Automated phonological analysis and treatment target selection using AutoPATT

Automated analyses of speech samples can offer improved accuracy and timesaving advantages that streamline clinical assessment for children with a suspected speech sound disorder. In this paper, we introduce AutoPATT, an automated tool for clinical analysis of speech samples. This free, open-source tool was developed as a plug-in for Phon and follows the procedures of the Phonological Analysis and Treatment Target Selection protocol, including extraction of a phonetic inventory, phonemic inventory with corresponding minimal pairs, and initial consonant cluster inventory. AutoPATT also provides suggestions for complex treatment targets using evidence-based guidelines. Automated analyses and target suggestions were compared to manual analyses of 25 speech samples from children with phonological disorder. Results indicate that AutoPATT inventory analyses are more accurate than manual analyses. However, treatment targets generated by AutoPATT should be viewed as suggestions and not used to substitute necessary clinical judgement in the target selection process.

A phase II study of a 5T4 oncofoetal antigen tumour-targeted superantigen (ABR-214936) therapy in patients with advanced renal cell carcinoma

In a phase II study, 43 renal cell carcinoma patients were treated with individualised doses of ABR-214936; a fusion of a Fab recognising the antigen 5T4, and Staphylococcal enterotoxin A. Drug was given intravenously on 4 consecutive days, treatment was repeated 1 month later. Treatment was associated with moderate fever and nausea, but well tolerated. Of 40 evaluable patients, 28 had disease control at 2 months, and at 4 months, one patient showed partial response (PR) and 16 patients stable disease. Median survival, with minimum follow-up of 26 months was 19.7 months with 13 patients alive to date. Stratification by the Motzer's prognostic criteria highlights prolonged survival compared to published expectation. Patients receiving higher drug exposure had greater disease control and lived almost twice as long as expected, whereas the low-exposure patients survived as expected. Sustained interleukin-2 (IL-2) production after a repeated injection appears to be a biomarker for clinical effect, as the induced-IL-2 level on the day 2 of treatment correlated with survival. The high degree of disease control and the prolonged survival suggest that this treatment can be effective. These findings will be used in the trial design for the next generation of drug, with reduced antigenicity and toxicity.

An open label phase I study of ABR-217620, a fusion protein of the 5T4 antibody moiety and an engineered superantigen, in patients with non-small cell lung, renal cell or pancreatic cancer

3083

Background: ABR-217620 (naptumomab estafenatox) is a recombinant fusion protein that consists of the 5T4Fab moiety genetically fused to the engineered superantigen variant SEA/E-120. This fusion protein is a new generation tumor-targeted superantigen based on the previously described ABR-214936 (anatumomab mafenatox). ABR-217620 was designed to reduce antigenicity and toxicity. The 5T4 antigen is expressed on more than 95 % of tumors from patients with non-small cell lung (NSCLC), renal cell (RCC) and pancreatic cancer (PC). In clinical PET studies 124I-labeled ABR-217620 has been shown to localize to 5T4 positive tumors. Methods: The compound was administered as a 5 min bolus infusion for 5 consecutive days. Patients with disease control at day 28 were offered a second cycle of therapy. Dose escalation has been performed using a Bayesian model starting at 0.5 μg/kg/day. The primary endpoint is determination of MTD. Secondary endpoints include characterization of side effects, immunological response, efficacy and pharmacokinetics. Results: 31 patients to date have been treated (19 NSCLC, 8 RCC, 4 PC). 3 patients have had dose limiting toxicities (fever, hypotension and nausea, grade 3) at doses between 23 and 28 μg/kg/day. The side effects were resolved quickly. Based on the experience from ABR-214936, these side effects were expected, but the MTD is ∼ 200 times higher. ABR-217620 leads to a dose dependent systemic increase of cytokines including IL-2 and IFN-γ after infusion. It also leads to an expansion of the superantigen reactive T cell population. 16/29 evaluable patients investigated had SD while 13 patients had PD. In contrast to ABR-214936, the first cycle of ABR-217620 treatment can be given without factoring in the titer of preformed anti-superantigen antibodies. Conclusions: ABR-217620 treatment had predicted and manageable side effects with fever, hypotension and nausea being dose limiting toxicities. Treatment with ABR-217620 resulted in a restricted systemic activation of the immune system. A large fraction of the patients have had stable disease.

[Table: see text]

Linomide and Antibody-Targeted Superantigen Therapy Abolishes Formation of Liver Metastases in Mice

Hematogenous spread of tumor cells and metastasis formation in the liver are insidious aspects of cancer progression and are not frequently amenable to curative treatment. We examined the effect of Linomide and antibody-targeted therapy against the formation of hepatic metastases in vivo. For this purpose, syngenic B16 melanoma cells transfected with GA733-2 (a human colon cancer cell surface antigen) were injected into a mesenteric vein of C57/Bl6 mice. To test bacterial superantigen (Sag) targeting for immunotherapy of liver metastases, we used genetically fused proteins consisting of SEA and a Fab moiety of a GA733-2 tumor-reactive antibody (C215Fab-SEA). Linomide dose-dependently reduced hepatic metastases, and at 300 mg/kg this reduction was more than 80%. Treatment with C215Fab-SEA decreased metastases formation by 49% and the combination of Linomide and C215Fab-SEA was found to completely abolish liver metastases (>99% reduction). Taken together, our novel data suggest that Linomide and antibody-targeted superantigen therapy individually markedly reduce and together abolish liver metastases. Considering that current therapy of hepatic metastases is mainly limited to surgical resection in a subgroup of patients, these findings indicate that Linomide alone or in combination with antibody-targeted superantigen may provide a novel approach against liver metastases.

Roquinimex inhibits dextran sodium sulfate-induced murine colitis

OBJECTIVE

Roquinimex is a modulator of the immune system and has been shown to attenuate induction of several inflammatory and autoimmune diseases. The objective of the present study was to determine the efficacy of roquinimex in a model of murine colitis.

MATERIALS AND METHODS

For this purpose, Balb/c mice were exposed to 5% dextran sodium sulfate (DSS) in the drinking water for five to six days. Roquinimex (300 mg kg(-1) day(-1)) was administered by subcutaneous (s.c.) injection 3 days prior to and throughout the treatment period with DSS. In separate experiments, 300 mg kg(-1) day(-1) of roquinimex was given therapeutically after initiation of DSS challenge.

RESULTS

DSS provoked clinical signs of colitis, reduced crypt height (CH) and increased mucosal damage score (MDS) as analyzed by histology. In addition, challenge with DSS increased the colonic content of myeloperoxidase (MPO). Prophylactic administration of DSS-treated mice with roquinimex significantly reduced clinical signs of colitis, MDS and the CH-reduction. Moreover, in roquinimex treated animals, the MPO activity was significantly reduced by more than 50% compared to DSS control mice. Notably, therapeutic administration of roquinimex in DSS-treated mice also significantly inhibited the MDS, CH-reduction and MPO activity.

CONCLUSIONS

These findings suggest that roquinimex strongly inhibits murine colitis and may provide a novel pharmacological approach to treat inflammatory bowel disease.

Suppression of experimental autoimmune neuritis by ABR-215062 is associated with altered Th1/Th2 balance and inhibited migration of inflammatory cells into the peripheral nerve tissue

The therapeutic effects of ABR-215062, which is a new immunoregulator derived from Linomide, have been evaluated in experimental autoimmune neuritis (EAN), a CD4(+) T cell-mediated animal model of Guillain-Barré syndrome in man. In previous studies, we reported that Linomide suppressed the clinical EAN and myelin antigen-reactive T and B cell responses. Here EAN induced in Lewis rats by inoculation with peripheral nerve myelin P0 protein peptide 180-199 and Freund's complete adjuvant was strongly suppressed by ABR-215062 administered daily subcutaneously from the day of inoculation. ABR-215062 dose-dependently reduced the incidence of EAN, ameliorated clinical signs and inhibited P0 peptide 180-199-specific T cell responses as well as also the decreased inflammation and demyelination in the peripheral nerves. The suppression of clinical EAN was associated with inhibition of the inflammatory cytokines IFN-gamma and TNF-alpha, as well as the enhancement of anti-inflammatory cytokine IL-4 in lymph node cells and periphery nerve tissues, respectively, in a dose-dependent manner. These effects indicate that ABR-215062 may mediate its effects by regulation of Th1/Th2 cytokine balance and suggest that ABR-215062 is potentially a new chemical entity for effective treatment of autoimmune diseases.

The immunomodulator Linomide: role in treatment and prevention of autoimmune diabetes mellitus

Insulin-dependent diabetes mellitus (IDDM) is considered to be an autoimmune disorder characterized by destruction of the pancreatic beta-cells by auto-reacting lymphocytes. An attractive therapeutic approach to this disease would be to abrogate the autoimmune process at an early stage, thus preserving a critical mass of pancreatic beta-cells necessary for maintenance of normal glucose tolerance. Linomide (quinoline-3-carboxamide, Roquinimex, LS 2616), is a novel, orally absorbed, immunomodulatory drug that has been shown to be effective in various models of autoimmunity without causing non-specific immunosuppression. In this review, we describe the efficacy of Linomide for ameliorating the autoimmune process and diabetes in the non-obese diabetic (NOD) model of IDDM when administered at early stages of the disease. We also show that advanced disease in the NOD mouse can be treated effectively by combining Linomide with therapeutic modalities designed to increase pancreatic beta-cell mass. Subsequent clinical studies have shown that Linomide preserves beta-cell function in individuals with new-onset IDDM. Based on these data, Linomide or derivatives thereof might be useful for treatment of human IDDM.

Effects of Linomide on immune cells and cytokines inhibit autoimmune pathologies of the central and peripheral nervous system

Linomide (roquinimex, LS 2616) is a quinoline-3-carboxamide with pleiotropic immune modulating capacity and it has therapeutic effects in several experimental animal models of autoimmune diseases. Linomide has been evaluated in clinical trials for multiple sclerosis, and was indeed shown to have disease inhibitory effects. However, due to unexpected side effects recorded in patients treated with Linomide, premature termination of clinical trials was required. The basic mechanism(s) of action of Linomide in inducing beneficial effects in autoimmune diseases is still elusive. Some experimental evidence indicates that Linomide influences the regulation of the cytokine profile, resulting in the inhibition of autoimmune and inflammation pathologies. This review focuses on Linomide applied in models for autoimmune and inflammation pathologies of the central and the peripheral nervous system, and summarises its very encouraging disease inhibitory effects and their potential pharmacological basis. The beneficial effects recorded with Linomide in both experimental and clinical trials emphasise the possible value of substances with Linomide-like activity for clinical use in autoimmune and inflammation pathologies in the near future.

Linomide abolishes leukocyte adhesion and extravascular recruitment induced by tumor necrosis factor alpha in vivo

The immunomodulator Linomide (roquinimex) ameliorates the development of numerous inflammatory and immunological diseases, including sepsis, arthritis, and encephalomyelitis. However, the mechanism underlying this protective effect of Linomide remains unclear. In this study, we wanted to evaluate the effect of Linomide treatment on the different steps in the extravasation process of leukocytes stimulated by tumor necrosis factor alpha (TNF-alpha) in vivo. For this purpose, we used intravital microscopy in the mouse cremaster muscle microcirculation. We found that pretreatment with Linomide dose-dependently (3-300 mg/kg) reduced TNF-alpha-induced leukocyte adhesion and tissue recruitment. Notably, at 300 mg/kg response to TNF-alpha was nearly abolished, i.e. leukocyte adhesion was decreased by 83% and recruitment by 86%. In fact, the anti-inflammatory effect of this dose of Linomide corresponded in magnitude to the potency of 10 mg/kg of dexamethasone. Moreover, administration of Linomide did not alter the systemic leukocyte counts. On the other hand, 1-10 mg/kg of dexamethasone decreased the circulating number of mononuclear leukocytes by 77%. Taken together, our novel findings demonstrate that Linomide is a potent inhibitor of leukocyte adhesion and recruitment in cytokine-activated tissues. These data may help explain the documented protection provided by Linomide in inflammatory diseases characterized by cytokine and leukocyte accumulation.

Inhibition of autoimmune disease by the immunomodulator linomide correlates with the ability to activate macrophages

Linomide is a potent immunomodulator that has been shown to inhibit autoimmunity in several animal models of autoimmune disease, including experimental autoimmune encephalomyelitis (EAE). Linomide's mechanism of action is unknown, however, it has been suggested to modulate the function of antigen presenting cells (APC) and that this may account for the inhibition of autoimmune disease. In this study we have been able to show that Linomide treatment of SJL/N mice upregulates the cell surface expression of several activation markers on macrophages and B cells. Thus, we found the following markers, expressed as a % of control, to be significantly upregulated following Linomide treatment; MHC class II (260%), Ly-6A/E (520%), CD11a (280%), CD54 (190%) and CD80 (200%) on macrophages and Ly-6A/E (250%) and CD11a (150%) on B cells. The duration and dosage of Linomide required to obtain these effects is similar to those required for EAE inhibition. Several Linomide analogues were made by the introduction of structural modifications into the Linomide molecule, resulting in a number of compounds with varying effects on EAE. We found a linear relationship between the compound's ability to inhibit EAE and its ability to upregulate MHC class II on macrophages (p<0.001), such that compounds which were able to inhibit EAE also upregulated MHC class II expression, whereas those that did not inhibit EAE were unable to do so. These results suggest that drug-mediated activation of distinct APC functions may be protective in autoimmunity.

Self-MHC class Ia (RT1-A(n)) protects cells co-expressing the activatory allogeneic MHC class Ib molecule (RT1-E(u)) from NK lysis

We have previously shown activation of NK cells via recognition of an allogeneic, non-classical MHC class I molecule, RT1-E(u). In this study we investigated whether a self-MHC class I molecule could protect the allogeneic targets from being recognized and killed by the alloreactive NK (allo NK) cells. NK cells from BN (RT1 n) rats, primed in vivo by immunization with RT1(u)-expressing cells, manifested cytolytic activity against RT1(u)- as well as RT1(u/lv1)-expressing targets, but not against RT1(u/n)-expressing targets. The absence of cytolytic activity against semiallogeneic targets, i.e. targets expressing self-allotypes, was also valid for allo NK cells from alloimmunized F344 (RT1 (lv1)) rats. To analyze the ability of a distinct MHC class I molecule to protect target cells from NK lysis, Rat2 cells transfected with the activating allogeneic MHC class Ib, RT1-E(u) molecule were also transfected with the self-MHC class Ia, RT1-A1(n) molecule. The allo NK cells from BN rats immunized with RT1(u)-expressing cells were cytolytic against Rat2 transfected with the RT1-E(u) molecule. However, the allo NK cells manifested no cytolytic activity against double-transfected Rat2 cells, expressing the RT1-E(u) as well as the RT1-A1(n) molecule. We conclude that expression of a self-MHC class Ia (RT1-A) molecule protects targets from allo NK killing. Furthermore, the NK inhibition via recognition of the self-MHC class Ia molecule dominates over the activation via recognition of the allogeneic MHC class Ib molecule, RT1-E.

Low CD86 expression in the nonobese diabetic mouse results in the impairment of both T cell activation and CTLA-4 up-regulation

The nonobese diabetic (NOD) mouse spontaneously develops autoimmune insulin-dependent diabetes mellitus and serves as a model for human type I diabetes. NOD spleen cells proliferate to a lesser extent than those from C57BL/6 and BALB/c mice in response to anti-CD3. To investigate the cause of this reduced T cell proliferation, costimulatory molecule expression was investigated. It was found that NOD macrophages, dendritic cells, and T cells, but not B cells, expressed lower basal levels of CD86, but not CD80, CD28, or CD40, compared with C57BL/6 and BALB/c. This low CD86 expression was not dependent on the MHC haplotype or on diabetes development since the NOD-related, diabetes-free mouse strains NON (H-2nb1) and NOR (H-2g7) exhibited similar low levels of CD86 expression and proliferation. Furthermore, following activation, the relative up-regulation of CTLA-4, as compared with CD28, was more pronounced on C57BL/6 and BALB/c T cells as shown by an increased CTLA-4/CD28 ratio. This activation-induced increase in the CTLA-4/CD28 ratio was markedly reduced on NOD T cells compared with the other two strains. The low CD86 expression in NOD mice may account for the reduced increase in both proliferation and the CTLA-4/CD28 ratio, since reducing CD86 expression in C57BL/6 and BALB/c cultures to NOD levels significantly reduces the proliferation and the CTLA-4/CD28 ratio. Therefore, we propose that a low level of CD86 expression in the NOD mouse contributes to a defective regulation of autoreactive T cells by preventing the full activation of T cells and therefore the up-regulation of CTLA-4.

Activation and selection of NK cells via recognition of an allogeneic, non-classical MHC class I molecule, RT1-E

Previous studies have established that NK cells express both inhibitory and activatory receptors. The inhibitory receptors have been shown to recognize major MHC class I molecules, but the physiological ligands for the activatory receptors have been only partly characterized. In this study we investigated whether NK cells could be activated by recognizing specific non-classical MHC class Ib molecules. NK cells from BN (RT1(n)) rats immunized in vivo with MHC-incompatible WF (RT1(u)) cells displayed cytolytic activity specific for product(s) of the MHC class Ib RT1-E(u) / C(u) region. These cells were shown to kill Rat2 fibroblast cells transfected with cDNA for RT1-E(u) but neither untransfected Rat2 nor a transfectant with the class Ia allele, RT1-A(u). Cytolysis of Rat2-RT1-E(u) was inhibited by the anti-RT1-E(u) antibody 70-3-C2. In addition, NK cells cytolytic against PVG (RT1(c)) targets, but not against WF (RT1(u)) or other allogeneic targets were activated after PVG immunization of BN rats. The generation of NK populations cytolytic for target cells of the same haplotype as the immunizing cells, but not for third-party targets, strongly suggests the existence of a selective NK-mediated response in vivo. We conclude that recognition of an allogeneic MHC class Ib RT1-E molecule activates NK cells and the specific cytolytic response could be regarded as adaptive.

Proliferation and differentiation of alloselective NK cells after alloimmunization-evidence for an adaptive NK response

We have previously demonstrated the activation of NK cells exhibiting RT1 allele-specific cytolytic activity following intraperitoneal immunization of certain rat strains with allogeneic cells. In the present study, we show that the NK allocytolytic activity in BN (RT1(n)) rats immunized with WF (RT1(u)) cells was associated with an increased proportion of peritoneal, as well as splenic, NK cells. Furthermore, the proliferation of NK cells was substantially increased in BN (RT1(n)) rats immunized with WF (RT1(u)) cells when compared to that in naive BN rats. In addition, the NK subpopulation exhibiting the allocytolytic activity in alloimmunized rats exhibited a decreased expression of the NKR-P1 and L-selectin molecules, but an increased expression of the LFA-1 molecule when compared to NK cells from naive rats. Thus, we have shown that the existence of peritoneal NK cells, exhibiting selective allocytolytic activity in alloimmunized rats, is probably due to a combination of RT1 allele-selective recruitment, proliferation, and the differentiation of NK cells. Therefore, in the same way that we regard T cells as being capable of adapting the immune response, this study presents evidence for the hypothesis that the specific cytolytic response of alloreactive NK cells should also be regarded as adaptive.

Central venous catheter motion: a pitfall in catheter localization on pediatric chest radiography

OBJECTIVE

We evaluated central venous catheter motion causing misinterpretation of catheter tip location in pediatric patients and in an experimental model.

MATERIALS AND METHODS

After the recognition of clinically significant catheter motion in 12 randomly selected patients, we conducted a prospective 2-month study of chest radiographs in our pediatric care unit and neonatal emergency department. Serial radiographs were examined for change in catheter tip position ascribed to motion artifact. An in vitro model was developed to replicate clinical parameters. Experimentally, catheter movement and exposure time were analyzed and their impact on catheter localization was recorded.

RESULTS

In the 12 randomly selected patients, radiographic assessment of central venous catheter tip localization on sequential radiographs caused minor to major misinterpretation of the position of the catheter tip and even total nonvisualization of the catheter. Ten (3.5%) of 352 prospectively interpreted pediatric emergency department radiographs showed similar findings. Catheter motion that caused blurring was reproduced in vitro using radiographic parameters typically used in a clinical setting.

CONCLUSION

Catheter motion can cause problems in assessing catheter tip position on pediatric emergency department chest radiographs. We reproduced this phenomenon in an in vitro model. Catheter removal or change in position may be mimicked by this artifact, and patient management may be affected. In our study, catheter localization was affected by catheter motion and exposure time.

Effect of the synthetic immunomodulator, linomide, on experimental models of thyroiditis

The drug Linomide is an immunomodulator showing marked down-regulation of several experimental autoimmune diseases. In this study, its effect on three different experimental models of thyroid disease and on spontaneous infiltration of salivary glands (sialoadenitis), was investigated. Although very effective at preventing thyroid infiltrates in mice immunized with mouse thyroglobulin and complete Freund's adjuvant and in spontaneous models of thyroiditis and sialoadenitis, it completely failed to modify experimental autoimmune thyroiditis (EAT) induced in mice immunized with mouse thyroglobulin and lipopolysaccharide. There was no significant shift in the observed isotypes of anti-mouse thyroglobulin antibodies and only anti-mouse thyroglobulin antibodies in the spontaneous model were completely down-modulated by the drug. One surprising fact to emerge was that Linomide-treated donor mice, although protected from thyroid lesions themselves, were still able to transfer EAT showing that they must have been effectively primed while being treated with Linomide. It is possible that the drug down modulated EAT by interfering with the trafficking of primed effector cells.

The inhibitory effect in experimental autoimmune encephalomyelitis by the immunomodulatory drug Linomide (PNU-212616) is not mediated via release of endogenous glucocorticoids

The immunomodulatory drug Linomide (PNU-212616) is an efficient inhibitor of experimental autoimmune encephalomyelitis (EAE) and a variety of other models of autoimmunity. The mechanism of action of the drug is, however, incompletely resolved. It was recently suggested that Linomide might exert its immunomodulatory activity by stimulation of the hypothalamic-pituitary-adrenal axis. To investigate the relevance of this mechanism of action, we monitored the plasma levels of endogenous corticosterone after treatment with Linomide, and also directly compared the inhibitory activity of the drug on acute EAE induced in sham or adrenalectomized SJL/N mice. Treatment with Linomide resulted in a dose related inhibition of EAE in line with previously reported results. Upon onset of clinical signs of EAE, there was a 7-10 fold elevation of plasma corticosterone from the normal baseline level. Administration of Linomide did however not by itself result in any change in plasma corticosterone levels, neither at the pre-symptomatic phase of the disease nor during acute short term treatment. In adrenal ectomized animals immunized for EAE, paralytic disease developed rapidly and was of a more severe and fatal nature as compared to sham-operated controls. Treatment with Linomide had a profound inhibitory effect on development of paralytic disease in both the ectomized and sham-operated groups. These results strongly suggest that Linomide does not exert its immunomodulatory activity via the release of endogenous glucocorticoids.

Linomide suppresses experimental autoimmune neuritis in Lewis rats by inhibiting myelin antigen-reactive T and B cell responses

Linomide (quinoline-3-carboxamide) is a synthetic immunomodulator that suppresses several experimental autoimmune diseases. Here we report the effects of Linomide on experimental autoimmune neuritis (EAN), a CD4+ T cell-mediated animal model of acute Guillain-Barré syndrome (GBS) in humans. EAN induced in Lewis rats by inoculation with bovine peripheral nervous system (PNS) myelin and Freund's complete adjuvant was strongly suppressed by Linomide administered daily subcutaneously from the day of inoculation. Linomide dose-dependently delayed the interval between immunization and onset of clinical EAN, as well as the severity of EAN symptoms. These clinical effects were associated with dose-dependent down-modulation of PNS antigen-induced T and B cell responses and with suppression of the proinflammatory cytokines IL-12, interferon-gamma (IFN-gamma) and tumour necrosis factor-alpha (TNF-alpha) mRNA. In PNS sections, Linomide suppressed IL-12 and TNF-alpha, and up-regulated IL-10 mRNA expression. These findings suggest that Linomide could be useful in certain T cell-dependent autoimmune diseases.

Activation of donor-specific CTL in a tolerant recipient of cardiac allograft

Permanent graft acceptance was induced with cyclosporine A in a low responder rat strain combination PVG (RT1(c)) to DA (RT1(av1)) of cardiac transplants. Challenge (alloimmunization) with donor and third-party WF (RT1(u)) cells was performed and followed by the analysis of alloreactive cytotoxicity. The cytotoxic T lymphocytes (CTL) from recipients with permanently accepted cardiac grafts manifested cytolytic activity against third-party target cells but not against donor target cells. The findings demonstrated unresponsiveness to be donor-specific, i.e., transplant tolerance was present. This was verified by retransplantation of the DA recipient with either a second PVG heart (which was accepted) or a third-party (WF) heart (which was rejected). Restoration of donor-specific CTL after injection of exogeneous interleukin(IL)-2 concomitant with challenge showed that the donor-specific CTL were not depleted, but unable to be activated as a consequence of IL-2 deficiency. Despite donor-specific CTL activation in vivo the recipients failed to reject their established grafts, implying an ongoing presence of suppression.

Linomide suppresses chronic-relapsing experimental autoimmune encephalomyelitis in DA rats

Linomide (quinoline-3-carboxamide) is a synthetic immunomodulator that suppresses several experimental autoimmune diseases. Here we report the effects of Linomide on chronic progressive and/or relapsing experimental autoimmune encephalomyelitis (PR-EAE), a CD4+ T cell mediated animal model of multiple sclerosis (MS). PR-EAE induced in DA rats by inoculation with homogenized guinea pig spinal cord and Freund's complete adjuvant, was strongly suppressed by Linomide administered daily subcutaneously from the day of inoculation. Linomide dose-dependently delayed the interval between immunization and onset of clinical PR-EAE, reduced severity and relapse of clinical PR-EAE, and shortened clinical PR-EAE. These clinical effects were associated with the down-modulation of CNS antigen-induced T cell responses and production of proinflammatory cytokines (IFN-gamma and TNF-alpha) as well as with upregulation of IL-4 (except in spleen MNC), IL-10 and TGF-beta in both spleen MNC and the spinal cord. These effects indicate that Linomide can suppress PR-EAE and may mediate its suppressive effects by regulation of cytokines.

ICAM-1 costimulation induces IL-2 but inhibits IL-10 production in superantigen-activated human CD4+ T cells

We have previously reported that costimulatory pathways including B7-CD28 and lymphocyte function-associated antigen-3 (LFA-3)-CD2 shape distinct activation profiles in human CD4+ T cells. We now show that superantigen (SAg), in combination with intracellular adhesion molecule-1 (ICAM-1) costimulation drives a proliferative response accompanied by high levels of interleukin-2 (IL-2) and moderate levels of interferon-gamma (IFN-gamma) and tumour necrosis factor (TNF). This response profile differs from that observed in B7 or LFA-3 costimulated T cells because our previous results showed that B7-CD28 costimulation was accompanied by high levels of IL-2, IFN-gamma and TNF, whereas LFA-3 was a potent inducer of IFN-gamma and TNF, but had little influence on IL-2 production. The ICAM-1-induced IL-2 production could efficiently be abrogated with monoclonal antibody (mAb) against ICAM-1 or LFA-1, showing that the activation is dependent of a functional ICAM-1-LFA-1 pathway. SAg-induced IL-2, IFN-gamma and TNF were detected in both CD4+ and CD8+ T cells, whereas production of IL-10 was restricted to CD4+ T cells. A major finding in the present study was that ICAM-1 costimulation strongly inhibits IL-10 production in CD4+ T cells. Our data demonstrate that ICAM-1 costimulation is sufficient to induce large amounts of IL-2. The presence of ICAM-1 results in suppression of IL-10 production in T helper (Th) cells, which may favour the development of Th1 and not Th2 T cells.

Linomide (roquinimex) affects the balance between pro- and anti-inflammatory cytokines in vitro in multiple sclerosis

OBJECTIVES

Multiple sclerosis (MS) is characterized by high levels of circulating mononuclear cells (MNC) that respond to myelin proteins like myelin basic protein (MBP) in vitro by expressing mRNA of both pro-inflammatory cytokines, e.g. interferon-gamma (IFN-gamma), tumor necrosis factor-alpha (TNF-alpha) and lymphotoxin (LT) that may make MS worse, and anti-inflammatory cytokines like IL-4, IL-10 and transforming growth factor-beta (TGF-beta) that may act beneficially. Substances that down-regulate cytokines such as TNF-alpha or promote IL-10 or TGF-beta can be anticipated to affect MS beneficially.

MATERIAL AND METHODS

In situ hybridization to detect and enumerate IFN-gamma, TNF-alpha, LT, IL-4, IL-10 and TGF-beta mRNA expressing blood MNC after stimulation with myelin basic protein (MBP), control antigens and without antigen in presence and absence of Linomide (roquinimex, LS-2616) was employed. In parallel, ELISPOT assay to detect MBP- and PHA-reactive IFN-gamma secreting blood MNC+/-Linomide was used.

RESULTS

Here we report that Linomide, a synthetic immunomodulator, at concentrations effective in vivo reduces the number of MBP-reactive TNF-alpha and increases MBP-reactive IL-10 and TGF-beta mRNA expressing MNC from MS patients' blood when analysed in vitro. Compared to dexamethasone, Linomide up-regulated levels of blood MNC expressing mRNA of TGF-beta after culture in presence of MBP.

CONCLUSIONS

Changes of cytokine balance towards a production of anti-inflammatory cytokines could be a desirable effect to be evaluated in future drug studies of Linomide-like substances. At present, Linomide is not evaluable in MS clinical trials due to side-effects.

Linomide-mediated protection of oligodendrocytes is associated with inhibition of nitric oxide production and IL-1beta expression in Lewis rat glial cells

Linomide is a synthetic immunomodulator that down-regulates autoimmune response without inducing systemic immunosuppression. Linomide effectively inhibits severe experimental autoimmune diseases, like experimental allergic encephalomyelitis (EAE), a model of multiple sclerosis (MS). Here we report that Linomide suppresses nitric oxide (NO) production by microglia and astrocytes derived from newborn rats and prevented oligodendrocyte damage. Linomide strongly inhibited interleukin (IL) 1 betamRNA expression on glial cells, suggesting a potential mechanism for inhibition of NO production by Linomide. These results demonstrate that Linomide-mediated inhibition of NO production by glial cells could explain the preventive and therapeutic effects of Linomide in EAE and perhaps also MS. However, Linomide at higher dose [correction of doss] (10(-5) M) resulted in direct oligodendrocyte damage.

Overexpression of p65 and c-Jun substitutes for B7-1 costimulation by targeting the CD28RE within the IL-2 promoter

The role of Rel and activation protein-1 (AP-1) in IL-2 promoter activity in B7-1- and leukocyte function-associated Ag-3 (LFA. 3)-costimulated T cells has been evaluated. We demonstrate that overexpression of c-Jun but not c-Fos increases IL-2 promoter activity in both B7-1- and LFA-3-costimulated Jurkat T cells. Cotransfection of both c-Jun and c-Fos substitutes for B7-1 costimulation in driving an activation protein-1 response element but not for the IL-2 promoter. Overexpression of Rel proteins demonstrated that p65-expressing Jurkat cells transcribed equally well a nuclear factor kappabeta reporter construct when costimulated with B7-1 or LFA-3, but transcription of IL-2 promoter or CD28 response element (CD28RE)-driven reporters was superior in B7-1-costimulated cells. Combined expression of c-Jun and p65 induced vigorous transcription of IL-2 promoter- and CD28RE-driven reporter constructs in both LFA-3- and B7-1-costimulated Jurkat cells. Mutating the CD28RE but not the upstream nuclear factor kappabeta-binding site in the IL-2 promoter reduced B7-1-driven transcription >90%. The results implicates a major role of the CD28RE in the integration of p65/c-Jun-mediated transcription within the IL-2 promoter. We suggest that the transition from an autocrine LFA-3-driven immune response to a B7--induced paracrine immune response involves the activation of c-Jun and p65, which target the CD28RE region of the IL-2 promoter.

Linomide suppresses acute experimental autoimmune encephalomyelitis in Lewis rats by counter-acting the imbalance of pro-inflammatory versus anti-inflammatory cytokines

Linomide (quinoline-3-carboxamide) is a synthetic immunomodulator that suppresses several experimental autoimmune diseases. Here we report the effects of Linomide on experimental autoimmune encephalomyelitis (EAE), a CD4+ T cell-mediated animal model of multiple sclerosis (MS). EAE induced in Lewis rats by inoculation with homogenized guinea pig spinal cord and Freund's complete adjuvant was strongly suppressed by Linomide administered daily subcutaneously from the day of inoculation. Linomide dose-dependently delayed the interval between immunization and onset of clinical EAE, and reduced severity of EAE symptoms. These clinical effects were associated with dose-dependent down-modulation of myelin antigens-induced T cell responses and by suppression of the proinflammatory cytokines IFN-gamma and TNF-alpha, and upregulation IL-4, IL-10 and TGF-beta as evaluated by in situ hybridization for mRNA expression in spleen mononuclear cells and spinal cord sections. These findings suggest that Linomide could be useful in certain T cell dependent autoimmune diseases.

The immune modulator Linomide prevents neuronal death in injured peripheral nerves of the mouse

Neuronal death after injury or disease could result from imbalanced cytokine expression. Linomide (LS-2616, quinoline-3-carboxamide), a synthetic immunomodulator with effects on cytokine production, suppresses autoimmune diseases of the nervous system. Here adult mice were pre-treated with 200 mg/kg/day of Linomide for 9 days, after which the sciatic nerves were crushed. After another 10 days of Linomide treatment the dorsal root ganglia were dissected out and stained for apoptosis, either immediately or after 2 days in culture, which increases cell death. Superior cervical ganglia were also cultured for 2 days. The Linomide pretreatment profoundly reduced (approximately 60-80%) the injury-induced apoptotic death of neurons and satellite cells in both systems. The results suggest that modulation of the inflammatory cytokine cascade is a promising road to nerve cell rescue.

Dendritic cells and macrophages are the first and major producers of TNF-alpha in pancreatic islets in the nonobese diabetic mouse

The nonobese diabetic (NOD) mouse spontaneously develops autoimmune insulin-dependent diabetes mellitus (IDDM) and serves as an animal model for human type I diabetes. TNF-alpha is known to be produced by islet-infiltrating mononuclear cells during insulitis and subsequent beta cell destruction and has been implicated in the pathogenesis of IDDM. Previously, T cells have been suggested as the main source of TNF-alpha in the islet infiltrate. However, on immunohistochemical analysis of TNF-alpha expression in islets, we are able to show that the staining pattern of TNF-alpha resembles that of dendritic cells (DC) and macrophages (Mphi) rather than T cells and that TNF-alpha is expressed in islets at the very early stages of insulitis when no T cells are detected. On double staining for TNF-alpha and cell surface markers, we can demonstrate that TNF-alpha staining clearly correlates with DC and Mphi, whereas there is a poor correlation with T cells. This feature was observed at both early and late stages of insulitis. TNF-alpha expression was also seen in NOD-SCID islets, in addition to a peri-islet infiltration consisting of DC and Mphi, indicating that T cells are not required for the early DC and Mphi infiltration and TNF-alpha expression in islets. In conclusion, our results show that DC and Mphi are the major, early source of TNF-alpha in the NOD islet infiltrate and that TNF-alpha can be expressed independently of T cells, indicating that the early DC and Mphi infiltration and expression of TNF-alpha are crucial in initiation of diabetes.

The effects of leflunomide and cyclosporin A on rejection of cardiac allografts in the rat

Leflunomide is a new low molecular weight immunosuppressive drug which inhibits the enzymes dehydroorotate-dehydrogenase and protein tyrosine kinase, both of which are important components in the immune response. As the mechanisms of action of leflunomide and cyclosporin A (CsA) are different, we postulated a synergistic effect of the two drugs and tested graft survival following leflunomide administration alone or in combination with CsA in a rat cardiac transplantation model. Low- and high-responder rat strain combinations were used in parallel and the experiments were performed both with and without challenge with Linomide, an immunomodulator which promotes graft rejection in this model. In the low-responder rat strain combination (Piebald Virol Glaxo graft to Dark Agouti recipient; PVG to DA), graft survival appeared to be a dichotomous variable, being characterized by tolerance or early rejection. Leflunomide (10 or 5 mg/kg) given for 10 days induced tolerance and CsA did likewise; the addition of Linomide abolished the immunosuppressive effect of leflunomide but not that of CsA. In the high-responder combination (DA to PVG), no tolerance was seen and graft survival was moderately prolonged both after leflunomide and after CsA treatment; the addition of Linomide to CsA or to leflunomide (5 mg/kg) abolished the immunosuppressive effect of the drugs. However, when CsA-Linomide or leflunomide-Linomide were supplemented with the second immunosuppressive drug, leflunomide or CsA respectively, graft survival was significantly prolonged (P < 0.001 in both cases). This suggests leflunomide and CsA have additive potential.

Linomide enhances apoptosis in CD4+CD8+ thymocytes

Linomide, a quinoline-3-carboxamide, has a pleiotropic immune modulating capacity and inhibits development as well as progression of disease in animal models of autoimmunity. Linomide treatment of mice resulted in a dramatic, dose-dependent decrease of the thymic cell number shortly after the start of administration. Flow cytometric analysis revealed that the major thymocyte subset, the early immature type CD4+CD8+ thymocytes, were reduced in number by 75%, mature CD4+CD8- or CD4-CD8+ thymocytes were less sensitive to treatment. The polyclonal T cell activator Con A (Concanavalin A) was used together with IL-2 to evaluate the potential proliferative responsiveness of ex vivo thymocytes. Thymocytes from mice treated with Linomide exhibited a more vigorous proliferation than control cultures. An effect shown to not only be due to the enrichment of mature thymocytes in the cultures from Linomide treated animals, but also when purified, mature thymocytes (CD4+CD8- and CD4-CD8+) were cultured with Con A and IL-2, these cells responded with a significantly enhanced proliferation. In vivo Linomide treatment did not result in increased plasma concentrations of corticosterone and treatment of adrenalectomized mice resulted in a reduction of thymocytes which was comparable to the effect in intact mice, indicating that glucocorticoids (GC) are not major mediators of Linomide-induced thymocyte deletion. In addition to this, and supporting a glucocorticoid independent mode of action, Linomide treatment of thymocytes in vitro resulted in a significant increase in the number of apoptotic cells, specifically in the CD4+CD8+ subset, implicating apopotosis as one component in the course of thymocyte reduction. In addition to this, in vivo treatment with Linomide resulted in an identical pattern to that seen in vitro in that there was significantly increased apoptosis only in the CD4+CD8+. These data indicate that Linomide modifies thymocyte development using a glucocorticoid independent pathway and results in the increased apoptosis of the CD4+CD8+ subset.

Selective cytotoxicity of two rodent T cell lymphomas to rat yolk sac tumours involves a retroviral envelope protein expressed by the lymphoma

A Gross virus induced rat T cell lymphoma G1-Tc1 and a Moloney virus induced mouse T cell lymphoma YAC-1 are shown to exert a strong cytotoxic activity against rat yolk sac tumours but not to various types of rat, mouse or human normal cells or tumour cell lines including carcinomas, sarcomas, lymphomas and gliomas. Both lymphomas are CD3+, CD4-, CD8- and T-cell receptor (TCR) alpha beta +. The cytotoxicity was not MHC restricted or dependent on the density of MHC class I of the target cells, and the mouse lymphoma killed the rat yolk sac tumour target. The cytotoxic action was fast and up to 80% specific killing was observed in 4-h 51Cr release assays. A rat B cell hybridoma was established from a Wistar/Furth (WF) rat immunized with the syngeneic lymphoma G1-Tc1 producing an immunoglobulin (Ig)G2c monoclonal antibody (MoAb) 1F2. This binds to the lymphomas G1-Tc1 and YAC-1 and also to a murine non-cytolytic Rauscher lymphoma RMA, but not to any other of several rat, mouse or human cell types tested. The 1F2 completely inhibited the killing of rat yolk sac tumours by the two cytolytic lymphomas, but did not interfere with the killing mediated by natural killer (NK) cells or cytolytic lymphokine-activated killer (LAK) cells. Immunochemical analysis of solubilized cell membranes of the lymphoma G1-Tc1 demonstrates that the 1F2 antibody recognizes an epitope on a retroviral gp 70 envelope protein. This indicates that a retroviral protein is involved in the lytic activity of the two lymphomas.

Linomide-induced suppression of experimental autoimmune neuritis is associated with down-regulated macrophage functions

Experimental autoimmune neuritis (EAN) is a T-cell mediated autoimmune disease of the peripheral nervous system, in which macrophages and T-cells feature prominently in nerve lesions. EAN represents a counterpart to Guillain-Barré syndrome in humans. In the present study, we investigated the in vitro and in vivo effects of Linomide (LS-2616, quinoline-3-carboxamide), a synthetic immunomodulatory compound, on macrophages in relation to EAN. Linomide strongly suppressed IFN-gamma and lipopolysaccharide (LPS)-induced IL-1 beta, TNF-alpha and IL-6 mRNA expression in macrophages in vitro as demonstrated by in situ hybridisation. Linomide administered daily subcutaneously from the day of inoculation completely prevented the development of clinical symptoms of EAN. Linomide administered from day 9 post immunisation (p.i.) significantly suppressed clinical EAN. Macrophages from Linomide-treated EAN rats showed decreased IL-1 beta, TNF-alpha and IL-6 mRNA expression in response to IFN-gamma and LPS. LPS-induced nitric oxide production by macrophages was also suppressed by Linomide in vitro. Linomide, however, does not affect macrophage death and release of lactate dehydrogenase. We conclude that Linomide may exert its actions in EAN and perhaps also in other autoimmune disease models, by suppressing macrophage functions.

Activation of alloreactive natural killer cells is resistant to cyclosporine

BACKGROUND

We have previously shown that cytotoxic T lymphocytes (CTL) with alloreactivity were induced when Wistar Furth (WF; RT1u) rats were immunized with allogeneic Brown Norway (BN; RT1n) cells. In contrast, when BN rats were immunized with WF cells, the allospecific response was confined to alloreactive natural killer (NK) cells, and no CTL activity was observed. In this study, the effect of cyclosporine (CsA) on the activation of alloreactive NK cells in vivo was analyzed.

METHODS

Distinct peritoneal effector cells from rats immunized with allogenic cells with or without concomitant CsA and/or interleukin (IL) 2 treatment were tested for specific cytolytic activity. Furthermore, the presumptive role of NK cells in rejection immunity was addressed in a cardiac graft model.

RESULTS

The results showed that doses of CsA that completely inhibited the activation of alloreactive CTL, only marginally affected the activation of alloreactive NK cells. We also showed that CsA treatment failed to prolong graft survival in BN recipients of WF hearts. Treatment of BN rats with CsA/IL-2 during immunization with allogeneic WF cells resulted in concomitant induction of alloreactive NK cells and alloreactive CTL.

CONCLUSIONS

We have demonstrated that CsA failed to suppress the activation of alloreactive NK cells. Consequently, the cardiac graft survival in the donor-recipient combination known to activate alloreactive NK cells was not significantly prolonged by CsA treatment, emphasizing the involvement of NK cells as effectors in organ rejection. Furthermore, the parallel emergence of alloreactive NK cells and CTL only in the presence of CsA/IL-2 indicated that CsA interfered with alloreactive NK cell-associated suppression of CTL activated by allogeneic tissue.

Prevention of superantigen-induced tolerance in vivo by interleukin-2 treatment

Injection of the superantigen staphylococcal enterotoxin A (SEA) activates both CD4+ and CD8+ T cells expressing certain families of T cell receptor (TCR) variable-region beta (V beta) chain. T cells respond with profound cytokine production and induction of cytotoxicity. Repeated injections, however, cause deletion and anergy of both CD4+ and CD8+ T cells, resulting in reduced frequency of SEA-responsive cells TCR-V beta11+ as well as reduced cytokine levels in serum upon challenge with SEA. Exogenous interleukin-2 (IL-2) in vivo rescued SEA-responsive CD4+ and CD8+ cells from SEA-induced deletion and/or increase expansion of SEA-primed cells as well as preventing downregulation of endogenous IL-2 production in vivo. Combined treatment with SEA and IL-2 also superinduced production of important cytokines for the cytotoxic function of T cells, tumour necrosis factor alpha, interferon gamma and IL-6, on a cellular level. These studies show that continuous stimulation with IL-2 in vivo could be useful for superantigen-based immunotherapy by induction of excessive T cell activation and by prevention of the development of T cell deletion and anergy.

Neuroradiographic findings in the newborn period and long-term outcome in children with symptomatic congenital cytomegalovirus infection

OBJECTIVE

To determine whether newborn cranial computed tomographic (CT) scan abnormalities predict an adverse neurodevelopmental outcome in children with symptomatic congenital cytomegalovirus (CMV) infection and to examine the association between clinical findings at birth and imaging abnormalities.

METHODS

The data from 56 children with symptomatic congenital CMV infection who underwent cranial CT scans as newborns and were enrolled in a long-term follow-up study were analyzed. The incidence of sequelae was compared between the groups of children with normal and abnormal imaging studies. The relationship between CT scan results and other newborn findings was also examined.

RESULTS

Abnormal CT scans were noted in 70% of subjects; intracerebral calcification was the most frequent finding. Most of the children with an abnormal newborn CT scan (90%) developed at least one sequela, compared with 29% of those with a normal study. Only 1 child with a normal CT scan had an IQ < 70, in contrast to 59% of those with imaging abnormalities. In addition, almost half of the children with CT abnormalities had an IQ < 50 compared with none of those with a normal CT scan. Newborn CT abnormalities were also associated with an abnormal hearing screen at birth and hearing loss on follow-up. None of the neonatal neurologic findings were predictive of an abnormal CT scan.

CONCLUSION

In neonates with symptomatic congenital CMV infection, a cranial CT scan is a good predictor of an adverse neurodevelopmental outcome. In addition, newborn clinical and laboratory findings did not predict neuroradiographic abnormalities in neonates with symptomatic congenital CMV infection.

Costimulation by B7-1 and LFA-3 targets distinct nuclear factors that bind to the interleukin-2 promoter: B7-1 negatively regulates LFA-3-induced NF-AT DNA binding

We have characterized the regulation of nuclear factors involved in transcriptional control of the interleukin-2 (IL-2) promoter-enhancer activity in Jurkat T cells stimulated with superantigen presented on HLA-DR transfectants combined with the ligands LFA-3 (CD58) and B7-1 (CD80). Gel shift analyses showed that NF-AT was strongly induced in LFA-3-costimulated Jurkat T cells, suggesting that NF-AT is a key target nuclear factor for the CD2-LFA-3 pathway. Studies using HLA-DR-B7-1-LFA-3 triple transfectants showed that the LFA-3-induced NF-AT DNA binding activity was negatively regulated by B7-1 costimulation. In contrast, induction of a CD28 response complex containing only c-Rel proteins was seen after B7-1 costimulation. Both LFA-3 costimulation and B7-1 costimulation induced the AP-1 and NF-kappaB nuclear factors. Distinct compositions of the NF-AT complexes were seen in B7-1- and LFA-3-costimulated cells. LFA-3 induced primarily Jun-D, Fra-1, and Fra-2, while B7-1 induced June-D-Fos complexes. In contrast, AP-1 and NF-kappaB complexes induced in B7-1- and LFA-3-costimulated T cells showed similar contents. Transient transfection of Jurkat T cells with a construct encoding the IL-2 enhancer-promoter region (position -500 to +60) linked to a luciferase reporter gene revealed that B7-1 costimulation was required to induce strong transcriptional activity. Combined B7-1-LFA-3 costimulation resulted in a synergistic increase in IL-2 transcriptional activity. Multimers of the AP-1, NF-AT, NF-kappaB, and CD28 response elements showed distinct kinetics and activity after LFA-3 and B7-1 costimulation and revealed that B7-1 and LFA-3 converge to superinduce transcriptional activity of the AP-1, NF-AT, and CD28 response elements. Transcriptional studies with an IL-2 enhancer-promoter carrying a mutation in the CD28 response element site revealed that the activity was reduced by 80% after B7-1 and B7-1-LFA-3 costimulation whereas the transcriptional activity induced by LFA-3 was unaffected. Our data strongly suggest a selectivity in induction of nuclear factors by the CD2-LFA-3 and CD28-B7-1 pathways. This selectivity may contribute to regulation of the levels of IL-2 induced by LFA-3 and B7-1 costimulation and favor autocrine and paracrine T-cell responses, respectively.

Linomide suppresses both Th1 and Th2 cytokines in experimental autoimmune myasthenia gravis

Suppressive effects of the synthetic immunomodulatory drug Linomide have been shown in several autoimmune models, including antibody-mediated experimental autoimmune myasthenia gravis (EAMG), a model for human myasthenia gravis (MG). To define the mechanisms underlying EAMG suppression, we injected Linomide subcutaneously at different doses into Lewis rats immunized with Torpedo acetylcholine receptor (AChR) in complete Freund's adjuvant (CFA), and investigated AChR-specific T and B cell responses, and the levels of lymph node cells expressing mRNA of different cytokines after AChR stimulation in vitro. Both 160 and 16, but not 1.6, mg/kg/day of Linomide effectively suppressed clinical muscle weakness, accompanied by decreased AChR-induced T and B cell responses. Linomide also suppressed the mRNA expression of the Th1 cytokines IFN-gamma, IL-12 and TNF-alpha as well as the Th2 cytokines IL-4 and IL-10, which are important in the immunopathogenesis of EAMG by promoting antibody production. There were no differences for IL-1beta, IL-6, lymphotoxin or TGF-beta expression in Linomide-treated vs nontreated control EAMG rats. We conclude that Linomide suppresses clinical EAMG as well as B and T cell responses to AChR by counteracting the production of AChR-induced Th1 and Th2 cytokines.

The tumour associated cell surface antigen A6H is costimulatory for human CD4+ but not CD8+ T cells

The A6H monoclonal antibody (mAb) recognizes a 120,000-140,000 MW antigen that is expressed at similar densities on 85-90% of human CD4+ and CD8+ T cells and on renal cell carcinomas. The binding of the A6H mAb induced a costimulatory signal in anti-CD3 activated T cells. In the present report, we show that A6H costimulated cell proliferation and cytokine production in purified CD4+ T cells. Unexpectedly, the CD8+ T-cell subpopulation failed to respond. CD4+ T cells costimulated with the A6H mAb upregulated CD80, CD86, CD71, interleukin-2 (IL-2)R alpha, IL-2R beta and IL-2R gamma, while no corresponding up-regulation of these cell surface molecules was seen in CD8+ T cells. In order to investigate the nature of the A6H mAb costimulus at the transcriptional level we have examined induction of the transcription factors OCT-1, AP-1 and NF-kappa B which are known to be transcriptional regulators of several cytokine and cytokine receptor genes, including the IL-2 and IL-2R genes. Co-ligation of the A6H antigen and the CD3 complex induced expression of the transcription factor AP-1 in CD4+ T cells, whereas no increase in NF-kappa B and octamer-binding (Oct) proteins was seen compared to T cells stimulated with anti-CD3 alone. Furthermore, no induction of AP-1 was seen in A6H costimulated CD8+ T cells. These results suggests that both proximal steps in CD8+ T-cell activation as well as the later phases are unresponsive to A6H ligation. Molecular differences of the A6H molecule or distinct regulation of the A6H transduced AP-1 activation pathway may exist in CD4+ and CD8+ T cell subpopulations.

Prevention of superantigen-induced down-regulation of T-cell mediated cytotoxic activity by IL-2 in vivo

Administration of staphylococcal enterotoxin A (SEA) to mice induces profound activation, cytokine production and cytotoxic activity of both CD4+ and CD8+ T cells, but subsequently activated cells are deleted or become anergic. This study demonstrates that administration of interleukin-2 (IL-2) can prevent sea-induced hyporesponsiveness in CD8+ cytotoxic T lymphocytes (CTL). Repeated injections with sea every fourth day resulted in severely reduced cytotoxic activity in the spleen, which correlated with a reduced number of sea-responsive T-cell receptor (TCR)-V beta 11+ CD8+ cells. Studies of purified TCR-V beta 11+ CD8+ cells showed that they possessed intact cytotoxic activity per cell compared with cells from mice given a single injection of SEA, indicating that deletion was the main mechanism for the reduced cytotoxic activity. Combined treatment with SEA and IL-2 increased the number of cytotoxic cells in the spleen after each SEA injection and prevented the down-regulation of cytotoxic activity. Increased cytotoxic activity could be related to increased number and proliferation of CD8+ IL-2R alpha + cells, suggesting that administration of IL-2 maintained IL-2 responsiveness among CD8+ cells. Studies of sorted TCR-V beta 11+ CD8+ cells demonstrated that combined treatment with SEA and IL-2 also increased cytotoxic activity per cell compared with treatment with SEA alone. Taken together, IL-2 administration in vivo augmented SEA-induced expansion of T cells as well as the cytotoxic activity per CTL, and prevented SEA-induced cell deletion.

The role of B7-1 and LFA-3 in costimulation of CD8+ T cells

This study compares the ability of LFA-3 (CD58) and B7-1 (CD80) ligands to provide costimulatory signals for superantigen (SAg)-stimulated CD8+ and CD4+ T cells. We show that B7-1 and LFA-3 costimulation activate CD8+ T cells to proliferation, cytokine production (IL-2, TNF, and IFN-gamma), and cytotoxicity. A long-lasting proliferative response was observed after combined DR/B7-1/LFA-3 costimulation. Detailed analysis of SEA-activated CD8+ T cells revealed that maximal production of IFN-gamma was seen in LFA-3-costimulated cells, while production of IL-2 was mainly induced after B7-1 costimulation. A fivefold increase in the IFN-gamma production was observed when activated CD8+ T cells were costimulated with Chinese hamster ovary (CHO)-DR/LFA-3 cells compared with the secretion induced by CHO-DR/B7-1. In contrast, SEA-treated CD4+ T cells costimulated with B7-1 or LFA-3 gave rise to a similar production of IFN-gamma, suggesting a preferential function for the CD2/LFA-3 pathway in the regulation of IFN-gamma in CD8+ T cells. Moreover, the generation of CTL was supported similarly by B7-1 and LFA-3 costimulation, but not by CHO-DR cells. We conclude that ligation of the CD28 and CD2 receptors mediate distinct effect on CD8+ and CD4+ T cell effector functions.

The role of B7-1 and LFA-3 in costimulation of CD8+ T cells

This study compares the ability of LFA-3 (CD58) and B7-1 (CD80) ligands to provide costimulatory signals for superantigen (SAg)-stimulated CD8+ and CD4+ T cells. We show that B7-1 and LFA-3 costimulation activate CD8+ T cells to proliferation, cytokine production (IL-2, TNF, and IFN-gamma), and cytotoxicity. A long-lasting proliferative response was observed after combined DR/B7-1/LFA-3 costimulation. Detailed analysis of SEA-activated CD8+ T cells revealed that maximal production of IFN-gamma was seen in LFA-3-costimulated cells, while production of IL-2 was mainly induced after B7-1 costimulation. A fivefold increase in the IFN-gamma production was observed when activated CD8+ T cells were costimulated with Chinese hamster ovary (CHO)-DR/LFA-3 cells compared with the secretion induced by CHO-DR/B7-1. In contrast, SEA-treated CD4+ T cells costimulated with B7-1 or LFA-3 gave rise to a similar production of IFN-gamma, suggesting a preferential function for the CD2/LFA-3 pathway in the regulation of IFN-gamma in CD8+ T cells. Moreover, the generation of CTL was supported similarly by B7-1 and LFA-3 costimulation, but not by CHO-DR cells. We conclude that ligation of the CD28 and CD2 receptors mediate distinct effect on CD8+ and CD4+ T cell effector functions.

Allogeneic heart transplantation activates alloreactive NK cells

The ability of natural killer (NK) cells to recognize and reject transplants has so far been shown in hematopoietic grafts only. This study was designed to ascertain whether NK cells may also be involved in the rejection of transplanted organs. In most rat strain combinations, immunization with allogeneic cells induces a T cell response with cytotoxic T lymphocyte (CTL) activation. We have previously found one exception to this. In contrast to Wistar Furth rats (WF, RT1u), which manifest allospecific CTL activation in response to immunization with Brown Norway (BN, RT1n) cells, BN rats immunized with repeated intraperitoneal (i.p.) injections of allogeneic WF spleen cells manifest activation of alloreactive NK effector cells. The alloreactive NK cells were of the TCR-, CD3-, CD8+, and NKR-P1 intermediate phenotype and killed target cells with alloselectivity. In this study we used a heart transplantation model to study the rejection response of BN rats receiving WF grafts. NK cell infiltration was greater in WF hearts transplanted to BN recipients than in BN hearts transplanted to WF recipients. Furthermore, the extent of T cell infiltration was less in BN recipients. In WF rats transplanted with allogeneic BN hearts, CTL were activated in response to i.p. challenge with allogeneic BN cells, whereas BN rats transplanted with allogeneic WF hearts and i.p. challenged with allogeneic WF cells, manifested activation of alloreactive NK cells but no measurable activation of classic CTL. The alloreactive NK cells killed their allogeneic targets with specificity and with potency comparable to that of CTL. Furthermore, WF grafts were rejected in BN recipients as efficiently as were BN grafts in WF recipients. These results not only show cardiac allografts to be able to activate alloreactive NK cells, but also suggest that NK cells may be involved in the rejection of solid organ transplants and function as classic CTL in certain donor-recipient combinations.

TCR alpha beta+ anti-tumor cytolytic T lymphocytes express NKR-P1 whilethe anti-tumor activity of TCR gamma delta+ T lymphocytes is not correlated to NKR-P1 expression

The CD8 alpha alpha homodimer as well as the NK cell receptor-protein 1 (NKR-P1) have been implicated to be preferentially expressed by T cells that develop extrathymically. We have earlier shown that intraperitoneal administration of radiated syngeneic W439 lymphoma cells in rat induces tumor-specific cytotoxic T cells (CTL) expressing the TCR alpha beta receptor as well as the TCR gamma delta receptor. In the present study we have addressed the expression of CD8 alpha alpha /alpha beta and NKR-P1 on these CTL and their correlation to cytotoxicity activity against the W439 tumor. The induced CD8+ T cells differentiated to effective cytotoxic cells regardless of the CD8 composition. NKR-P1+ T cells expressing CD8 were found in the peritoneal cavity of untreated rats and this cell population was markedly increased upon lymphoma immunization. Both TCR alpha beta+ cells and TCR gamma delta+ cells expressing NKR-P1 showed high cytotoxicity against the tumor. TCR gamma delta+ NKR-P1- cells were also cytotoxic against the tumor, while TCR alpha beta+ NKR-P1- cells showed no cytotoxicity. NKR-P1+ T cells (TCR alpha beta+ and TCR gamma delta+) were not cytotoxic against NK sensitive targets, which contradicts earlier data implicating a correlation between the expression of NKR-P1 and MHC-unrestricted cytotoxicity. In conclusion, TCR alpha beta+ anti-lymphoma CTL express high levels of LFA-1 and NKR-P1, while the TCR gamma delta+ CTL are not dependant on NKR-P1. These results suggest that NKR-P1 has a different function within the TCR alpha beta+ CTL than within the TCR gamma delta+ CTL in the recognition process of these lymphoma cells.