Absolute auditory threshold and threshold of unpleasantness of chronic schizophrenic patients and normal controls.

Modified the method of average error for research in schizophrenia and used this in establishing both the absolute auditory threshold and the threshold of unpleasantness. Results show chronic schizophrenic patients had a higher absolute threshold but a lower threshold for when a tone became unpleasnatly loud. Results (a) indicate that chronic schizophrenic patients find external stimulation aversive, (b) point out the narrow range of auditory stimuli in which schizophrenics function, and (c) suggest that the same auditory stimuli cannot be considered equivalent for schizophrenic patients and normal controls. (16 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

p40 molecule regulates NK cell activation mediated by NK receptors for HLA class I antigens and TCR-mediated triggering of T lymphocytes

p40 was previously described as a regulatory molecule capable of inhibiting both the natural and the CD16-mediated cytotoxicity of NK cells. In this study, we analyze the effect of p40 molecule engagement on the NK cell triggering induced by activating HLA class I-specific NK receptors (NKR) or on TCR alpha beta-mediated T cell activation. CD3-CD16+ NK cell clones expressing activating NKR (either CD94 or p50) were analyzed in a redirected killing assay using P815 target cells and appropriate mAb. A strong target cell lysis was detected in the presence of anti-NKR or anti-CD16 mAb alone. Addition of anti-p40 mAb resulted in a strong inhibition of both anti-NKR or anti-CD16 mAb-induced cytolysis. mAb specific for either CD45 or lymphocyte function associated antigen-1 did not exert any inhibitory effect in the same experimental system. Free intracellular calcium ([Ca2+]i) increase induced by mAb cross-linking of activating CD94 or p50 was inhibited by simultaneous engagement of p40 molecules, but not of other NK surface molecules including CD44 and CD56. In addition, cross-linking of p40 molecules strongly inhibited the CD94-induced tumor necrosis factor-alpha and IFN-gamma production. Analysis of TCR alpha beta or gamma delta T cell clones revealed that the engagement of p40 molecules, using specific mAb, induced some degree of inhibition only on anti-V beta (but not anti-V delta or anti-CD3) mAb-induced cytotoxicity. On the other hand, the p40 molecule engagement prevented T cell proliferation induced by either anti-V beta 8 or anti-V delta 2 mAb. A similar inhibitory effect was found on the IL-2-induced NK cell proliferation. Taken together, our present findings suggest that p40 may play a role in the regulation of NK and T lymphocyte activation and proliferation.     

Regulation of CD4 T cell reactivity to self and non-self

While the thymus may be effective in inducing tolerance to lymphoid associated antigens, it is not as efficient in deleting T cells reactive to peripheral tissue specific antigens. Therefore, to maintain self tolerance to peripheral tissues, post-thymic mechanisms must be invoked. One important way to prevent autoimmune pathology mediated by autoreactive CD4 T cells is the diversion of clones to regulatory Th2 effector cells. However, many different factors contribute in vivo to the decision of stimulated CD4 T cells to develop into Th1 versus Th2 cells. For example, T cell signaling pathways may influence the types of cytokines produced by naive T cells, and studies have provided evidence for a genetic polymorphism among common mouse strains that can significantly influence the early cytokine production in stimulated naive CD4 T cells. The allele carried by the BALB/c strain promotes IL-4 production, and consequently provides resistance to autoimmune diabetes in our transgenic mouse model. In addition, antigen presenting cells can influence the development of stimulated CD4 T cells in part through the production of cytokines such as IL-12. The absorption of IL-12 in vivo can permit the expansion of Th2 type effector cells, and this phenomenon will also protect mice from autoimmunity. Finally, the relative potency of various class II positive antigen presenting cell types can influence the development of autoreactive T cells, with dendritic cells apparently being the strongest stimulator of Th1 responses. Consistent with this notion, a relB knockout mouse, which is missing dendritic cells, appears to drive Th2 development even in response to viral infection. In sum, these various influences over the Th1/Th2 decision in vivo may provide new targets for immunotherapy of autoimmune diseases.     

Dendritic cells, interleukin 12, and CD4+ lymphocytes in the initiation of class I-restricted reactivity to a tumor/self peptide

Cell-mediated immunity involving CD8+ lymphocytes is effective in mediating rejection of murine mastocytoma cells bearing P815AB, a tumor-associated and self antigen showing similarity to tumor-specific shared antigens in humans. Although this antigen may act as an efficient target for class I-restricted responses in immunized mice, neither P815AB expressed on tumor cells nor a related synthetic nonapeptide will activate unprimed CD8+ cells for in vivo reactivity, measured by skin test assay. We review evidence showing that the failure of P815AB to initiate CD8+ cell reactivity may be due to defective recruitment of accessory and Th1-like cells to the afferent phase of the response initiated by transfer of mice with dendritic cells pulsed in vitro with the P815AB peptide. Although the copresence of a T helper peptide in dendritic cell priming in vitro with P815AB may compensate for the poor generation of accessory and Th1 cells in the adoptively transferred mice, recombinant IL-12 can replace the helper peptide in both effects. Effective priming to P815AB in vivo is achieved by either exposing dendritic cells to IL-12 prior to P815AB priming or administering the recombinant cytokine in vivo. Different approaches suggest that IL-12 may act both on accessory cells to improve presentation of previously undescribed class II-restricted epitopes of P815AB and on CD4+ cells to improve recognition of such epitopes. In particular, at the CD4+ cell level, IL-12 apparently acts as an adjuvant and an inhibitor of anergy induction. These data offer useful information for developing vaccination strategies using dendritic cells and class I-restricted tumor peptides in humans.     

Activation and peripheral expansion of murine T-cell receptor gamma delta intraepithelial lymphocytes

BACKGROUND & AIMS: The intestinal epithelial compartment is populated by CD8(+) alpha beta and gamma delta intraepithelial lymphocytes (IELs), which monitor the integrity of the epithelial barrier. alpha beta IELs are activated by peptide antigens presented by class I major histocompatibility complex (MHC) molecules, but it is unclear how gamma delta IELs are activated. METHODS: G8 T-cell receptor (TCR) gamma delta transgenic (Tg) mice (specific for the class I MHC alloantigen, T22/10(b)) were crossed to class I MHC-deficient beta2-microglobulin-knockout (beta2m degrees) mice, and Tg+ IELs were examined for relative yields and surface and functional phenotype. RESULTS: Evidence for class I MHC-induced activation of Tg+ IELs was supported by the detection of 4-fold greater numbers of Tg+ IELs in G8 x beta2m+ mice that proliferated at 15-fold higher levels than IELs from G8 x beta2m degrees mice. However, expression of CD69, production of cytokine (interleukin 2 and interferon gamma), and detection of cytolytic function for IELs in G8 x beta2m degrees mice suggested that class I MHC was not required for gamma delta IEL development or maturation. CONCLUSIONS: These results suggest that CD8(+) TCR gamma delta IELs do not require class I MHC for development but support the notion that antigens presented by class I MHC molecules are involved in the peripheral expansion and differentiation of this subset.     

The presentation of self and allogeneic MHC peptides to T lymphocytes

The presentation of donor-derived MHC peptides by recipient APCs to T cells is an essential component of the rejection of allografts (indirect allorecognition). Initial alloreactive T cell response is confined to a few well processed and presented dominant determinants on donor MHC. However, during long-term graft rejection, T cell response spreads to formerly poorly presented cryptic allogeneic MHC peptides. This phenomenon is likely to play an important role in the amplification and the perpetuation of the rejection process. Additionally, we present evidence that T cell repertoire selection to allogeneic MHC peptides is acquired via recognition of self-MHC peptides presented in the thymus during ontogeny. Supporting this view, we have shown that indirect alloresponses can lead to self-T cell tolerance breakdown to cross-reactive determinants on self-MHC molecules or alternatively that sensitization of recipients to self-MHC peptides can lead to accelerated graft rejection. It is therefore essential to determine the factors which govern the processing and presentation of self and allogeneic MHC molecules and to elucidate the mechanisms regulating subsequent T cell responses in order to design antigen-specific based immune therapies in transplantation.     

Negative regulation of antigen receptor signaling in lymphocytes

The purpose of this study was to assess the influence of an experimentally induced light premature occlusal contact on tooth sensation. This assessment involved monitoring the electric tooth pain threshold (TPT) at multiple times before and after altering the occlusal contact. This alteration was produced by placing high inlays, which were measured with a custom made measuring device in maximum intercuspation. Data were collected on 10 teeth in 5 subjects, all whom were male and between the ages of 24 and 30 years. The contact area of the high inlays varied from 75 microm to 193 microm. The TPT changes in these teeth ranged from -43 to +21% of their baseline level. Seven of these teeth showed a significant decrease (P < 0.05) in the TPT, one showed an increase and two did not show a significant change. Two of the teeth with a decreased TPT had cold water triggered occlusal pain, and 2 teeth had only occlusal pain. After several inlay adjustments to eliminate interference in maximum intercuspation, all tested teeth returned to their TPT baseline level and all symptoms disappeared. These results suggested that a light premature occlusal contact may change tooth sensation.     

Cabin 1, a negative regulator for calcineurin signaling in T lymphocytes

Rectus femoris surgery was performed on 70 patients with cerebral palsy and stiff-knee gait. Fifty-three patients underwent distal rectus transfer, and 17 patients had distal rectus release with complete muscle mobilization. Gait analysis was performed preoperatively and postoperatively at a minimum of 1 year. Swing-phase peak knee flexion (PKF) was improved in the transfer group, allowing improved foot clearance and more efficient gait (p = 0.04). PKF in swing deteriorated slightly in the release group (p = 0.04). The presence of abnormal swing-phase electromyogram (EMG) activity in the rectus alone or abnormal combined rectus and vastus lateralis activity did not influence the PKF results in either surgery (p < 0.05). The Ely test had no predictive value in identifying patients with abnormal EMG activity (p > 0.05). Preoperative knee range of motion was not a significant variable in determining relative success of rectus surgery. No deleterious effects were observed in stance phase in either group (p > 0.05).     

LAT is required for TCR-mediated activation of PLCgamma1 and the Ras pathway

In this study, we present the further characterization of a mutant Jurkat T cell line, J.CaM2, that is defective in TCR-mediated signal transduction. Although initial TCR-mediated signaling events such as the inducible tyrosine phosphorylation of the TCR-zeta chain and ZAP-70 are intact in J.CaM2, subsequent events, including increases in intracellular calcium, Ras activation, and IL-2 gene expression are defective. Subsequent analysis of J.CaM2 demonstrated a severe deficiency in pp36/LAT expression, a recently cloned adaptor protein implicated in TCR signaling. Importantly, reexpression of LAT in J.CaM2 restored all aspects of TCR signaling. These results demonstrate a necessary and exclusive role for LAT in T cell activation.     

The threshold for immune cell reactivity to milk antigens decreases in cow's milk allergy with intestinal symptoms

BACKGROUND: In cow's milk allergy (CMA) with intestinal symptoms, peripheral blood mononuclear cells (PBMCs) secrete tumor necrosis factor-alpha (TNF-alpha), altering intestinal function. However, the type of cow's milk protein (CMP) that triggers symptoms (intact or intestinally processed) is not known, and neither is the minimal amount required. METHODS: PBMCs were isolated from infants with active CMA or cured infants just before a new challenge and stimulated with intact or intestinally processed CMP. Supernatants were tested for cytokine content and for their ability to perturb intestinal barrier capacity, measured in Using chambers in HT29-19A intestinal cells. RESULTS: PBMCs from infants with active CMA secreted more TNF-alpha, when they were stimulated with intact rather than intestinally processed CMPs, and more TNF-alpha than PBMCs from cured infants. Accordingly, supernatants from PBMCs stimulated with intact but not intestinally processed CMPs significantly increased intestinal permeability. The CMP concentration required to trigger TNF-alpha secretion capable of altering intestinal function was very small in infants with active CMA (approximately 2 micrograms/ml), but about 300 times higher in cured infants. CONCLUSION: Intact rather than intestinally processed proteins stimulate PBMCs to release TNF-alpha and alter intestinal barrier capacity. The threshold for PBMC reactivity to milk antigens drops considerably during active CMA with intestinal symptoms.     

Differential requirements of CD45 protein tyrosine phosphatase for cytolytic activities and intrathymic and extrathymic development of intestinal intraepithelial lymphocytes

CD45 is a transmembrane protein tyrosine phosphatase essential for Ag receptor-mediated signaling in both T and B cells. In this study we investigated roles of CD45 in development and cytolytic activities of murine intestinal intraepithelial lymphocytes (i-IEL) using CD45 exon 6 knockout (CD45-/-) mice. Interestingly, the total cell number of i-IEL was significantly reduced in CD45-/-mice during aging (10-20 wk of age), whereas the i-IEL number was normally increased in the wild-type littermates. Especially, the number of gamma(delta)TCR+ i-IEL decreased markedly in CD45-/- mice during aging. The i-IEL in CD45-/- mice were more susceptible to in vitro spontaneous apoptosis than the normal i-IEL, implying that CD45 is required for maintenance of the cellularity of i-IEL. Results from in vivo analyses of the extrathymic and intrathymic development of i-IEL suggested that CD45-mediated signaling is required for the intrathymic, but not the extrathymic, development of i-IEL. Moreover, the whole i-IEL from CD45-/- mice showed a significantly reduced cytolytic activity, and the residual cytolytic activity was completely diminished by depleting CD45+ i-IEL, suggesting that CD45 is indispensable for the TCR-mediated cytolytic activity of i-IEL. Furthermore, we found differential contributions of CD45 and p56lck to development and induction of cytolytic activities of i-IEL.     

Chromosomal damage in lymphocytes of controls and patients with autosomal and sex-chromosomal disorders

The frequency of chromosomal aberrations was studied in lymphocytes from karyotypically abnormal patients and normal donors. There was no difference between normal females and Down's syndrome female patients. Male Down's syndrome patients showed a significant increase in aberrations of normal diploid male lymphocytes and a significant difference was observed in male and female Down's syndrome patients. Sex-chromosomally abnormal patients, both X and Y chromosome deficient, showed elevated chromosomal aberrations compared with age and sex-matched normal diploid cells.     

A role for p21ras/MAP kinase in TCR-mediated activation of LFA-1

LFA-1 is a beta2 integrin that plays well-characterized roles in adhesion of T lymphocytes to APC, T cell-mediated cytolysis, and leukocyte-endothelial cell interactions. Although it is clear that LFA-1 must undergo affinity or avidity changes to bind its cellular ligand ICAM-1, the intracellular signaling pathways involved are not well characterized. Here, we show that the Ras-mitogen-activated protein kinase (MAPK) signaling pathway is also involved in TCR-activated LFA-1 adhesion. Expression of a dominant negative form of p21ras in a thymocyte cell line inhibits, while constitutively active p21ras both enhances and sustains, subsequent TCR-triggered adhesion to isolated ICAM-1. However, the Ras/MAPK pathway alone is not sufficient for activating T cell LFA-1, as inhibition of both downstream MAPK/extracellular regulated kinase kinase (MEK) activity and phosphatidylinositol 3-kinase activity is required for complete inhibition of adhesion.     

Biochemistry of antigen receptor signaling in mature and developing B lymphocytes

The function of the surface antigen receptor of B cells (BCR) has been extensively studied with respect to the activation of mature B lymphocytes. B cells at other points of development (e.g., pre-B cells, immature B cells, and germinal center B cells) also express forms of the BCR, and for cells at these developmental timepoints, signaling through the BCR in some cases may lead to outcomes other than B-cell activation. Understanding the molecular events that are initiated by BCR crosslinking would enhance our understanding of the regulation and functional results of BCR signaling throughout B-cell development. In this article we review the current understanding of BCR signal transduction from initiation of the signal through changes in expression of genes that regulate the activation state. Costimulatory and modulatory molecules are considered with regard to their ability to affect the sensitivity or outcome of the BCR signal. Finally, we discuss how BCR signal transduction and the results of BCR signaling may differ at distinct stages in B-cell development.     

Increased reactivity to endothelin of pulmonary arteries in long-term post-obstructive pulmonary vasculopathy in rats

Some sigma receptor ligands have been shown to bind with low affinity to the dopamine transporter and to inhibit [3H]dopamine uptake. It has not previously been shown whether any of these compounds influence release of dopamine via facilitated exchange diffusion. To further examine the nature of the interaction between sigma receptor ligands and the dopamine transporter, the effects of sigma receptor ligands on amphetamine-stimulated [3H]dopamine release were examined in slices prepared from rat caudate putamen. In the absence of exogenous Ca2+, both (+)-pentazocine and (-)-pentazocine potentiated amphetamine-stimulated [3H]dopamine release at concentrations consistent with their affinities for sigma2 receptors. In contrast, BD737 (1S.2R-(-)-cis-N-?2-(3,4-dichlorophenyl)ethyl?-N-methyl-2-(1-pyrrolidiny l)cyclohexylamine), a sigma1 receptor agonist, had no effect on amphetamine-stimulated release. Neither isomer of pentazocine alone had any effect on basal [3H]dopamine release under these conditions. Three antagonists at sigma receptors, one of which is non-selective for subtypes, and two of which are sigma2-selective, all blocked the enhancement of stimulated release produced by (+)-pentazocine. Enhancement of stimulated release by (-)-pentazocine was similarly blocked by sigma2 receptor antagonists. Our data support the contention that it is possible to regulate transporter-mediated events with drugs that act at a subpopulation of sigma receptors pharmacologically identified as the sigma2 subtype.     

Fas ligand-mediated lysis of self bystander targets by human papillomavirus-specific CD8+ cytotoxic T lymphocytes

Mouse cytotoxic T lymphocytes (CTL) reactive with a H-2Db-presented 9-mer peptide of the human papillomavirus type 16 protein E7(49-57) (RAHYNIVTF) were generated from the spleen cells of wild-type C57BL/6 (B6) or B6 perforin-deficient (B6.P0) mice. CD8(+) B6 CTL displayed peptide-specific perforin- and Fas-mediated lysis of E7-transfected mouse RMA lymphoma cells (RMA-E7), while CD8(+) CTL from B6.P0 mice lysed RMA-E7 cells via Fas ligand (FasL) exclusively. Rapid and efficient lysis of syngeneic bystander B6 blasts or RMA cells by either B6 or B6.P0 Ag-activated CTL was mediated by a FasL-Fas mechanism. Fas-resistant bystanders were not lysed, nor were allogeneic Fas-sensitive C3H/HeJ (H-2(k)) or BALB/c (H-2(d)) bystander blasts. Interestingly, however, phorbol myristate acetate-ionomycin preactivation of B6.P0 effectors enabled lysis of allogeneic H-2(k) and H-2(d) bystanders even in the absence of antigenic stimulation. Lysis of syngeneic bystander cells was always FasL-Fas dependent and required effector-bystander contact and, in particular, an interaction between CTL LFA-1 and bystander ICAM-1. Thus, in the context of major histocompatibility complex class I molecule-peptide ligation of the T-cell receptors of CD8(+) CTL, neighboring bystander cells that are syngeneic and Fas sensitive and express the adhesion molecule ICAM-1 are potential targets of CTL attack.     

Dose-rate sparing for micronucleus induction in lymphocytes of controls and ataxia-telangiectasia heterozygotes exposed to 60Co gamma-irradiation in vitro

We investigated the reproducibility of the cytochalasin B micronucleus (MN) assay in irradiated human lymphocytes to assess its suitability in predicting cancer predisposition and response to radiotherapy by virtue of defects in the processing of clastogenic lesions. G0 lymphocytes were exposed to 3.0 Gy 60Co gamma-rays at high (HDR) or low dose-rate (LDR). Six healthy donors were assayed three times each in nine experiments and compared with six ataxia-telangiectasia (A-T) heterozygotes. In controls, significant interexperiment variability in MN yields was observed at HDR and LDR, also in dose-rate sparing (i.e. reduction in MN yield at LDR compared with HDR). Significant inter-individual variability was seen at HDR, but not at LDR or for sparing. Average sparing was 66.4 +/- 4.8%. In spite of the experimental variability, a significant difference between controls and A-T heterozygotes was detected at LDR, and 5/6 heterozygotes had sparing values below the control range. This gives encouragement for the use of this assay in predictive testing if sources of experimental variability can be identified so as to improve discrimination between individuals. HDR and to a lesser extent LDR irradiation induced significant mitotic inhibition, seen as a reduction in binucleate cells after cytocholasin treatment. A positive correlation between mitotic inhibition and MN frequency suggests that similar lesions may be involved in these effects.     

Interactions of lymphocytes from patients with psoriatic arthritis or healthy controls and cultured endothelial cells

Psoriatic arthritis (PA) is an inflammatory rheumatic disease that can concomitantly occur in patients with psoriasis vulgaris. Psoriatic synovitis shows alterations of the synovial microvasculature. Inflammatory cells adhere to endothelial cells (EC) and migrate through the vascular wall of postcapillary venules located in the subintimal layer of the synovial membrane. The aim of our study was to investigate, first, the phenotype of lymphocytes (LC) of PA patients using flow cytometry (FC) with regard to activation antigens and adhesion molecules; second, the adhesion of LC of PA patients on cultivated resting or activated (with thrombin, LPS, IFN-gamma, or TNF-alpha) human umbilical vein endothelial cells (HUVEC) by counting the Feulgen-stained nuclei of both adherent LC and HUVEC using image analysis; and third, the synthesis of IL-6 and IL-8 in both LC and HUVEC 24 hr after cell contact. These cytokines were determined qualitatively by immunofluorescence and quantitatively at the single-cell level by FC as well as in the supernatants of the cultures using commercial cytokine ELISAs. Fourth, we investigated whether or not the LC adhesion on HUVEC as well as the cytokine production could be inhibited by monoclonal antibodies against LC- or EC-specific adhesion molecules. In contrast to controls PA patients showed an increased surface expression of CD11a, b, and c as well as of CD44 but a reduced surface expression of CD49d/CD29, and CD49e/CD29, and cell-bound fibronectin on CD3+ LC. The activation markers CD25 and HLA-DR were found to be slightly enhanced in PA. The cell adhesion was generally enhanced in PA patients vs controls. It could be reduced with monoclonal antibodies (MoAbs) against CD11a and CD18 on IFN-gamma- or TNF-alpha-activated HUVEC but was generally enhanced after treatment of HUVEC with MoAbs against CD54, CD62E, or CD106. Due to LC adhesion on HUVEC IL-6 and IL-8 were produced in significantly higher amounts in PA patients compared to controls. This effect occurred already in resting but was enhanced in activated HUVEC. While IL-6 is mainly produced by HUVEC but also in smaller quantities by LC, IL-8 is synthesized only by HUVEC and could be modified by preincubation with MoAbs against LC- or EC-specific adhesion molecules in parallel to the cell adhesion. The experiments show that the main adhesion pathway in LC homing of PA patients is the interaction of the LC adhesion molecule CD11a/CD18 with CD54 on EC followed by an enhanced synthesis of proinflammatory and chemotactic cytokines. These results favor the hypothesis that the pathological alterations of the microvasculature in PA patients are generated by altered homing processes.