transgenic for an ovalbumin (OVA)-specific TCR (TCRtg). Using intranasal OVA administration followed by aerosol inhalation of OVA, greater airway hyperreactivity and eosinophilia in bronchoalveolar lavage fluid (BALF) were observed in CD40-deficient mice backcrossed with TCRtg mice (CD40-/-/ TCRtg mice), compared with control littermates (CD40+/+/ TCRtg mice). CD4+ helper T cell subset analysis of lung draining lymph nodes revealed that the Th1 component was significantly decreased in CD40-/-/ TCRtg mice. Airway hyperreactivity and airway eosinophilia significantly correlated with the predomination of Th2 cells. Cytokine measurements in BALF also showed decreased IL-12 and the predominance of Th2 cells in CD40-/-/ TCRtg mice. These results suggest that CD40 may play a protective role in developing asthma in the phase after establishing specific memory T cells through the regulation of the balance between Th1 and Th2 cells presumably via induction of IL-12.

Lactobacillus casei strain Shirota suppresses serum immunoglobulin E and immunoglobulin G1 responses and systemic anaphylaxis in a food allergy model

BACKGROUND

Our previous study using allergen-sensitized murine splenocyte cultures has shown that Lactobacillus casei strain Shirota (LcS), a lactic acid bacterium widely used as a starter for fermented milk products, suppresses IgE production through promoting a dominant Th1-type response mediated by IL-12 induction.

OBJECTIVE

We tried to evaluate the ability of LcS to suppress both IgE response and allergic reactions in vivo using a food allergy model with ovalbumin-specific T cell receptor transgenic (OVA-TCR-Tg) mice.

METHODS

The ability of heat-killed LcS to induce IL-12 in serum was tested. OVA-TCR-Tg mice were fed a diet containing OVA for 4 weeks and injected with LcS intraperitoneally three times in the first week of this period. Cytokine and antibody secretion by splenocytes, and serum IgE and IgG1 responses were examined. The inhibitory effect of LcS on systemic anaphylaxis induced by intravenous challenge of OVA-fed OVA-TCR-Tg mice with OVA was also tested.

RESULTS

Intraperitoneal injection of LcS induced an IL-12 response in the serum of OVA-TCR-Tg mice. In the food allergy model, LcS administration skewed the pattern of cytokine production by splenocytes toward Th1 dominance, and suppressed IgE and IgG1 secretion by splenocytes. The ability of LcS to modulate cytokine production was blocked by anti-IL-12 antibody treatment. LcS also inhibited serum OVA-specific IgE and IgG1 responses and diminished systemic anaphylaxis.

CONCLUSION

LcS administration suppresses IgE and IgG1 responses and systemic allergic reactions in a food allergy model, suggesting a possible use of this lactic acid bacterium in preventing food allergy.

CD4 T cells monospecific to ovalbumin produced by Escherichia coli can induce colitis upon transfer to BALB/c and SCID mice

Although some animal models suggest an involvement of CD4 T cells reactive to luminal microbial antigen(s) for the pathogenesis of inflammatory bowel diseases (IBD), direct linkage between microflora-driven clonal expansion of CD4 T cells and the development of colitis has not been well studied. Here, BALB/c and SCID mice were given CD4 T cells purified from Rag-2(-/-) mice crossed to transgenic mice expressing TCR specific to ovalbumin (OVA) then administered with antibiotic-resistant Escherichia coli producing OVA (ECOVA) or LacZ (ECLacZ) via the rectum. The ECOVA-inoculated BALB/c and SCID mice developed a subacute colitis with microscopic features of distortion of crypt architecture, loss of goblet cells, and focal infiltration by mononuclear cells in the lamina propria (LP) and submucosa. Expanding OVA-specific CD4 T cells were detected in colonic follicles of mice with ECOVA. Early in colitis, OVA-specific CD4 T cells producing IFN-gamma predominate in the LP of the colon, which was followed by an emergence of OVA-specific CD4 T cells producing IL-4 and IL-10 at a later time point. Co-transfer of an IL-10-secreting OVA-specific CD4 T cell line prevented colitis. Thus, an expansion of CD4 T cells monospecific to OVA, an antigen non-cross-reactive to colonic tissue, can mediate both induction and inhibition of the colitis which was associated with hyperplasia of lymph follicles.

p53 Homologue p63 represses epidermal growth factor receptor expression

Tumor suppressor p53 has been shown to transactivate epidermal growth factor receptor (EGFR) expression through binding to a putative p53 responsive element in the EGFR promoter between nucleotides -265 and -239 (EGFRp53RE). Isotypes of p63 gene products, recently identified as p53 relatives, have a similar function to transactivate several p53 target gene promoters. However, our results indicate that TAp63gamma has a very low ability to bind to the EGFRp53RE and surprisingly represses both basal EGFR promoter activity and endogenous EGFR expression. Transient transfection assays show that the EGFR promoter region between -348 and -293, containing two Sp1 sites, is crucial for the repression of the EGFR expression by TAp63gamma. Mutations in these Sp1 sites in the reporter constructs result in loss of the TAp63gamma repression effect. We further show that TAp63gamma directly interacts with Sp1 by immunoprecipitation analysis and that TAp63gamma impairs Sp1 binding to the target DNA site in electrophoretic mobility shift assays. These results suggest that TAp63gamma is involved in the regulation of the EGFR gene expression through interactions with basal transcription factors.

Limited effect of chromatin remodeling on D(beta)-to-J(beta) recombination in CD4+CD8+ thymocyte: implications for a new aspect in the regulation of TCR beta gene recombination

We have generated mutant mice in which TCR beta chain enhancer (E(beta)) was replaced with the TCR alpha chain enhancer (E(alpha)). Using this mouse model, we analyzed (i) recombination status of the TCR beta chain genes after functional V(D)J rearrangements occurred in the first allele during double-negative (DN)-to-double-positive (DP) transition and (ii) involvement of E(beta) for the expression of rearranged TCR beta chain genes. Our data show that E(alpha) substituted for E(beta) function to express a similar extent of TCR beta chains exactly at the same time as did E(beta) (CD25+CD44- DN stage), although the proportion of TCR beta+ cells at this stage was low in mutant mice. At the DP stage, germline transcription and histone acetylation of D(beta)-J(beta) loci were detectable at a high degree in both mutant and wild-type mice. However, DP cells in mutant mice retained the germline D(beta)-J(beta) configuration at a higher frequency than that of wild-type mice, whereas both DP cells expressed TCR beta chains to a similar extent. These data suggest that chromatin opening has a limited impact on D(beta)-to-J(beta) recombination at the DP stage and that E(alpha) is functionally equivalent to E(beta) in promoting expression of functionally rearranged TCR beta chain genes through DN-to-DP transition.

[Implication on thyroid function tests]

We tried to investigate the present problems, concerning the reference individual and interval in thyroid function tests and find the solutions for them. We are now using healthy adults for the reference individual and interval. Recently, we found the sex-difference and age-related changes for reference individual and interval in free T3 measurement. We raised the questions on whether there are any sex-differences and/or age-related changes or not. Surprisingly, there were almost no detailed data about them especially in Japan. Therefore, we examined the Europe data, and found out some kind of sex-differences and age-related changes. We propose the following examinations using many Japanese population in order to provide a precise and proper reference individual and interval: 1. Whether there are any sex-difference in thyroid function tests? 2. Whether there are age-related change in thyroid function tests, for instance, simply dividing population into the immature, adult and the aged?

Ciliary neurotrophic factor, a gp130 cytokine, regulates preovulatory surges of luteinizing hormone and prolactin in the rat

Ciliary neurotropic factor (CNTF) is a neuroregulatory cytokine belonging to the interleukin-6 type cytokine superfamily. Although a few studies have reported a facilitatory action of CNTF on the reproductive axis in rodents, information along this line is still very limited. In this study, we examined a possible role of CNTF in the generation of ovarian steroid-induced luteinizing hormone (LH) and prolactin (PRL) surges in the rat, a crucial physiological event in mammalian reproduction. Experiments were performed on both normally-fed and 3-day-fasted rats, ovariectomized and primed with estradiol and progesterone. Blood was collected every 30 min between 11:00 and 18:00 h, to measure LH and PRL. Drugs were given intracerebroventricularly at 11:00 h. Compared to control serum, undiluted as well as threefold dilutions of anti-CNTF serum caused partial but significant suppression of LH surges. Both concentrations of the antibody also delayed the onset of PRL surge to a comparable degree. Fasted rats did not exhibit significant surges of the hormones, while 0.3 and 1.0 nmol, but not 0.1 nmol, recombinant human CNTF led to a dose-dependent recovery of both LH and PRL surges. These results demonstrate for the first time a significant role of CNTF in the generation of preovulatory LH and PRL surges in the rat. CNTF may thus be another humoral signal linking nutrition and reproductive function.

Overexpression of AML1 transcription factor drives thymocytes into the CD8 single-positive lineage

To understand the gene regulation involved in the development of single-positive (SP) thymocytes, we generated transgenic mice in which the AML1 transcription factor is overexpressed. In these mice the number of CD8 SP thymocytes was greatly increased, and this continued to be true even when MHC class I was absent. This promotion to the CD8 SP lineage was not, however, observed when both class I and class II were absent. Furthermore, even thymocytes carrying MHC class II-restricted TCR differentiated into the CD8 SP lineage when AML1 was overexpressed. The selected CD8 SP cells were, however, unable to mature, as judged by the expression level of heat-stable Ag. Thus, overexpression of AML1 is able to skew class II-restricted thymocytes into the CD8 SP lineage, but not to drive the maturation of resulting selected CD8 SP cells.

Identification of a novel retrovirus long terminal repeat (LTR) that is targeted by p51A (TAp63gamma) and selective dominant-negative activity of p73L (DeltaNp63alpha) toward p53-responsive promoter activities

The p51/p73L/p63/p40 gene, recently identified as a p53 homolog, encodes two major isoforms, p51A and p73L, which are suggested to have similar functions synonymous with p53 and dominant-negative activity toward both p53 and p51A, respectively. We have cloned a high affinity genomic fragment bound to p51A that was assigned to be a novel retrovirus long terminal repeat. Strikingly, this fragment was found to bind to both p53 and p73L with similar affinity to p51A. Additional demonstration with known p53 response elements suggested that DNA-binding profiles of p51A and p73L were very similar but were distinct from that of p53. Consistent with this novel finding, transient cotransfection experiments in mammalian cells suggested that p73L, when it was expressed at a low level, selectively suppressed p53-dependent transactivation of p21-luc and mdm2-luc but not of cyclinG-luc and bax-luc reporters. These data raise the possibility that p73L differentially modulates the p53 function according to the distinct DNA-binding affinity between these two proteins.

Surface molecules essential for positive selection are retained but interfered in thymic epithelial cells after monolayer culture

It has been reported that the three-dimensional structure of thymic epithelial cells (TECs) is responsible for thymic positive selection but that this ability disappears when TECs are cultured in monolayer. These results have supported the hypothesis that certain TEC-specific molecules are extinguished during monolayer culture. In this study, using MHC class II-restricted T-cell receptor transgenic mice, we demonstrated that preselected CD4(+)8(+) (DP) thymocytes were inhibited from developing into CD4(+)8(-) (CD4SP) cells in reaggregate thymus organ culture with monolayer-cultured TECs, but this inhibition was removed when TECs were cultured in monolayer with protein synthesis inhibitor or when the cultured TECs were treated with fixative. These results seem to be inconsistent with the previous hypothesis and indicate that monolayer culture allows TECs to retain the surface molecules necessary for positive selection but interferes with their function, which must be sustained for three dimensional structure.

Transcriptional dysregulation of the p73L / p63 / p51 / p40 / KET gene in human squamous cell carcinomas: expression of Delta Np73L, a novel dominant-negative isoform, and loss of expression of the potential tumour suppressor p51

We have recently identified a second p53 -related p73L gene, also referred to as p63 / p51 / p40 / KET gene, which encodes the 2 major isoforms p73L and p51 resulting from different exon usage at their amino terminal regions. Although p73L and p51 are suspected to play oncogenic and tumour suppressive roles in mammalian cells, respectively, no evidence of linkage between the expression of these isoforms and human cancers has been reported so far. In this study, we first investigated the expression profile of p51 and p73L in various human tumour cell lines and found that a novel isoform, termed DeltaNp73L, was predominantly expressed in squamous cell carcinomas. The expression profile of DeltaNp73L/p73L/p51 in primary human skin cancer specimens showed that the expression of p51 was frequently lost (62%) but was detected in all normal skin samples. In p51-expressing skin cancers, DeltaNp73L expression was associated at a high frequency (75%) though it was not detected in normal skin tissues. Transient co-transfection data indicate the possibility that DeltaNp73L can inhibit p53-, and more preferentially, p51-mediated transactivation. These data suggest that the loss of expression of p51 and/or the expression of DeltaNp73L might contribute to the pathogenesis of human squamous cell carcinomas.

Radioimmunoassay for somatostatin receptor type 2

OBJECTIVE

To develop radioimmunoassay for somatostatin receptor type 2 (SSTR2) and search for its presence in certain rat tissues.

METHODS

Anti-SSTR2 antiserum has been raised in New Zealand white rabbits immunized with a conjugate of synthetic SSTR2 with bovine serum albumin. Radioiodination of SSTR2 was performed by chloramin T method followed by purification of radioiodinated material on Sephadex G-25 column.

RESULTS

The obtained antibody did not crossreact with SSTR1, SSTR3, SSTR4, SSTR5, hypothalamic hormones, pituitary hormones, neuropeptides or gut hormones. The assay was performed with a double antibody system. SSTR2 was extracted from the tissues with acid acetone. The dilution curve of acid acetone-extracts of rat hypothalamus in the radioimmunoassay system was parallel to the standard curve. The recovery of tissue SSTR2 was about 89 %, and the intra-assay and inter-assay variations were 4.9 % and 7.8 %, respectively. SSTR2 was found in the hypothalamus, cerebrum, cerebellum, pituitary, stomach and testis.

CONCLUSIONS

These data suggest that this assay system is suitable for the estimation of SSTR2 in the tissues.

Immune tolerance induced by polyethylene glycol-conjugate of protein antigen: clonal deletion of antigen-specific Th-cells in the thymus

Polyethylene glycol (PEG) conjugates of protein antigens induce antigen-specific immune tolerance of helper T (Th)-cells. However, the mechanism of this Th-cell tolerance has remained unelucidated. Using transgenic mice with ovalbumin (OVA)-specific T-cell receptor (TCR) genes, we examined the response of OVA-specific Th-cells towards tolerogenic PEG-conjugate of OVA in vitro and in vivo. When stimulated with PEG--OVA in vitro, transgenic OVA-specific Th-cells proliferated and produced interleukin 2, the levels of which were comparable to those induced by unmodified OVA. In contrast, PEG--OVA administered into the circulation of transgenic mice induced unresponsiveness in peripheral OVA-specific Th-cells. Moreover, in the thymus of these transgenic mice, the frequency of immature CD4+CD8+ (double positive) thymocytes was reduced. A similar phenomenon was not observed in transgenic mice treated with unmodified OVA. As autoreactive T-cells are known to be clonally deleted at the immature double positive stage in the thymus. Th-cell tolerance induced by PEG--protein antigens is at least in part mediated by central tolerance in the thymus, and is likely caused by the markedly enhanced stability of PEG--protein conjugates in the circulatory system.

Increased T cell autoreactivity in the absence of CD40-CD40 ligand interactions: a role of CD40 in regulatory T cell development

Mutations in the CD40 ligand (CD40L) gene lead to X-linked immunodeficiency with hyper-IgM, which is often associated with autoimmune diseases. To determine the contribution of defective CD40-CD40L interactions to T cell autoreactivity, we reconstituted CD40-CD40L interactions by transferring T cells from CD40-deficient mice to syngenic athymic nude mice and assessed autoimmunity. T cells from CD40-deficient mice triggered autoimmune diseases accompanied with elevations of various autoantibodies, while those from wild-type mice did not. In CD40-deficient mice, the CD25(+) CD45RB(low) CD4(+) subpopulation which regulates T cell autoreactivity was markedly reduced. CD40-deficient APCs failed to induce T regulatory cells 1 producing high levels of an inhibitory cytokine, IL-10 in vitro. Furthermore, autoimmune development was inhibited when T cells from CD40-deficient mice were cotransferred with CD45RB(low) CD4(+) T cells from wild-type mice or with T regulatory cells 1 induced on CD40-expressing APCs. Collectively, our results indicate that CD40-CD40L interactions contribute to negative regulation of T cell autoreactivity and that defective interactions can lead to autoimmunity.

Diminution of the AML1 transcription factor function causes differential effects on the fates of CD4 and CD8 single-positive T cells

In the thymic cortex, T lymphocytes are positively selected to survive and committed either to the CD4 single-positive (SP) or the CD8 SP lineage. The SP cells then pass through a step of maturation in the medulla and are delivered to peripheral lymphoid tissues. We examined the role of AML1, the gene encoding a transcription factor, in the above processes by using the transgenic mice expressing a dominant interfering form of AML1 as well as mice targeted heterozygously for AML1. One phenotypic change seen in the AML1-diminished mice was the reduction in the numbers of both CD4 SP and CD8 SP thymocytes, reflecting the partial impairment of the transition from the double-positive to SP stage. In addition, distinct from the above abnormality, perturbed were several aspects of SP cells, including the maturation of SP thymocytes, the recent thymic emigration, and the proliferative responsiveness of peripheral T cells to TCR stimulation. Interestingly, the AML1 diminution caused inhibitory and enhancing effects on the CD4 SP and CD8 SP cells, respectively. These differential effects are most likely related to the reduction in the peripheral CD4 SP/CD8 SP ratio observed in the AML1-diminished mice. The AML1 transcription factor thus maintains the homeostasis of each SP subset by functioning at the later stages of T lymphocyte differentiation.

Oral immunization with size-purified microsphere beads as a vehicle selectively induces systemic tolerance and sensitization

Oral administration of antigens has long been recognized as a method to prevent or delay the onset of diseases associated with untoward immune responses to self and non-self antigens. Although oral administration of antigens offers a convenient way to induce systemic tolerance, its therapeutic potential has been seriously limited by the fact that it requires repeated feeding of a large amount of antigens and that it may deteriorate ongoing autoimmune diseases when autoantigens are employed. We have previously shown that orally administered poly-D,L-lactic acid (PDLLA) microspheres containing an antigen were selectively distributed to Peyer's patches (PP) and systemic lymphoid tissues according to their diameter and then released the antigen over a long period of time. We now report that a single dose of intragastric immunization with a PDLLA microsphere 7-10 micrometer in diameter and containing 2 mg of OVA was as effective as 100 mg of water soluble OVA to suppress OVA-specific IgG and DTH response. This was associated with a large increase of Interferon-gamma production by PPT cells stimulated with an antigen and a small increase in secretory IgA specific to OVA. In contrast, administration of an antigen encapsulated in microspheres 3-4 microm in diameter led to an enhanced OVA-specific IgG response and no significant increase in OVA-specific secretory IgA. Thus, by utilizing microspheres of an appropriate diameter as a vaccination vehicle, we were able to selectively induce both systemic tolerance and sensitization by oral ingestion of single low dose of an antigen.

Diurnal motor activities of the esophagus in conscious dogs

Diurnal motor activities of the upper, middle, and lower thirds of the thoracic esophagus, the lower esophageal sphincter, and the gastric body were recorded in six conscious dogs, using extraluminal force transducers. The motor activities of the thoracic esophagus and the lower esophageal sphincter were divided into three major motility patterns: feeding, digestive, and interdigestive. Each motility pattern was basically composed of repetitive bursts of contractions that were clearly classified into type I and II according to their contractile properties. Type I bursts were peristaltic contractions initiated at the upper thoracic esophagus and sequentially propagated distally to include the sphincter. Propagation velocity and duration of type I contractions were similar in all three motility patterns, and these contractions never were propagated into the stomach. Type II bursts were nonperistaltic simultaneous contractions of the thoracic esophagus and lower sphincter appearing synchronously with phase III of gastric interdigestive migrating contractions. Amplitude and duration of type II contractions were maximal at the sphincter, suggesting initiation at that site. In nonfeeding patterns, type I contractions would clear the esophagus of refluxed gastric contents, while type II contractions would prevent reflux.

Interleukin-4-dependent induction of preproenkephalin in antigen-specific T helper-type 2 (Th2) cells

Naive Th cells obtained from OVA(323-339)-specific DO11.10 TCR-Tg mice did not express preproenkephalin (PPE) mRNA. However, culture of naive Th cells with OVA(323-339) peptide (OVA-pep) plus IL-2 under Th2-inducing conditions for 7 days resulted in an induction of PPE mRNA. The PPE mRNA was also induced by culturing with OVA-pep plus IL-2 (neutral condition). However, PPE mRNA induction under neutral conditions was totally abrogated by addition of anti-IL-4 mAb. The existence of methionine-enkephalin was also demonstrated in peptidase-digested peptides derived from Th2 cell lysate. These results demonstrate that IL-4 is a critical factor for the induction of PPE mRNA in freshly expanded antigen-specific Th2 cells.

Molecular basis for functional maturation of thymocytes: increase in c-fos translation with positive selection

In the process of positive selection, immature CD4+8+ double positive (DP) thymocytes expressing TCR reactive to self-MHC by appropriate avidity develop into mature thymocytes. Positive selection involves not only down-regulation of either CD4 or CD8 but also acquisition of immunocompetent potential such as cell proliferation and cytokine production. To understand the molecular basis for such functional maturation during the positive selection process, we examined whether nonselected DP, selected DP, and CD4+8- single positive thymocytes possess the activation potential for signaling pathways from mitogen-activated protein kinases (extracellular signal-regulated kinase and c-Jun N-terminal kinase) to AP-1. In response to stimulation, a marked induction of c-Fos protein expression as well as cell proliferation is detected only in CD4+8- single positive cells but not in selected and nonselected DP cells, though mitogen-activated protein kinase activities and c-fos transcripts are equally induced. In the presence of proteasome inhibitors, c-Fos protein became detectable in selected DP cells but still not in nonselected DP cells, suggesting that DP cells receiving positive selection signals acquire the capacity to translate the c-fos gene, but it may not be sufficiently high to overcome the degradation of c-Fos protein. These data indicate that the translating ability of the c-fos gene is up-regulated in the thymic positive selection process, from nonselected DP to CD4+8- single positive cells through positively selected DP cells. The distinguished responsiveness to stimulation in thymocytes with and without positive selection may be a result in part of the distinct regulation of the c-fos gene at the translational level.

Dietary nucleotides can up-regulate antigen-specific Th1 immune responses and suppress antigen-specific IgE responses in mice

BACKGROUND

It has been reported that dietary nucleotides enhance T helper cell activities. In this study, we have determined the effects of dietary nucleotides on antigen-specific Th1 and Th2 responses and IgE responses.

METHODS

Ovalbumin (OVA)-specific T cell receptor (TCR) transgenic (OVA-TCR Tg) mice, 3 weeks old, were fed a nucleotide-free diet (NT(-) diet) or the NT(-) diet supplemented with dietary nucleotides (NT(+) diet) for 4 weeks. Cytokine production by spleen cells and macrophages obtained from these mice was measured in vitro. BALB/c mice, 3 weeks old, immunized intraperitoneally with OVA adsorbed onto alum, were fed the NT(-) diet or the NT(+) diet for 4 weeks. Serum levels of antigen-specific antibodies in the BALB/c mice were determined by ELISA.

RESULTS

The level of production of antigen-specific interferon-gamma by spleen cells was significantly higher in the OVA-TCR Tg mice fed the NT(+) diet than in the control mice. The levels of secretion of bioactive IL-12 by spleen cells and peritoneal macrophages were also significantly increased in the NT(+) diet group. The serum OVA-specific IgE level was significantly decreased in BALB/c mice fed the NT(+) diet compared with those fed the NT(-) diet.

CONCLUSION

These results show that dietary nucleotides up-regulate the antigen-specific Th1 immune response through the enhancement of IL-12 production and suppress the antigen-specific IgE response.

Serum IgE response to orally ingested antigen: a novel IgE response model with allergen-specific T-cell receptor transgenic mice

BACKGROUND

The mechanism by which orally ingested allergens elicit an IgE response remains unclear because there are few animal models available for investigation of this response.

OBJECTIVE

We tried to develop a murine model suitable for investigation of the IgE response to orally ingested allergens, which would allow us to identify T cells that could promote IgE production.

METHODS

Ovalbumin (OVA)-specific T-cell receptor transgenic mice were fed a diet containing OVA, and both the serum antibody response and cytokine production by splenocytes were examined.

RESULTS

Oral administration of OVA to transgenic mice led to an increase in the levels of both antigen-specific IgE and total IgE in the sera. Subsequent intravenous challenge of OVA-fed transgenic mice with OVA resulted in anaphylactic shock. Analysis of cytokine production by splenocytes revealed that high IL-4-producing T cells appeared in the spleen 1 week after the start of feeding the OVA diet. T cells from these mice were found to promote IgE secretion by BALB/c B cells in vitro. This helper activity and the levels of IL-4 secretion were diminished after long-term feeding. These findings suggest the possibility that the orally ingested antigen elicited a response by a subpopulation of T cells that produce high levels of T(H2)-type cytokines and that promote IgE secretion, and these same T cells were tolerized by the orally ingested antigen.

CONCLUSION

This experimental model with transgenic mice may be a useful tool for further studies of the cellular and molecular mechanisms of the T-cell and IgE responses to orally ingested antigens.

Establishment of efficient reaggregation culture system for gene transfection into immature T cells by retroviral vectors

To overcome low efficiency of retroviral infection into immature T cells, we modified reaggregation fetal thymus organ culture by closely packed co-culture with virus-producing cells (VPC). The viral vector was constructed in chimeric vector, pMX, with IRES and tailless-rat CD2 as a surface marker of infected cells. A rearranged TCR beta gene (Vbeta8.2) was further inserted into the construct for investigating effect of the introduced gene in T cell development. Using this system, we succeeded to transfer the viral vector into immature thymocytes at a remarkably higher efficiency compared to conventional methods using medium containing retrovirus. Moreover, the introduced TCR beta gene was expressed on thymocytes of RAG2-deficient mice to induce in the transition of CD4-CD8- double-negative (DN) into CD4+CD8+ double-positive (DP) cells by transducing beta-selection signaling. Thus, our modified reaggregation culture system is useful for studying the molecular mechanism of T cell development due to a highly efficient gene transfer into immature T cells.

Primary response of naive CD4(+) T cells to amino acid-substituted analogs of an antigenic peptide can show distinct activation patterns: Th1- and Th2-type cytokine secretion, and helper activity for antibody production without apparent cytokine secretion

Naive CD4(+) T cells differentiate into two types of helper T cells showing an interferon-gamma-predominant (Th1) or an interleukin-4-predominant (Th2) cytokine secretion profile after repeated antigenic stimulation. Their differentiation can be influenced by slight differences in the interaction between the T cell receptor (TCR) and its ligand at the time of primary activation. However, the primary response of freshly isolated naive CD4(+) T cells to altered TCR ligands is still unclear. Here, we investigated the primary response of splenic naive CD4(+) T cells derived from transgenic mice expressing TCR specific for residues 323-339 of ovalbumin (OVA323-339) bound to I-A(d) molecules. Naive CD4(+) T cells secreted either Th1- or Th2-type cytokines immediately after stimulation with OVA323-339 or its single amino acid-substituted analogs. Helper activity for antibody secretion by co-cultured resting B cells was also found in the primary response, accompanied by either low-level Th2-type cytokine secretion or no apparent cytokine secretion. Our results clearly indicate that dichotomy of the Th1/Th2 cytokine secretion profile can be elicited upon primary activation of naive CD4(+) T cells. We also demonstrate that the helper activity of naive CD4(+) T cells for antibody production does not correspond to the amounts of the relevant cytokines secreted.

Distinct role of antigen-specific T helper type 1 (Th1) and Th2 cells in tumor eradication in vivo

The role of T helper type 1 (Th1) and Th2 cells in tumor immunity was investigated using Th cells induced from ovalbumin (OVA)-specific T cell receptor transgenic mice. Although Th1 cells exhibited stronger cytotoxicity than Th2 cells, both cell types completely eradicated tumors when transferred into mice bearing A20 tumor cells transfected with the OVA gene (A20-OVA). Th1 cells eradicated the tumor mass by inducing cellular immunity, whereas Th2 cells destroyed the tumor by inducing tumor necrosis. Both Th1 and Th2 cells required CD8(+) T cells to eliminate tumors, and neither of these cells were able to completely eliminate A20-OVA tumors from T and B cell-deficient RAG2(-/-) mice. Mice cured from tumors by Th1 and Th2 cell therapy rejected A20-OVA upon rechallenge, but CD8(+) cytotoxic T lymphocytes were induced only from spleen cells prepared from cured mice by Th1 cell therapy. Moreover, we demonstrated that Th1 and Th2 cells used distinct adhesion mechanisms during tumor eradication: the leukocyte function-associated antigen (LFA)-1-dependent cell-cell adhesion step was essential for Th1 cell therapy, but not for Th2 cell therapy. These findings demonstrated for the first time the distinct role of antigen-specific Th1 and Th2 cells during eradication of established tumors in vivo.

Transforming growth factor-beta secreted from CD4(+) T cells ameliorates antigen-induced eosinophilic inflammation. A novel high-dose tolerance in the trachea

The induction of peripheral tolerance is one of the feasible approaches for the control of autoimmunities and allergies. Tolerance induction in the intestine has been studied extensively and therapeutic applications to autoimmunities are in progress, whereas tolerance in the respiratory tract is poorly investigated. We examined the immunoregulatory mechanisms for evading exaggerated inflammatory responses in the murine airway mucosa. Administration of an optimal dose of ovalbumin (OVA) to the trachea elicited eosinophilic inflammation in the trachea of OVA/aluminum hydroxide-sensitized BALB/c mice, whereas higher doses were unable to do so. This failure paralleled the downregulation of interleukin-4 production by mediastinal lymph node (LN) T cells. This high-dose tolerance was attributable to the mechanisms of antigen (Ag)-specific suppression, because the adoptive transfer of CD4(+) LN T cells from the OVA-tolerant mice inhibited the OVA-specific, but not irrelevant Ag KLH-specific, eosinophilic responses. The inhibitory effects were neutralized by the intratracheal administration of anti-transforming growth factor (TGF)-beta, but not that of anti-interferon (IFN)-gamma, monoclonal antibodies, indicating that the high-dose tolerance was mediated by secreted TGF-beta, but not by the dominance of transferred T helper (Th)1 cells over Th2 cells. The pivotal role of TGF-beta was reinforced by the finding that the LN cells from the OVA-tolerant mice produced TGF-beta in response to the in vitro Ag stimulation. These results demonstrate a novel regulatory mechanism in the airway: that TGF-beta secreted by T cells plays an important role in the downmodulation of the immune responses to high doses of Ag which might otherwise induce deleterious inflammation in the airway mucosal tissues.

The essential role of phorbol ester-sensitive protein kinase C isoforms in activation-induced cell death of Th1 cells

Th1 and Th2 cells, which were induced from naive T cells of TCR-transgenic mice, showed differential sensitivity to activation-induced cell death (AICD) triggered by stimulation with anti-CD3 monoclonal antibody. The Th1 cells showed more rapid AICD than Th2 cells. This accelerated AICD of Th1 cells was strongly blocked by protein kinase C (PKC) inhibitors (H-7 or GF 109203X). Moreover, long-term treatment of Th1 cells with phorbol 12-myristate 13-acetate (PMA) caused the abrogation of anti-CD3-induced AICD in parallel with the disappearance of PMA-sensitive PKC isoforms such as PKC alpha, gamma, epsilon and theta. Therefore, it was clearly demonstrated that PMA-sensitive PKC isoforms are essential for AICD of Th1 cells. The different susceptibility to AICD between Th1 and Th2 cells was not due to their differential expression levels of PMA-sensitive PKC isoforms but appeared to be due to their differential requirement for PMA-sensitive isoforms in the up-regulation of Fas ligand which is involved in suicide killing of activated Th1 cells.

A case of amyloid goiter secondary to Crohn's disease

We herewith report a case of amyloid goiter secondary to Crohn's disease. The patient had been diagnosed as having Crohn's disease at the age of 15, and underwent right hemicolectomy at age 20. When he was 26 years old he complained of swelling of the anterior neck. Both TSH and thyroid hormones were within the normal range, and anti-thyroglobulin and anti-microsomal antibodies were negative. Only thyroglobulin was noticeably above the normal range. During the next year his goiter enlarged further and because he had a feeling of pressure he underwent total thyroidectomy. The presence of amyloid A protein in his surgical specimen led to the diagnosis of amyloid goiter. Although most cases of secondary amyloidosis are known to develop in neoplasms or chronic inflammatory diseases, our patient had no illness other than Crohn's disease. Perusal of literature revealed that Crohn's disease is rarely a cause of amyloid goiter.

A significant role of leptin in the generation of steroid-induced luteinizing hormone and prolactin surges in female rats

Recent evidence suggests that leptin, the product of obese (ob) gene, may play an important role in the regulation of reproductive function. However, a possible role of leptin in the preovulatory surges of luteinizing hormone (LH) and prolactin (PRL) in rodents has yet to be explored, and thus examined in this study. Experiments were performed on both normally fed and 3-day starved rats, which were ovariectomized and primed with estradiol and progesterone. At 11:00 h on the day of the experiments, normally fed rats received an intracerebroventricular injection of artificial cerebrospinal fluid, anti-leptin serum, or normal rabbit serum. Three-day starved rats were given artificial cerebrospinal fluid or recombinant human leptin (2.5 microgram) via the same route. From 11:00 to 18:00 h, blood was collected every 30 min to measure LH and PRL. The 3-day starvation completely abolished both LH and PRL surges, but leptin resumed these hormonal surges to the levels of normally fed rats. In addition, anti-leptin serum given to normally fed rats significantly depressed LH surge and delayed the onset of PRL surge. This study is the first to demonstrate that leptin plays a physiologically important role in the generation of steroid-induced LH and PRL surges in female rats.

CD45 can act as a negative regulator for the transition from early to late CD4+ CD8+ thymocytes

The differentiation process from CD4-CD8- double-negative (DN) thymocytes to CD4+CD8+ double-positive (DP) stage is accompanied by vigorous proliferation. The resulting DP cells contain a sizable proportion of large cycling cells, but most DP cells are small resting cells. To explore the molecular mechanisms which regulate cell proliferation of DP thymocytes prior to further development, we used TCR-transgenic (Tg) mice with non-selecting MHC (Tg-Neut), which contain almost exclusively DP thymocytes that are not subject to either positive or negative selection. In Tg-Neut, the thymus contained DP cells of relatively large size, which showed higher extracellular signal-regulated kinase activity and enhanced responsiveness to mitogen compared to small DP cells. This indicates that all the large DP cells in the thymus are not positively selected and that they possess proliferative potential. When Tg-Neut mice were backcrossed with CD45 knockout mice (CD454-/- Tg-Neut), the thymus showed an increase of large DP cells and cycling cells, but a decrease of apoptotic cells. Furthermore, Bcl-2 expression and Jun N-terminal kinase activity, which are associated with resistance to apoptosis, were enhanced. These observations suggest that thymocyte proliferation in the DP stage is suppressed by a CD45-related process with regulation of mitogen-activated protein kinase and Bcl-2 unless DP cells receive TCR-mediated signals.

Beta-selection of immature thymocytes is less dependent on CD45 tyrosinephosphatase

Tyrosine kinase p56lck plays a pivotal role in beta-selection from CD4-8- (DN) to CD4+8+ (DP) developing pathway, but it is unclear how CD45 transmembrane tyrosinephosphatase is involved in this process although CD45 activates p56lck by dephosphorylating its tyrosine-505. To analyze this issue, we produced double mutant mice of T-cell receptor transgenic mice (TCR-Tg) or RAG-2 knock out mice backcrossed with either p56lck or CD45 knock out mice. In TCR-Tg, CD25+DN thymocytes almost disappeared and CD25-44-DN cells of further developing stage increased, implying that all DN thymocytes can undergo beta-selection due to the expression of functionally rearranged TCR-beta on CD25+ DN thymocytes. However, CD25+ thymocytes increased in DN stage when TCR-Tg were backcrossed with p56lck deficient mice but not with CD45 deficient mice. Similarly, DP thymocyte induction with CD25+ cell reduction in RAG-2 knock out mice by injection of anti-CD3 mAb was inhibited in p56lck deficient but not in CD45 deficient mice. This suggests that CD45 is dispensable for beta-selection though p56lck is required.

Ex vivo evidence for asymmetric tyrosine phosphorylation of ZAP-70 on double-positive thymocytes in the positive selection process

Antigen stimulation via TCR in mature T cells provides rapid induction of tyrosine phosphorylation of intracellular substrates including ZAP-70. To study the potential involvement of tyrosine phosphorylation in CD4+CD8+ [double-positive (DP)] thymocytes in the positive selection process in vivo, we isolated and analyzed them in the presence of phosphatase inhibitor. DP thymocytes were obtained from TCR transgenic mice (TCR-Tg) expressing MHC class I- or class II-restricted TCR in selecting and non-selecting MHC backgrounds respectively. The phosphorylation of ZAP-70 in DP thymocytes of class I-restricted TCR-Tg was significantly higher in the positively selecting background than in the non-selecting one. However, such a phosphorylation difference between selecting and non-selecting TCR-Tg was found to be considerably less in class II-restricted TCR-Tg. A similar bias for ZAP-70 phosphorylation was also observed on selecting DP thymocytes when I-A(beta) deficient- and beta2-microglobulin-deficient mice were compared. These ex vivo studies suggest that TCR-mediated signaling on DP thymocytes induces ZAP-70 phosphorylation under a different manner of engagement of TCR to class I and class II molecules in the positive selection process.

Reconstitution of immune systems in RAG2-/- mice by transfer with interleukin-12-induced splenic hematopoietic progenitor cells

The administration of a high dose of IL-12 into the mice resulted in the induction of splenomegaly. From the flow cytometry analysis of cellularity in an enlarged spleen, it was demonstrated that Thyl.2-CD45RB-c-Kit + Sca-1 + Lin- hematopoietic progenitor cells markedly increased in IL-12-administered mouse spleen compared with untreated mouse spleen. The IL-12-induced hematopoietic progenitor cells showed a greatly enhanced colony-forming activity in CFU-granulocyte/macrophage (CFU-GM), blast-forming units-erythroid (BFU-E) and CFU-spleen (CFU-S) assay. Moreover, it was initially demonstrated that the transfer of IL-12-induced splenic hematopoietic progenitor cells into immunodeficient RAG2-/- mice caused a complete reconstitution of their immune functions including T- and B-cell-mediated immunity. Thus, the evidence that IL-12 has a capability of inducing hematopoietic progenitor cells possessing stem cell-like activity in vivo, indicated another important immunomodulating activity of IL-12 in immunotherapy.

Synovial sarcoma of the esophagus: report of a case

Synovial sarcomas are exceedingly rare neoplasms of the digestive tract. We herein report a case of a synovial sarcoma occurring in the esophagus of a 20-year-old man. He had a history of acute lymphocytic leukemia and had undergone aggressive chemotherapy between the ages of 4 and 8 years. The tumor, which was large and extended into the upper mediastinum, was successfully resected without an esophagectomy via the cervical approach. After postoperative radiation and chemotherapy, the patient remained healthy, without any evidence of disease 20 months after the operation.

The restraint stress drives a shift in Th1/Th2 balance toward Th2-dominant immunity in mice

When mice were physically restrained in 50-ml tubes for 24 h, a marked decrease of NK activity was demonstrated in parallel with the elevation of serum corticosterone levels. The release of mice from restraint stress resulted in the recovery of NK activity, with a decrease of serum corticosterone levels within 48 h. Using this stress model, we also investigated the influence of restraint stress on mouse Th1/Th2 balance. Consistent with the decrease of NK activity, IFN-gamma production of mouse spleen cells greatly reduced after suffering from restraint stress. In contrast, the IL-4 producing ability of spleen cells was not so much affected by restraint stress. These results initially indicated that stress may induce the skewing of the Th1/Th2 balance toward Th2-dominant immunity, which stimulates the occurrence of infectious diseases and allergic disorders.

Different roles of brain interleukin 1 in the adrenocorticotropin response to central versus peripheral administration of lipopolysaccharide in the rat

Although it is well established that peripheral administration of endotoxin activates the hypothalamic-pituitary-adrenal (HPA) axis, information is very limited regarding whether central administration of endotoxin can similarly stimulate the endocrine axis. Moreover, it is also unknown whether a difference exists in the mode of involvement of brain-derived cytokines in determining the HPA response to peripheral vs central administration of endotoxin. In the present study, the authors attempted to gain more knowledge on these issues focusing on interleukin (IL) 1 in the brain, one of key pro-inflammatory cytokines mediating the immuno-endocrine network. In male rats, both intravenous (i.v., 100 micrograms/kg body weight) and intracerebroventricular [i.c.v. (the 3rd ventricle), 10 micrograms] injections of Escherichia coli lipopolysaccharide (LPS) caused a significant elevation of adrenocorticotropin (ACTH) levels in plasma, even though peaked ACTH responses occurred earlier after the i.v. (60 min post-injection) than the i.c.v. (120 min post-injection) LPS. Although the ACTH response to i.c.v. LPS was significantly suppressed by a prior (5 min) i.c.v. administration of IL-1 receptor antagonist (IL-1Ra, 1 microgram), the hormonal response to i.v. LPS was not. That this dose of IL-1Ra was not biologically a small dose was indicated by another experiment that the same dose of i.c.v. IL-1Ra was able to significantly suppress the ACTH response to an i.c.v. injection of recombinant human IL-1 beta (50 ng). These results suggest that i.c.v. LPS, as i.v. LPS, can stimulate ACTH secretion in the rat, and this hormonal response may, at least in part, be mediated by brain-derived IL-1. Although there is one previous study reporting an important role of central IL-1 in mediating the HPA response to systemic LPS treatment, our present data suggest that such a mechanism may not operate before and during an early, peak phase of ACTH secretion after i.v. LPS.

Evidence of stage-specific element for germ-line transcription of the TCR alpha gene located upstream of J alpha49 locus

T cell receptor (TCR) genes are rearranged and expressed in an ordered manner during T cell development. The basic mechanism regulating this stepwise DNA alteration is poorly understood. To address this issue, we explored the presence of a stage-specific element for germ-line transcription of the TCR alpha gene which is closely associated with gene rearrangement. First, germ-line transcription of the TCR alpha gene including the first segment of the J alpha locus, J alpha49, was delayed compared to that of the TCR beta gene in both normal and TCR-transgenic (Tg) mice. Furthermore, expression of this transcript could be induced by CD3epsilon-mediated signals in recombination-activating gene (RAG)-2-deficient mice. In TCR-Tg mice, the endogenous J alpha49 germ-line transcript could not yet be observed at the CD25+ double-negative (DN) stage when the TCR alpha transgene was expressed. Of immature T cell hybridomas derived from either scid thymocytes (CD25+ DN) or immature CD8-single positive (ISP) thymocytes, only the latter hybridoma expressed the J alpha49 germ-line transcript. These data indicate that the J alpha49 germ-line transcription occurs only at a specific developmental stage. Second, to determine which elements may be regulating stage specificity, we performed transient transfection analysis with a reporter gene and demonstrated that the upstream region of the J alpha49 locus possesses promoter activity in correlation with germ-line transcription in ISP-derived but not in SCID-derived hybridomas. These results indicate that the expression of TCR alpha germ-line transcripts is regulated in a stage-specific manner by a cis-element located within the J alpha locus.

Measurement of cytokines in the cavernous sinus plasma from patients with Cushing's disease

In order to know more about the in vivo secretion of various cytokines from the human pituitary, this study measured the concentrations of interleukin (IL)-1alpha, IL-1beta, IL-2, IL-6, tumor necrosis factor-alpha and IL-1 receptor antagonist (ra) in both the peripheral blood and the cavernous sinus (CS) plasma from six patients with Cushing's disease before and after an intravenous bolus injection of human corticotropin-releasing hormone (CRH, 100 microg). As a routine procedure for the diagnosis of Cushing's disease, adrenocorticotropin (ACTH) levels were also determined in the same samples. In four of the six patients, unstimulated levels of IL-1ra in the CS ipsilateral to the ACTH-secreting adenoma were higher than those in the peripheral blood, with a ratio of > or = 1.5:1, even though CRH was without effect on the cytokine's concentration in the CS. In contrast, no consistent data were obtained for any of the remaining five cytokines. These results demonstrate for the first time that the in vivo release of IL-1ra is detectable in at least some corticotroph adenomas, and also suggest a possible role of the cytokine in physiological and pathophysiological processes occurring in the human pituitary.

Lactobacillus casei inhibits antigen-induced IgE secretion through regulation of cytokine production in murine splenocyte cultures

BACKGROUND

Lactobacillus casei is a nonpathogenic gram-positive bacterium widely used in dairy products and has been shown to enhance the cellular immunity of the host.

METHODS

To examine the inhibitory effect of L. casei on IgE production, splenocytes obtained from ovalbumin (OVA)-primed BALB/c mice were restimulated in vitro with the same antigen in the presence of heat-killed L. casei. The effect of this bacterium on T helper (Th) phenotype development was also examined with naive T cells from OVA-specific T cell receptor-transgenic mice.

RESULTS

L. casei induced IFN-gamma, but inhibited IL-4 and IL-5 secretion, and markedly suppressed total and antigen-specific IgE secretion by OVA-stimulated splenocytes. The inhibitory effect of L. casei on IgE, IL-4, and IL-5 production was partially abrogated by addition of neutralizing antibody to IFN-gamma. Augmented IL-12 production was also observed in the cell cultures containing L. casei, and anti-IL-12 monoclonal antibody completely restored the IgE, IL-4, and IL-5 production to the control levels. The IL-12 augmentation by L. casei was macrophage-dependent. The Th cell development assay showed the ability of L. casei to induce Th1 development preferentially. This effect was also completely blocked by anti-IL-12 antibody.

CONCLUSIONS

This is the first demonstration that a nonpathogenic microorganism, L. casei, can inhibit antigen-induced IgE production through induction of IL-12 secretion by macrophages. The findings suggest a potential use of this organism in preventing IgE-mediated allergy.

Accumulation of IL-12-activated antitumor effector cells into lymph nodes of tumor-bearing mice

Simultaneous administration of high dose of IL-12 into tumor-inoculated mice resulted in a marked reduction of tumor growth in parallel with the augmented generation of cytotoxic T-cells, natural killer (NK) cells and IFN-gamma-producing Th cells. We found that these IL-12-activated antitumor effector cells preferentially accumulated in peripheral lymph nodes concomitantly with lymphadenopathy. However, IL-12 rather induced disappearance of antitumor effector cells including CD4+ T, CD8+ T and NK cells from spleen in spite of inducing splenomegaly. Lymph node cells obtained from IL-12-treated B16F0-bearing mice showed a marked IFN-gamma production in response to not only IL-2, IL-12, anti CD3 mAb but also B16F0 melanoma cells. Moreover, they could lyse B16F0 melanoma cells in a long-term cytotoxicity assay. It was also confirmed that IL-12-activated IFN-gamma producing Th1 cells were accumulated in tumor local site. Thus, IL-12 appeared to have a capability of stimulating selective migration of antitumor cells into lymph nodes and tumor local sites.

Interleukin 7 transgenic mice develop chronic colitis with decreased interleukin 7 protein accumulation in the colonic mucosa

We have demonstrated that intestinal epithelial cells produce interleukin 7 (IL-7), and IL-7 serves as a potent regulatory factor for proliferation of intestinal mucosal lymphocytes expressing functional IL-7 receptor. To clarify the mechanism by which locally produced IL-7 regulates the mucosal lymphocytes, we investigated IL-7 transgenic mice. Here we report that transgenic mice expressing murine IL-7 cDNA driver by the SRalpha promoter developed chronic colitis in concert with the expression of SRalpha/IL-7 transgene in the colonic mucosa. IL-7 transgenic but not littermate mice developed chronic colitis at 4-12 wk of age, with histopathological similarity to ulcerative colitis in humans. Southern blot hybridization and competitive PCR demonstrated that the expression of IL-7 messenger RNA was increased in the colonic mucosal lymphocytes but not in the colonic epithelial cells. IL-7 protein accumulation was decreased in the goblet cell-depleted colonic epithelium in the transgenic mice. Immunohistochemical and cytokine production analysis showed that lymphoid infiltrates in the lamina propria were dominated by T helper cell type 1 CD4+ T cells. Flow cytometric analysis demonstrated that CD4+ intraepithelial T cells were increased, but T cell receptor gamma/delta T cells and CD8alpha/alpha cells were not increased in the area of chronic inflammation. Increased IL-7 receptor expression in mucosal lymphocytes was demonstrated in the transgenic mice. These findings suggest that chronic inflammation in the colonic mucosa may be mediated by dysregulation of colonic epithelial cell-derived IL-7, and this murine model of chronic colitis may contribute to the understanding of the pathogenesis of human inflammatory bowel disease.

Manipulation of Th1/Th2 balance in vivo by adoptive transfer of antigen-specific Th1 or Th2 cells

We have investigated the possibility that the Th1/Th2 balance in vivo may be modulated by adoptive transfer of Th1 or Th2 cells induced in vitro. Thl cells were induced from I-Ad-binding OVA323-339-specific T-cell receptor-transgenic (TCR-Tg) mouse spleen cells by culturing with OVA323-339 peptide and antigen presenting cells (APC) in the presence of IL-2, IL-12 and anti-IL-4 mAb. Th2 cells were induced from TCR-Tg mouse spleen cells by culturing with IL-2, IL-4 and anti-IL-12 mAb in addition to OVA323-339 plus APC. Immunomodulating activities of both Th1 and Th2 cells were determined by their effect on delayed type hypersensitivity (DTH) responses or cytokine production. No significant DTH responses (footpad swelling) were observed in untreated BALB/c mice following a single injection of OVA323-339-pulsed syngeneic spleen cells. However, adoptive transfer of Th1 cells into BALB/c mice induced strong dose dependent DTH responses in response to I-Ad-bound OVA323-339 but not unrelated peptide. In contrast, only slight DTH responses were detected in BALB/c mice transferred with Th2 cells. In parallel with the DTH responses, increased levels of serum IFN-gamma were demonstrated in mice adoptively transferred with Th1, while no significant increase was observed in Th2-transferred mice. In vitro analysis also demonstrated that both spleen cells and popliteal lymph node cells prepared from Th1-transferred mice showed Th1-type cytokine production, while cells obtained from Th2-transferred mice revealed Th2-dominant cytokine production. Such immune deviation induced by antigen-specific Th1 cells was demonstrated up to three months after cell transfer. Therefore, it may be possible to manipulate the Th1/Th2 balance in vivo by adoptive transfer of antigen-specific Th1 or Th2 cells.

TGF-beta induced by oral tolerance ameliorates experimental tracheal eosinophilia

Induction of peripheral tolerance is one of the feasible approaches for the control of autoimmunities and allergies. Therapeutic applications of oral tolerance to autoimmunities are in progress both experimentally and clinically, while those to allergies have been poorly investigated. We examined the induction of CD4+ T cells with suppressive properties by oral tolerance and the mechanism by which these cells down-regulated Ag-induced eosinophilia in the trachea. Feeding of mice transgenic for anti-OVA TCR with high doses of OVA inhibited the airway eosinophilic inflammation induced by the intratracheally administered Ag. This inhibition reflected the mechanism of active suppression, since the inhibitory effect was adoptively transferred by splenic CD4+ T cells from the transgenic mice fed with high doses of OVA. The Ag specificity of the suppressor T cells was documented by the failure of spleen cells from mice that were orally tolerant of OVA to suppress irrelevant Ag, KLH-specific airway eosinophilic inflammation. The suppressive effect of the transferred T cells on eosinophil recruitment was neutralized by anti-TGF-beta mAb, but not anti-IFN-gamma mAb, indicating that the suppression is due to the inhibitory effect by secreted TGF-beta, but not to the dominance of the transferred Th1 cells over Th2 cells. This is the first study to reveal a link between oral tolerance and the regulation of Th2-mediated experimental tracheal eosinophilia through TGF-beta. Our experimental model suggests possible therapeutic applications of oral tolerance for the treatment of allergic disorders such as bronchial asthma.

TGF-beta induced by oral tolerance ameliorates experimental tracheal eosinophilia

Induction of peripheral tolerance is one of the feasible approaches for the control of autoimmunities and allergies. Therapeutic applications of oral tolerance to autoimmunities are in progress both experimentally and clinically, while those to allergies have been poorly investigated. We examined the induction of CD4+ T cells with suppressive properties by oral tolerance and the mechanism by which these cells down-regulated Ag-induced eosinophilia in the trachea. Feeding of mice transgenic for anti-OVA TCR with high doses of OVA inhibited the airway eosinophilic inflammation induced by the intratracheally administered Ag. This inhibition reflected the mechanism of active suppression, since the inhibitory effect was adoptively transferred by splenic CD4+ T cells from the transgenic mice fed with high doses of OVA. The Ag specificity of the suppressor T cells was documented by the failure of spleen cells from mice that were orally tolerant of OVA to suppress irrelevant Ag, KLH-specific airway eosinophilic inflammation. The suppressive effect of the transferred T cells on eosinophil recruitment was neutralized by anti-TGF-beta mAb, but not anti-IFN-gamma mAb, indicating that the suppression is due to the inhibitory effect by secreted TGF-beta, but not to the dominance of the transferred Th1 cells over Th2 cells. This is the first study to reveal a link between oral tolerance and the regulation of Th2-mediated experimental tracheal eosinophilia through TGF-beta. Our experimental model suggests possible therapeutic applications of oral tolerance for the treatment of allergic disorders such as bronchial asthma.

The serum factor from patients with ulcerative colitis that induces T cell proliferation in the mouse thymus is interleukin-7

The disturbance of immune regulatory T cells is related to the pathogenesis of ulcerative colitis. Here we demonstrated and characterized the serum factor from ulcerative colitis patients that induced proliferation of intrathymic T cells. The factor isolated from the patient sera by a combination of gel filtration and anion-exchange chromatography induced proliferation of CD4+CD8- intrathymic T cells in the organ-cultured embryonic mouse thymus. Purification and amino acid sequence analysis of the serum factor demonstrated that the N-terminal 12 sequence was homologous to that of interleukin-7. SDS-PAGE and Western blot confirmed that purified serum factor was interleukin-7. Enzyme immunoassay demonstrated that the serum interleukin-7 concentration was significantly increased in the patients. PCR and Southern blot hybridization demonstrated that interleukin-7 mRNA expression was increased in the thymus tissues from patients but decreased in the colonic mucosa. Since interleukin-7 is a crucial cytokine for proliferation and differentiation of T cells in the thymus, the present study indicates that interleukin-7 may contribute to the disturbance of immune regulatory T cells in ulcerative colitis.

The role of phorbol ester-sensitive protein kinase C isoforms in lymphokine-activated killer cell-mediated cytotoxicity: dissociation between perforin-dependent and Fas-dependent cytotoxicity

Treatment of lymphokine-activated killer (LAK) cells with phorbol ester (PMA) caused the downmodulation of LAK activity concomitantly with the inhibition of serine esterase (SE) release, which has been shown as a marker for perforin-dependent cell-mediated cytotoxicity. The reduction of perforin-dependent LAK activity by PMA-treatment appeared to be due to the disappearance of PMA-sensitive protein kinase C (PKC) isoforms such as PKC alpha, gamma, epsilon, theta. In contrast, Fas-mediated LAK activity was refractory against PMA-induced downregulation. Treatment of LAK cells with PMA caused a disappearance of cytotoxicity against Fas L5178Y tumor cells, while cytotoxicity against Fas+ transfectants was not affected by PMA treatment. Moreover, Fas-mediated LAK activity of perforin-knockout mice was not inhibited by PMA treatment. These results clearly demonstrated that Fas-mediated cytotoxicity could be dissociated from perforin-mediated cytotoxicity by their different requirement of PMA-sensitive PKC isoforms.

Involvement of IL-4-producing Vbeta8.2+ CD4+ CD62L- CD45RB- T cells in non-MHC gene-controlled predisposition toward skewing into T helper type-2 immunity in BALB/c mice

It was found that freshly isolated BALB/c CD4+ T cells produced high levels of IL-4 and IL-10 in response to immobilized anti-CD3 mAb, while C57BL/6 CD4+ T cells produced low amounts of IL-4 and IL-10. The high IL-4-producing ability of BALB/c mice was demonstrated to be genetically dominant and it was controlled by non-MHC gene (or genes). The cells responsible for IL-4 production in BALB/c mice were defined as TCRVbeta8.2+ CD4+ CD62L- CD45RB- memory-type T cells, which were distinct from NK1.1+ CD4+ NKT cells. Although these memory-type T cells were also detected in C57BL/6 mouse spleen at the same frequency, they showed a functionally different property from BALB/c CD4+ CD62L- CD45RB- T cells in terms of IL-4 production. The fact that germfree BALB/c mouse spleen cells also produced high levels of IL-4 suggested that the IL-4 producer in BALB/c mice might be developed under the influence of unknown factors other than environmental Ags. The CD4+ CD62L- CD45RB- T cells obtained from BALB/c mice accelerated the development of IL-4-producing memory-type CD4+ T cells from CD4+ CD62L+ CD45RB+ naive T cells prepared from OVA-specific TCR-transgenic mice. Therefore, IL-4-producing CD4+ CD62L- CD45RB- T cells might play an important role in the preferential induction of Th2-dominant immunity in BALB/c mouse strain.

Involvement of IL-4-producing Vbeta8.2+ CD4+ CD62L- CD45RB- T cells in non-MHC gene-controlled predisposition toward skewing into T helper type-2 immunity in BALB/c mice

It was found that freshly isolated BALB/c CD4+ T cells produced high levels of IL-4 and IL-10 in response to immobilized anti-CD3 mAb, while C57BL/6 CD4+ T cells produced low amounts of IL-4 and IL-10. The high IL-4-producing ability of BALB/c mice was demonstrated to be genetically dominant and it was controlled by non-MHC gene (or genes). The cells responsible for IL-4 production in BALB/c mice were defined as TCRVbeta8.2+ CD4+ CD62L- CD45RB- memory-type T cells, which were distinct from NK1.1+ CD4+ NKT cells. Although these memory-type T cells were also detected in C57BL/6 mouse spleen at the same frequency, they showed a functionally different property from BALB/c CD4+ CD62L- CD45RB- T cells in terms of IL-4 production. The fact that germfree BALB/c mouse spleen cells also produced high levels of IL-4 suggested that the IL-4 producer in BALB/c mice might be developed under the influence of unknown factors other than environmental Ags. The CD4+ CD62L- CD45RB- T cells obtained from BALB/c mice accelerated the development of IL-4-producing memory-type CD4+ T cells from CD4+ CD62L+ CD45RB+ naive T cells prepared from OVA-specific TCR-transgenic mice. Therefore, IL-4-producing CD4+ CD62L- CD45RB- T cells might play an important role in the preferential induction of Th2-dominant immunity in BALB/c mouse strain.