Roles of cytokines and T cells in the pathogenesis of myasthenia gravis.

Myasthenia gravis (MG) is characterized by muscle weakness and fatigue caused by the presence of autoantibodies against the acetylcholine receptor (AChR) or the muscle-specific tyrosine kinase (MuSK). Activated T, B and plasma cells, as well as cytokines, play important roles in the production of pathogenic autoantibodies and the induction of inflammation at the neuromuscular junction in MG. Many studies have focused on the role of cytokines and lymphocytes in anti-AChR antibody-positive MG. Chronic inflammation mediated by T helper type 17 (Th17) cells, the promotion of autoantibody production from B cells and plasma cells by follicular Th (Tfh) cells and the activation of the immune response by dysfunction of regulatory T (Treg ) cells may contribute to the exacerbation of the MG pathogenesis. In fact, an increased number of Th17 cells and Tfh cells and dysfunction of Treg cells have been reported in patients with anti-AChR antibody-positive MG; moreover, the number of these cells was correlated with clinical parameters in patients with MG. Regarding cytokines, interleukin (IL)-17; a Th17-related cytokine, IL-21 (a Tfh-related cytokine), the B-cell-activating factor (BAFF; a B cell-related cytokine) and a proliferation-inducing ligand (APRIL; a B cell-related cytokine) have been reported to be up-regulated and associated with clinical parameters of MG. This review focuses on the current understanding of the involvement of cytokines and lymphocytes in the immunological pathogenesis of MG, which may lead to the development of novel therapies for this disease in the near future.

Changes in serum complements and their regulators in generalized myasthenia gravis.

OBJECTIVE: To investigate changes in serum complements and their regulators in the pathogenesis of myasthenia gravis (MG). METHODS: Forty-four patients with acetylcholine receptor antibody-positive MG, as well as 20 patients with non-inflammatory neurological disorders were enrolled. Serum complements (C3, C4 and soluble C5b-9) and complement regulators (vitronectin, clusterin and properdin) were extensively analysed by enzyme-linked immunosorbent assay and their associations with clinical profiles of MG were examined. RESULTS: Serum C3, C4 and clusterin levels were not significantly different between patients with MG and controls. The patients with MG had higher soluble C5b-9 (P = 0.09) and vitronectin (P = 0.001) levels than the controls; moreover, vitronectin levels decreased after treatment (P = 0.09). Serum properdin (P = 0.03) levels were lower in the patients with MG than in the controls, and negatively correlated with the MG Activities of Daily Living score (rs = -0.26, P = 0.09) and with the presence of bulbar palsy (P = 0.04). CONCLUSION: Our results show that activation of complements and an altered complement network could contribute to the inflammatory pathogenesis of MG.

Peroxiredoxins are involved in the pathogenesis of multiple sclerosis and neuromyelitis optica spectrum disorder.

Peroxiredoxins (PRXs) are intracellular anti-oxidative enzymes but work as inflammatory amplifiers under the extracellular condition. To date, the function of PRXs in the pathogenesis of multiple sclerosis (MS) and neuromyelitis optica spectrum disorder (NMOSD) is not fully understood. The aim of this study was to investigate whether PRXs play a role in the pathogenesis of MS and NMOSD. We analyzed levels of PRXs (PRX1, PRX5 and PRX6) in the cerebrospinal fluid (CSF) and serum of 16 patients with MS, 16 patients with NMOSD and 15 patients with other neurological disorders (ONDs). We identified potential correlations between significantly elevated PRXs levels and the clinical variables in patients with MS and NMOSD. Additionally, pathological analyses of PRXs (PRX1-6) in the central nervous system (CNS) were performed using the experimental autoimmune encephalomyelitis (EAE), animal model of MS. We found that serum levels of PRX5 and PRX6 in patients with MS and NMOSD were higher compared with those in patients with ONDs (P < 0·05). Furthermore, high levels of PRX5 and PRX6 were partly associated with blood-brain barrier dysfunction and disease duration in NMOSD patients. No significant elevation was found in CSF PRXs levels of MS and NMOSD. Spinal cords from EAE mice showed remarkable PRX5 staining, especially in CD45+ infiltrating cells. In conclusion, PRX5 and PRX6 may play a role in the pathogeneses of MS and NMOSD.

Serum level of soluble urokinase plasminogen activator receptor (suPAR) as a disease severity marker of myasthenia gravis: a pilot study.

Myasthenia gravis (MG) is an autoantibody-mediated inflammatory disease of the neuromuscular junction. Biomarkers indicating disease activity in MG are warranted. Recently, the soluble urokinase plasminogen activator receptor (suPAR) has been reported to be associated with inflammation, tissue damage, disease activity and prognosis in various diseases, including autoimmune diseases. In this study, serum suPAR levels were measured in 40 patients with anti-acetylcholine receptor antibody-positive MG and 30 controls, and their correlations with clinical variables and severity scale scores were investigated. We identified that serum suPAR levels significantly correlated with MG activities of daily living scale (Spearman's ρ = 0·45; P = 0·004) and MG Foundation of America classification (Spearman's ρ = 0·37; P = 0·02) at serum sampling, but not with anti-acetylcholine receptor antibody titers. In conclusion, serum suPAR levels can be a candidate for a novel biomarker of disease activity in anti-acetylcholine receptor antibody-positive MG.

Comparison of brain atrophy in patients with multiple sclerosis treated with first- versus second-generation disease modifying therapy without clinical relapse.

BACKGROUND AND PURPOSE: The silent progression of patients with multiple sclerosis (MS) has been reported. The aim of this study was to investigate the association between brain atrophy rates and disease-modifying drugs (DMDs) in patients with MS during their relapse-free period. METHODS: Patients with relapsing-remitting MS were classified into two groups on the basis of clinical records, i.e. a first-generation DMD group treated with interferon-beta-1a, interferon-beta-1b or glatiramer acetate and a second-generation DMD group treated with dimethyl fumarate, fingolimod or natalizumab. Brain volume was calculated with SPM12. RESULTS: A total of 45 patients with relapsing-remitting MS were enrolled in the first-generation (n = 22) or second-generation (n = 23) DMD group. The annualized relapse rate was lower in the first-generation than in the second-generation DMD group (median 0.26 vs. 0.59; P < 0.001). The annualized atrophy rate of the normalized brain volume was not different between the first- and second-generation DMD groups after analysis of covariance (median 0.13% vs. 0.59%; P = 0.17). CONCLUSIONS: The median annualized atrophy rate of normalized brain volume in the first-generation DMD group was similar to the previously reported annual brain atrophy rate of healthy controls, which may suggest that treatment with a first-generation DMD need not be changed when patients with MS are clinically inactive.

Frequency and features of myasthenia gravis developing after thymectomy.

BACKGROUND AND PURPOSE: Thymectomy is an effective treatment for myasthenia gravis (MG) with anti-acetylcholine receptor (AChR) antibodies. We rarely encounter patients who develop MG after surgery for thymic tumors. This study aimed to investigate the characteristics and frequency of post-thymectomy onset (PostTx) MG. METHODS: We reviewed the clinical information of thymoma-associated MG in 158 patients. Of these, 18 (11%) patients with PostTx MG were identified. RESULTS: The presence of anti-AChR antibodies (82%) and electrophysiological abnormalities (50%) was confirmed before thymectomy in patients with PostTx MG. The clinical characteristics of PostTx MG were similar to those of pre-thymectomy onset (PreTx) MG. In PostTx MG, the duration between thymectomy and MG onset were distributed as < 6 months (early-onset PostTx MG) and ≥ 6 months (late-onset PostTx MG). Notably, some patients with late-onset PostTx MG were associated with thymoma relapse. CONCLUSION: Our results suggest that approximately 11% of patients with thymoma-associated MG were PostTx MG and pre-surgical assessment of anti-AChR antibody titer or electrophysiological testing may predict PostTx MG development. However, no difference in clinical manifestation and prognosis was observed between PreTx MG and PostTx MG.

Safety of tapering tacrolimus dose in patients with well-controlled anti-acetylcholine receptor antibody-positive myasthenia gravis.

BACKGROUND AND PURPOSE: Tapering immunosuppressants is desirable in patients with well-controlled myasthenia gravis (MG). However, the association between tapering of calcineurin inhibitor dosage and reduction-associated exacerbation is not known. The aim of this study was to clarify the frequency of reduction-associated exacerbation when tacrolimus is tapered in stable patients with anti-acetylcholine receptor antibody-positive MG, and to determine the factors that predict exacerbations. METHODS: We retrospectively analyzed 115 patients in whom tacrolimus dosage was tapered. The reduction-associated exacerbation was defined as the appearance or worsening of one or more MG symptoms <3 months after the reduction. RESULTS: Tacrolimus dosage was successfully tapered in 110 patients (96%) without any exacerbation. Five patients (4%) experienced an exacerbation, but symptoms were reversed in all patients when the tacrolimus dose was increased to the previous maintenance level. No patient developed an MG crisis. The age at onset was significantly earlier (30 vs. 56 years, P = 0.025) and the reduction in dosage was significantly larger (2.0 vs. 1.0 mg/day, P = 0.002) in patients with reduction-associated exacerbation than in those without exacerbation. The cut-off values determined in a receiver-operating characteristic curve analysis were 52 years (sensitivity, 57%; specificity, 100%) for the age at onset and 1.5 mg (sensitivity, 80%; specificity, 100%) for the dose reduction. CONCLUSION: Tapering of tacrolimus was possible in most patients with well-controlled anti-acetylcholine receptor antibody-positive MG. Early age at onset and a large reduction from maintenance dosage were associated with exacerbation. Reductions ≤1.5 mg/day from the maintenance dosage should be considered for patients with late-onset disease.

Recombinant thrombomodulin ameliorates experimental autoimmune encephalomyelitis by suppressing high mobility group box 1 and inflammatory cytokines.

Recombinant thrombomodulin (rTM) has pleiotrophic properties, including anti-coagulation and anti-inflammation; however, its effectiveness as a treatment for multiple sclerosis (MS) has not been evaluated fully. High mobility group box 1 (HMGB1) and proinflammatory cytokines, working as inflammatory mediators, are reportedly involved in the inflammatory pathogenesis of MS. The aim of this study was to determine whether rTM can be a potential therapeutic agent for experimental autoimmune encephalomyelitis (EAE). EAE mice received rTM treatment (1 mg or 0·1 mg/kg/day) from days 11 to 15 after immunization. The clinical variables, plasma levels of inflammatory cytokines and HMGB1 and pathological findings in EAE were evaluated. rTM administration ameliorated the clinical and pathological severity of EAE. An immunohistochemical study of the spinal cord showed weaker cytoplasmic HMGB1 staining in the rTM-treated EAE mice than in the untreated EAE mice. Plasma levels of inflammatory cytokines and HMGB1 were suppressed by rTM treatment. In conclusion, rTM down-regulated inflammatory mediators in the peripheral circulation and prevented HMGB1 release from nuclei in the central nervous system, suppressing EAE-related inflammation. rTM could have a novel therapeutic potential for patients with MS.

Adequate tacrolimus concentration for myasthenia gravis treatment.

BACKGROUND AND PURPOSE: A single, oral dose of 3 mg/day tacrolimus, approved for myasthenia gravis (MG) treatment in Japan, was shown to reduce steroid dose and anti-acetylcholine receptor (AChR) antibody titers as well as to improve MG symptoms. However, no studies have investigated the association between tacrolimus concentration and its clinical efficacy in MG. In this study, we aimed to determine the optimal tacrolimus concentration for MG treatment. METHODS: The trough tacrolimus concentration in 51 patients with MG (positive for anti-AChR antibody, n = 48; negative for anti-AChR and anti-muscle-specific tyrosine kinase antibodies, n = 3) who received 3 mg/day tacrolimus for more than 1 year was measured using a chemiluminescent enzyme immunoassay. The clinical characteristics of patients with MG as well as the dose of prednisolone used before and after tacrolimus treatment were evaluated retrospectively. RESULTS: The median trough tacrolimus concentration was 5.4 (range, 2.9-7.6) ng/mL, which was correlated with 'minimal manifestation or better status' (P = 0.0190, r = 0.3273) and the reduction in anti-AChR antibody 1 year after tacrolimus initiation (P = 0.0170, r = 0.3465). When the cut-off value for tacrolimus was defined as 4.8 ng/mL using a receiver operating characteristic curve, patients with adequate tacrolimus concentration (≥4.8 ng/mL) showed more reduction in anti-AChR antibody titers and more improvement in MG-related activities in daily life scores. More patients with adequate tacrolimus concentration achieved 'minimal manifestation or better status' compared with those with low tacrolimus concentration. CONCLUSIONS: An adequate tacrolimus concentration is required for better MG prognosis.

Serum antinuclear antibody may be associated with less severe disease activity in neuromyelitis optica.

BACKGROUND AND PURPOSE: Antinuclear antibody-positive multiple sclerosis (MS) patients have shorter disease duration and lower Expanded Disability Status Scale (EDSS) scores. The aim of this study was to compare clinical and laboratory features between MS and neuromyelitis optica (NMO) patients with and without autoantibodies and to investigate the prognosis of NMO in patients with and without autoantibodies. METHODS: The frequencies of antinuclear, anti-Sjögren's syndrome A (SSA)/Ro, anti-Sjögren's syndrome B (SSB)/La and anti-thyroid peroxidase (TPO) antibodies in the sera of 75 NMO patients and 131 MS patients were compared. Clinical and laboratory profiles were also compared between NMO patients with and without autoantibodies, including annual relapse rate and time from onset of NMO to EDSS scores of 4.0 (limited walking but without aid) and 6.0 (walking with unilateral aid). RESULTS: More NMO than MS patients had antinuclear and anti-SSA/Ro antibodies (31% vs. 10%, P < 0.001, and 21% vs. 3%, P < 0.001, respectively). Antinuclear antibody-positive NMO patients had a lower annual relapse rate from disease onset to serum sampling compared with antinuclear antibody-negative NMO patients, independent of treatment regimen. Antinuclear antibody-negative NMO patients reached an EDSS score of 6.0 earlier than antinuclear antibody-positive NMO patients (P = 0.026). Cerebrospinal fluid cell counts were higher in anti-SSA/Ro-positive than in anti-SSA/Ro-negative NMO patients. More anti-TPO antibody-positive than anti-TPO antibody-negative NMO patients had oligoclonal immunoglobulin G bands (60% vs. 11%, P = 0.048). CONCLUSIONS: Autoantibodies possibly modulate the pathophysiology of NMO. Antinuclear antibody may be associated with less severe disease activity or less disability in NMO.

Current symptomatology in multiple sclerosis and neuromyelitis optica.

BACKGROUND AND OBJECTIVES: Several symptoms and signs are characteristic of multiple sclerosis (MS) such as Lhermitte's sign, Uhthoff's phenomenon and painful tonic seizure. Neuromyelitis optica (NMO) is another inflammatory disease of the central nervous system, and most of the opticospinal form of MS is thought to be NMO. This study aimed to investigate the frequencies of symptoms and signs, previously regarded as characteristic of MS, in NMO and MS patients. METHODS: Consecutive Japanese NMO-plus patients [NMO (n = 30) or partial NMO (n = 18)] and MS patients (n = 128) seen at Chiba University Hospital between 2011 and 2012 were investigated for the frequencies of symptoms and signs characteristic of MS. Logistic regression analyses were used to identify factors that distinguished NMO-plus from MS. RESULTS: Univariate analyses revealed that tonic seizures, Lhermitte's sign, persistent pain, fatigue and girdle sensation were more frequent in NMO-plus patients than in MS patients. Multivariate logistic regression analysis showed that paroxysmal itching, Uhthoff's phenomenon, Lhermitte's sign and girdle sensation were more characteristic of NMO-plus than of MS. CONCLUSIONS: Several classical MS symptoms and signs are more frequent in NMO patients than MS patients, which may be caused by the differences in the severity of inflammation, and localization and extensiveness of demyelinated lesions.

Modulation of the kallikrein/kinin system by the angiotensin-converting enzyme inhibitor alleviates experimental autoimmune encephalomyelitis.

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS). Bradykinin is the end-product of the kallikrein/kinin system, which has been recognized as an endogenous target for combating CNS inflammation. Angiotensin-converting enzyme (ACE) inhibitors influence the kallikrein/kinin system and reportedly have immunomodulatory characteristics. The objectives of this study were to determine whether bradykinin is involved in the pathogenesis of experimental autoimmune encephalomyelitis (EAE), an animal model of MS, and whether bradykinin control by the ACE inhibitor could be a therapeutic target in MS. The ACE inhibitor enalapril (1·0 or 0·2 mg/kg/day) was administered orally to EAE mice and the serum levels of bradykinin and cytokines in EAE mice were analysed. As a result, the administration of enalapril increased serum bradykinin levels, decreased the clinical and pathological severity of EAE and attenuated interleukin-17-positive cell invasion into the CNS. Additionally, bradykinin receptor antagonist administration reduced the favourable effects of enalapril. Our results suggest that bradykinin is involved in the pathomechanism underlying CNS inflammation in EAE, possibly through inhibiting cell migration into CNS. Control of the kallikrein/kinin system using ACE inhibitors could be a potential therapeutic strategy in MS.

Serum cytokine and chemokine profiles in patients with myasthenia gravis.

Myasthenia gravis (MG) is an autoimmune-mediated inflammatory disease of the neuromuscular junction. Previous studies of animal MG models have suggested important roles of cytokines in MG pathogenesis, but adequate studies on cytokines in human MG are lacking. Using a multiplex suspension array system, we measured the serum levels of 27 cytokines/chemokines in 47 anti-acetylcholine receptor antibody-positive patients with MG and 20 normal controls (NC) to investigate the contribution of cytokines/chemokines toward MG pathogenesis. Correlations between clinical parameters and cytokine/chemokine levels in patients with MG were also examined. The serum levels of interleukin (IL)-15 (mean ± standard deviation: 6·85 ± 6·97 pg/ml) and vascular endothelial growth factor (VEGF) (96·21 ± 71·60 pg/ml) significantly increased, whereas IL-4 levels (3·57 ± 0·86 pg/ml) decreased in patients with MG compared with NC (IL-15: 4·42 ± 1·55 pg/ml; VEGF: 63·51 ± 32·95 pg/ml; IL-4: 4·15 ± 0·81 pg/ml, P < 0·05). In addition, eight cytokines (IL-4, IL-8, IL-15, eotaxin, macrophage inflammatory protein-1α, macrophage inflammatory protein-1ß, VEGF and IL-1b) were significantly changed among MG patients with thymoma, MG patients without thymoma and NC (P < 0·05). Some cytokines, such as IL-4, IL-15, and VEGF, may play roles in the pathogenesis of MG.

Anti-high mobility group box 1 monoclonal antibody ameliorates experimental autoimmune encephalomyelitis.

High mobility group box 1 (HMGB1) is an established inflammatory mediator when released from cells. Recent studies have implicated extracellular HMGB1 in the pathogenesis of various autoimmune diseases. The objective of this study was to determine whether HMGB1 could be a therapeutic target for experimental autoimmune encephalomyelitis (EAE). In this study, an anti-HMGB1 monoclonal antibody was injected intraperitoneally into a mouse model of EAE. We also measured serum cytokines levels in EAE and anti-HMGB1 monoclonal antibody-treated EAE. As a result, intraperitoneal injection of an anti-HMGB1 monoclonal antibody ameliorated the clinical and pathological severity of EAE and attenuated interleukin-17 up-regulation in serum. In conclusion, HMGB1 is involved in EAE pathogenesis and could trigger inflammation in the central nervous system. The novel aspect of this study is the demonstration that anti-HMGB1 ameliorates EAE. HMGB1 may be a novel therapeutic strategy for multiple sclerosis.

Different responses to interferon beta-1b treatment in patients with neuromyelitis optica and multiple sclerosis.

BACKGROUND: Although the benefit of treatment for relapsing-remitting multiple sclerosis (MS) is firmly established, whether interferon beta-1b (IFNB-1b) therapy is efficacious for neuromyelitis optica (NMO) has been debated. METHODS: We reviewed the responses to IFNB-1b treatment in 18 patients with relapsing NMO and compared the results with those from 38 patients with relapsing-remitting MS. We compared clinical characteristics, the annualized relapse rate (ARR) and the probability of being relapse free before and after IFNB-1b treatment in patients with NMO and MS. RESULTS: The proportion of patients with more than 50% increase in the ARR after IFNB-1b treatment was much higher in NMO than in MS (P = 0.046). ARR was significantly lower in patients with MS after IFNB-1b administration than before (P = 0.015), but not in NMO. Kaplan-Meier and log-rank statistical analyses revealed that relapse-free rates were lower in NMO than MS after IFNB-1b treatment (P = 0.032). The analyses also showed lower relapse-free rates during the pre-IFNB-1b treatment period than the post-IFNB-1b treatment period in MS (P < 0.001), but not in NMO. CONCLUSION: IFNB-1b treatment does not appear to be effective for preventing relapse in NMO likely because of differences between the immune-pathogenesis of NMO and MS.

Effects of glycine betaine on bone marrow death and intestinal damage by gamma rays and carbon ions.

In this study, we investigated the effects of glycine betaine (GB) on bone marrow death and intestinal damage by gamma rays or carbon ions. C(3)H/He female mice received an i.p.-injection of GB before or after whole-body irradiation with gamma rays or 50 keV microm(-1) carbon ions. The irradiated mice were observed to determine the mortality for 30 days after exposure. Mice were also killed at 3.5 days after the exposure to determine the intestinal damage. The numbers of crypts per transverse circumference were counted using a microscope. For the bone marrow death, GB (93 mg GB per mouse) significantly (p < 0.05) increased the percentage survival for both radiations. For the intestinal damage, GB (93 mg GB per mouse) significantly (p < 0.05) increased the crypt survival for gamma rays, but not for carbon ions. GB might be a potential protector against normal tissue damage as a side effect in radiotherapy.

In vivo radiobiological assessment of the new clinical carbon ion beams at CNAO.

In this article, the in vivo study performed to evaluate the uniformity of biological doses within an hypothetical target volume and calculate the values of relative biological effectiveness (RBE) at different depths in the spread-out Bragg peak (SOBP) of the new CNAO (National Centre for Oncological Hadrontherapy) carbon beams is presented, in the framework of a typical radiobiological beam calibration procedure. The RBE values (relative to (60)Co γ rays) of the CNAO active scanning carbon ion beams were determined using jejunal crypt regeneration in mice as biological system at the entrance, centre and distal end of a 6-cm SOBP. The RBE values calculated from the iso-effective doses to reduce crypt survival per circumference to 10, ranged from 1.52 at the middle of the SOBP to 1.75 at the distal position and are in agreement with those previously reported from other carbon ion facilities. In conclusion, this first set of in vivo experiments shows that the CNAO carbon beam is radiobiologically comparable with the NIRS (National Institute of Radiological Sciences, Chiba, Japan) and GSI (Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany) ones.

In vivo induction of cytotoxic T lymphocytes specific for a single epitope introduced into an unrelated molecule.

Cytotoxic T lymphocytes (CTLs) recognise antigenic peptides in the context of major histocompatibility complex (MHC) class I molecules on virus-infected cells. The formation and transportation of antigenic peptides to class I MHC in the cells are multi-step reactions known as antigen processing. In order to design a good DNA vaccine, it is important to dissect the specificity of antigen processing. Here we describe the construction of an epitope-based plasmid vector as a device to investigate antigen processing in transfected cells. The epitope-based plasmid vector was constructed by insertion of an epitope-encoding minigene into the lacZ gene. We used a CTL epitope on influenza A virus nucleoprotein (NP366-374 epitope) as a model. Upon transfection, the epitope-based plasmid vector induced the expression of NP epitope antigenically as well as immunogenically. Immunization of mice with plasmid-transfected cells was able to induce NP epitope-specific CTLs in vivo. Moreover, the plasmid vector functioned as a gene vaccine; NP epitope-specific CTLs were primed in vivo upon transfection of the vector into dermis by electroporation. The results suggest that this epitope-based DNA delivery system may provide a new strategy for in vivo induction of epitope-specific CTLs to investigate antigen processing and presentation.

Radiosensitivity of CD45RO+ memory and CD45RO- naive T cells in culture.

Radiosensitivities of various human T-cell subsets were investigated by a proliferation assay and by a single-cell gel electrophoresis assay. Each T-cell subset was purified using a cell sorter and was induced to proliferate by ionomycin and interleukin 2. Unsorted T cells showed biphasic dose-survival curves, indicating the heterogeneity of T cells in terms of radiosensitivity. Purified CD4+ helper and CD8+ killer T cells showed similar biphasic dose-survival curves. Hence both T-cell subsets were composed of cells of different radiosensitivity. The T-cell subsets belonging to different activation stages such as CD45RO+ memory and CD45RO- naive T cells had different dose-survival curves. The former was more radiosensitive than the latter. The high radiosensitivity of CD45RO+ cells was also demonstrated by single-cell gel electrophoresis after irradiation. This is the first demonstration that a particular cell surface marker on T cells is correlated with greater radiosensitivity.

OK-432 reduces mortality and bacterial translocation in irradiated and granulocyte-colony stimulating factor (G-CSF)-treated mice.

Bacterial translocation/Acute radiation syndrome/Endotoxin/G-CSF/OK-432 Acute radiation induces bacterial translocation from the gut, followed by systemic infection and sepsis. In order to reduce the mortality after acute whole body irradiation, it is essential to control bacterial translocation. In this study, we established a bacterial translocation assay as a sensitive method to detect minor mucosal injury by radiation. By utilizing this assay, we evaluated the adverse effects, if any, of hematopoietic reagents on the mucosal integrity in the respiratory and gastro-intestinal tracts. Bacterial translocation to the liver and spleen occurred after whole-body irradiation if the dose exceeded 6 Gy. The administration of G-CSF unexpectedly increased the bacterial translocation in 8 Gy-irradiated mice. The pharmaceutical preparation of low-virulent Streptococcus pyogenes, OK-432, significantly reduced the endotoxin levels in peripheral blood without any reduction of bacterial translocation. A combined treatment with G-CSF and OK-432 decreased bacterial translocation and prevented death. This result indicates that the early administration of G-CSF has an adverse effect on bacterial translocation, and that a combined treatment of G-CSF and OK-432 attenuates the adverse effect of G-CSF and improves the survival rate after acute irradiation.