Medial and lateral laxity in knees with advanced medial osteoarthritis.

OBJECTIVE: An increase in coronal laxity is recognized as a risk factor for progression of knee osteoarthritis (OA). The purpose of this study was to evaluate coronal laxity, which was defined as the angular motion from the neutral, unloaded (baseline) position to the loaded position, in patients with advanced medial knee OA. METHOD: Preoperative coronal laxity was assessed using radiographs in patients with medial knee OA undergoing total knee arthroplasty by applying a force of 150 N with an arthrometer. A consecutive series of 211 knees with OA and 40 normal control knees were examined. A knee with OA was defined as clinically "balanced" when the difference between medial and lateral laxity was 3° or less. Values are expressed as median [25th, 75th percentile]. RESULTS: The laxity was 4° [3, 5] from the baseline on the medial side and 3° [2, 4] on the lateral side. The distribution of medial and lateral laxity indicated that 90% (189/211) of patients fell within 3°. The equivalence test showed that the medial and lateral laxity was similar, with an equivalence margin of 3° (P < 0.001). In the control knees, the laxity was 3° [2, 4] from the baseline on the medial side and 2° [2, 4] on the lateral side. The differences between the knees with advanced OA and the controls were significant (P = 0.005, medial; P = 0.006, lateral). CONCLUSION: This study showed that a clinically balanced knee was maintained even in patients with advanced medial knee OA.

Effect of voluntary soft tissue tension and articular conformity after total knee arthroplasty on in vivo anteroposterior displacement.

The in vivo relationship between the degree of voluntary soft tissue tension and articular conformity after total knee arthroplasty (TKA) and anteroposterior (AP) displacement was simultaneously investigated by analyzing LCS prostheses (posterior cruciate ligament-sacrificing rotating platform design) in 20 knees from 20 patients. AP displacement was measured using the KT-2000 arthrometer, at 30° and 75° flexion, while patients were conscious and under anesthesia; 30° flexion was regarded as high conformity and 75° as low conformity. Mean displacements at 30° and 75° were 5.1mm and 7.0mm, respectively, in conscious patients, and 6.7 mm and 7.7 mm, respectively, in patients under anesthesia. AP displacement was significantly associated with soft tissue tension (p=0.026) and conformity (p=0.001). No interaction was observed between the two variables (p=0.193). Surgeons should recognize that AP displacement is greater in anesthetized patients than in conscious patients, regardless of the degree of conformity, and that higher conformity shows less displacement, regardless of the degree of soft tissue tension. These results may help surgeons to determine the intra-operative AP displacement required for proper postoperative displacement in the current prosthetic design.

Protective mechanism of ultrafiltration against cardiopulmonary bypass-induced lung injury.

BACKGROUND: We previously demonstrated a negative effect of cardiopulmonary bypass (CPB) in a canine model of single-lung graft function and an improved effect with ultrafiltration during CPB. OBJECTIVE: To investigate the mechanism of these effects, focusing on cytokines and pulmonary surfactants using real-time quantitative reverse transcriptase-polymerase chain reaction (RT-PCR). MATERIALS AND METHODS: Fifteen left-sided single-lung transplant procedures were performed in pairs of dogs. The animals were divided into 3 groups. In one group, transplantation was performed without CPB (non-CPB group); in a second group, transplantation was performed with CPB and CPB flow was decreased slowly and pulmonary artery pressure was controlled (CPB group; and in the third group, transplantation was performed with CPB and ultrafiltration (CPB+UF group). Grafted lung specimens were harvested for RT-PCR of cytokines (IL-6, IL-8, and IL-10) and surfactant proteins (SP-A, SP-B, and SP-C). RESULTS: Real-time quantitative RT-PCR demonstrated increased IL-6 expression in the CPB group compared with the non-CPB group. IL-6 gene expression was suppressed and pulmonary surfactant restored using ultrafiltration. Gene expression of surfactant protein (SP)-A, SP-B, and SP-C was decreased in the CPB group compared with normal lung and ultrafiltration groups, which demonstrated sustained gene expression of SP-A and SP-B. CONCLUSION: Cardiopulmonary bypass has negative effects on grafts; however, ultrafiltration attenuates acute lung dysfunction by decreasing the inflammatory response and increasing pulmonary surfactant.

Prediction of disease-associated single nucleotide polymorphisms using virtual genomes constructed from a public haplotype database.

OBJECTIVES: Simultaneous dealing of hundreds of thousands of single nucleotide polymorphisms (SNPs) in genome-wide association studies is laborious. The aim of our study is to develop a method to decrease the number of candidate SNPs prior to the genotyping of study subjects. METHODS: We created virtual genotype data on case and control subjects from data of the International HapMap Project by using haplotype-based simulation method. We repeated virtual case-control association studies and selected candidate SNPs. We applied the selected SNPs to previously published genetic case-control studies. Sensitivity to detect association with causative genes using our method was compared to the original studies and results using tag SNPs. RESULTS: We found a discrete distribution pattern of SNPs, which was able to produce significant results in case-control association studies. The number of candidate SNPs that we selected was 24.7% of the number of the original set of SNPs. We applied this method to previously published genetic case-control studies and found that the use of candidate SNPs improved the sensitivity for detecting significant alleles, both compared to the original studies and to the use of tag SNPs. The results were not affected by the difference of the diseases and genes involved. CONCLUSIONS: Our simulation-based approach has advantages of reducing costs and improving performance to detect significant alleles. This method can be used without considering the specific disease and genes involved.

Economic impact of extended treatment with peginterferon alpha-2a and ribavirin for slow hepatitis C virologic responders.

It is difficult to achieve a sustained virologic response from antiviral therapy for genotype 1 hepatitis C virus-infected patients without a sufficient virologic response in the early weeks after treatment. However, a recent study has reported on the effectiveness of an extended course of treatment with peginterferon alpha-2a plus ribavirin for slow virologic responders. The aim of this study was to evaluate the economic impact of an extended course of treatment. A Markov cohort model of hepatitis C was designed in order to demonstrate the clinical states, based on the assigned transition probabilities over 30 years. The slow virologic responders treated with an extended 72-week course of therapy could increase by 0.55 the quality-adjusted life years (=15.35-14.80) and reduce the lifetime cost by $2762 (=71 559-69 438) in comparison with those treated by the standard 48-week course. One-way sensitivity analyses did not change the cost-effectiveness. Therefore, the extended 72 weeks of treatment with peginterferon alpha-2a plus ribavirin for slow virologic responders could be cost-effective in comparison with the standard 48 weeks of treatment.

Accuracy in the diagnostic prediction of acute appendicitis based on the Bayesian network model.

OBJECTIVES: The diagnosis of acute appendicitis is difficult, and a diagnostic error will often lead to either a perforation or the removal of a normal appendix. In this study, we constructed a Bayesian network model for the diagnosis of acute appendicitis and compared the diagnostic accuracy with other diagnostic models, such as the naive Bayes model, an artificial neural network model, and a logistic regression model. METHODS: The data from 169 patients, who suffered from acute abdominal pain and who were suspected of having an acute appendicitis, were analyzed in this study. Nine variables were used for the evaluation of the accuracy of the four models for the diagnosis of an acute appendicitis. The naive Bayes model, the Bayesian network model, an artificial neural network model, and a logistic regression model were used in this study for the diagnosis of acute appendicitis. These four models were validated by using the ".632+ bootstrap method" for resampling. The levels of accuracy of the four models for diagnosis were compared by the error rates and by the areas under the receiver operating characteristic curves. RESULTS: Through the course of illness, 50.9% (86 of 169) of the patients were diagnosed as having an acute appendicitis. The error rate was the lowest in the Bayesian network model, as compared with the other diagnostic models. The area under the receiver operating characteristic curve analysis also showed that the Bayesian network model provided the most reliable results. CONCLUSION: The Bayesian network model provided the most accurate results in comparison to other models for the diagnosis of acute appendicitis.

A modified method of activity-based costing for objectively reducing cost drivers in hospitals.

OBJECTIVES: Activity-based costing (ABC) is widely used to precisely allocate indirect costs to medical services. In the ABC method, the indirect cost is divided among the medical services in proportion to the volume of "cost drivers", for example, labor hours and the number of hours of surgery. However, the workload of data collection of cost drivers can be time-consuming and a considerable burden if there are many cost drivers. The authors aim to develop a method for objectively reducing the cost drivers used in the ABC method. METHODS: In the ABC method, the cost driver is assigned for each activity. We assume that these activities and cost drivers are the best combination. Our method, that is cost driver reduction (CDR), can objectively select surrogates of the cost drivers for each activity in ABC from candidate cost drivers. Concretely, the total indirect cost of an activity is temporarily allocated to the medical services using each candidate of cost drivers. The difference between the costs calculated by each candidate and the proper cost driver used in ABC is calculated to evaluate the similarity by the evaluation function. RESULTS: We estimated the cost of laboratory tests using our method and revealed that the number of cost drivers could be reduced from seven in the ABC to four. Similarly, the results of cost estimation obtained by our method were as accurate as those calculated using the ABC. CONCLUSIONS: Our method provides two advantages compared to the ABC method: 1) it provides results that are as accurate as those of the ABC method, and 2) it is simpler to perform complicated estimation of hospital costs.

Expression of immunoglobulin E-dependent histamine-releasing factor in idiopathic nephrotic syndrome of childhood.

Concanavarin-A (conA)-stimulated peripheral blood mononuclear cells (PBMNC) from patients with idiopathic nephrotic syndrome (INS) produce putative factors that increase vascular permeability. These factors are expressed in the nephrotic phase but are reduced in the convalescent phase. To identify the genes that are expressed only in the nephrotic phase, we performed cDNA subtraction using conA-stimulated PBMNC from three patients with INS. We isolated several gene transcripts in all three subtracted cDNA libraries. Among these genes, IgE-dependent histamine-releasing factor (HRF) was overexpressed in the nephrotic phase not only at the mRNA level but also at the protein level in another 10 patients with INS. Moreover, we found increased secretion of HRF from conA-stimulated PBMNC in the nephrotic phase. The results suggest that HRF is involved in the pathogenesis of idiopathic nephrotic syndrome.

Biclonal expansion of T cells infected with monoclonal Epstein-Barr virus (EBV) in a patient with chronic, active EBV infection.

Recent studies have suggested that a high percentage of Epstein-Barr virus (EBV)-infected lymphocytes in peripheral blood of patients with chronic, active EBV infection (CAEBV) is of T cell origin. Although T cells are expanded oligoclonally in CAEBV, it is not clear whether the restricted diversity of T cells arise from immune reaction against EBV-related antigens or from proliferation of EBV-infected cells. We experienced a patient with CAEBV who had biclonal expansion of peripheral blood T cells. We identified clonotypes of these two T cell clones in detail and purified the T cell clones. EBV infected mainly the two T cell clones, whereas the viral loads in peripheral blood cells other than these T cell clones were low or undetectable. The EBV strains infecting the two T cells clones were indistinguishable from each other by a series of genotype analyses of the virus. These results suggest that the two T cell clones infected with the same monoclonal EBV proliferated in peripheral blood of the patient.

Large vessel arteritis associated with human herpesvirus 6 infections.

A 9-month-old boy presented with chronic arteritis of the aorta and its major branches. The clinical manifestations at onset of his illness were compatible with those of Kawasaki syndrome. However, the febrile period lasted for 2 months despite various immunosuppressive therapies, and the levels of C-reactive protein remain high 18 months after onset. Elevated circulating immune complexes, decreased serum complement levels, hypergammaglobulinaemia and monoclonal gammopathy were observed. Active HHV-6 infection was shown by increased serum levels of antihuman herpesvirus-6 (HHV-6) IgG and IgM antibodies, and positive HHV-6 DNA in sera, peripheral blood mononuclear cells (PBMNC) and lymph nodes. HHV-6 was actively replicating in PBMNC and lymph nodes, as shown by the detection of transcripts for the virus structural antigen. These results suggest that large vessel arteritis can be associated with HHV-6 infection.

Specific immunoglobulin E responses in ZAP-70-deficient patients are mediated by Syk-dependent T-cell receptor signalling.

ZAP-70 deficiency is a rare primary immunodeficiency characterized by the absence of peripheral CD8+ T cells and defects in T-cell receptor (TCR) signalling. T cells in ZAP-70-deficient patients are assumed to have no helper functions for B-cell immunoglobulin synthesis, whereas the patients rarely have antigen-specific antibodies. We experienced a ZAP-70-deficient patient, who had immunoglobulin E (IgE) antibodies specific to food allergens, and we investigated the mechanisms of switching to IgE in the patient. Peripheral blood mononuclear cells from the patient did not proliferate upon stimulation with the antigens but produced distinct levels of interleukin-4 (IL-4). Cell sorting analysis indicated that the cells that produced IL-4 in response to the antigens were enriched in CD4+ T cells. Purified CD4+ T cells from the patient produced IL-4 and expressed CD40L upon stimulation with anti-CD3. Moreover, CD4+ T cells pretreated with anti-CD3 induced mature epsilon transcript on naive B cells. Since the results indicated that there remained sufficient T-cell receptor (TCR)-signalling in the patient's T cells to exert antigen-specific IgE switching on B cells, we next investigated the expression of the ZAP-70-homologous kinase Syk. Syk was present in high levels in patient's CD4+ T cells and was tyrosine-phosphorylated after TCR stimulation. Inhibition of Syk by piceatannol resulted in decreased production of IL-4 and expression of CD40L on patient's CD4+ T cells. Moreover, Syk was expressed on all human T-cell leukaemia virus (HTLV-1)-transformed T-cell lines derived from peripheral blood of the patient, whereas it was low or undetectable in control lines. It was therefore concluded that specific IgE responses in the patient were most likely to be mediated by Syk-dependent TCR-signalling.

Oligoclonally expanding gammadelta T lymphocytes induce IgA switching in IgA nephropathy.

The aetiology of IgA nephropathy (IgAN) is closely related with abnormality of mucosal immunity. We investigated the roles of gammadelta T cells in the regulation of IgA production by B cells in IgAN patients. The proportion of gammadelta T cells in peripheral blood mononuclear cells (PBMNC) was higher in IgAN patients than in the controls and was found to be correlated with the proportion of surface IgA-positive (sIgA+) B cells, which are precursors of IgA-secreting plasma cells. After in vitro PWM stimulation, sIgA expression on B cells and IgA production were significantly enhanced in PBMNC obtained from IgAN patients, whereas the enhancements were abolished by removal of gammadelta T cells from the PBMNC. Purified gammadelta T cells from IgAN patients induced surface IgA expression on naïve sIgD+ B cells more effectively than did alphabeta T cells. Moreover, stimulated gammadelta T cells from IgAN patients produced a larger amount of TGF-beta1, which is one of the main cytokines that induces IgA class switching on B cells, as compared with alphabeta T cells and control gammadelta T cells. The expanded gammadelta T cells from IgAN patients exclusively expressed Vgamma9, and the nucleotide sequences of junctional regions of Vgamma9 showed very limited TCR diversities. It was therefore concluded that gammadelta T cells, which are expanded in response to specific antigens, enhance IgA class switching on B cells in IgAN patients.

Suppressive effect of antiulcer agents on granulocytes--a role for granulocytes in gastric ulcer formation.

Many clinicians have believed that H2-blockers and proton pump inhibitors ameliorate gastric ulcers via their antacid function. We examined the effects of these antacids on granulocytes. Gastric ulcer patients were administered an H2-blocker or proton pump inhibitor for a week and the number of granulocytes and the superoxide production were examined. To determine the trafficking of granulocytes, mice were exposed to restraint stress for 24 hr. The H2-blocker decreased the number of granulocytes, while the proton pump inhibitor suppressed their superoxide production in humans and mice. The major function of H2-blockers and proton pump inhibitors in curing gastric ulcers seems to be their suppressive effects on granulocytes. In this case, stress accelerates the trafficking of granulocytes from the bone marrow to the gastric mucosa. If we demonstrate a role for granulocytes in gastric ulcer formation, an gap in the acid-pepsin theory and the Helicobacter pylori theory is filled in.

An anti-CD5 monoclonal antibody ameliorates proteinuria and glomerular lesions in rat mesangioproliferative glomerulonephritis.

BACKGROUND: Increased numbers of lymphocytes have been identified in biopsy specimens of human mesangial proliferative glomerulonephritis (GN). However, the causal relationship between infiltrating T lymphocytes and mesangial changes in mesangial proliferative GN has not been previously evaluated. In this study, we elucidated the role of lymphocytes in the development of mesangial proliferative GN. METHOD: Immunohistological and flow cytometric analyses as well as a reverse transcription-polymerase chain reaction (RT-PCR) studies were performed in monoclonal antibody (mAb) 1-22-3-induced Thy 1.1 GN. To elucidate the role of these lymphocytes, depletion studies were carried out using anti-CD8 mAb (OX-8), which depletes both CD8+ T lymphocytes and natural killer (NK) cells and anti-CD5 mAb (OX-19), which depletes both CD4+ and CD8+ T lymphocytes. RESULTS: Immunofluorescence (IF) studies revealed that NK cells and CD4+ T lymphocytes were recruited into glomeruli. Glomerular mRNA expression for interferon-gamma, interleukin-2 (IL-2), IL-10, and perforin increased after induction of GN. Increased expressions of several chemokines, which have the potential to attract lymphocytes, were also detected. Anti-CD8 mAb treatment completely prevented the recruitment of NK cells; however, it had no protective effect on proteinuria and mesangial injury. By contrast, anti-CD5 mAb treatment suppressed the recruitment of CD4+ T lymphocytes into glomeruli and reduced proteinuria (60.4 +/- 25.7 vs. 120.0 +/- 32.3 mg/day, P < 0.05) and mesangial changes evaluated by total number of cells in glomeruli (63.2 +/- 6.0 vs. 81.4 +/- 5.9, P < 0.01) and alpha-smooth muscle actin staining score (1.4 +/- 0.2 vs. 2.2 +/- 0. 4, cf2eth P < 0.01) on day 14 after induction of GN. mRNA expression for IL-2 was significantly reduced by OX-19 treatment. CONCLUSION: T lymphocytes participate in the development of mesangial proliferative GN.

Inhibition of concanavalin A-induced hepatic injury of mice by bacterial lipopolysaccharide via the induction of IL-6 and the subsequent reduction of IL-4: the cytokine milieu of concanavalin A hepatitis.

BACKGROUND/AIMS: Liver natural killer 1.1 antigen (NK1)+ T cells and IL-4 play a crucial role in concanavalin-A (Con-A)-induced hepatic injury in mice, and a T helper (Th) 2 immune response was thus suggested to be involved. This study was designed to examine the effect of bacterial lipopolysaccharide (LPS), a strong inducer of a Th 1 immune response, on Con-A hepatic injury and also to clarify further the cytokine milieu of Con-A hepatitis. METHODS: LPS were injected into mice before Con-A injection to evaluate the effect on hepatic injury. The effect of the pretreatment with various T1 and Th2 cytokines or anti-cytokine antibodies on Con-A hepatitis was also examined. RESULTS: LPS in quantities > or = 500 ng/mouse, when injected 24 h before Con-A injection, abrogated the Con-A-induced elevation of transaminases, hepatocyte destruction and serum IL-4 elevation. This LPS inhibitory effect was blocked when the mice were injected with either anti-IL-6 antibody before LPS injection or IL-4 before Con-A injection. IL-6, but neither IL-10 nor IL-12 pretreatment suppressed Con-A-induced IL-4 production and hepatitis. NK1+ T cells produced IL-4 while both NK1+ T cells and NK1- T cells produced IFN-gamma. Not only anti-IL-4 antibody but also the anti-IFN-gamma antibody pretreatment inhibited Con-A hepatitis. However, although the anti-IL4 antibody suppressed IL-4 alone, the anti-IFN-gamma Ab unexpectedly inhibited both IFN-gamma and IL-4 elevation, while IL-4 injection evoked a moderate Con-A hepatitis even in the anti-IFN-gamma antibody-treated mice. Furthermore, the IL-4 mutant mice did not develop Con-A hepatitis. CONCLUSION: LPS inhibited Con-A hepatitis by inducing IL-6 and thereby inhibited IL-4 synthesis from NK1+ T cells. Although both IL-4 and IFN-gamma were required for the full induction of Con-A hepatic injury, exogenous IL-4 evoked a moderate Con-A hepatitis, even in the absence of IFN-gamma.

Circadian rhythm of leucocytes and lymphocytes subsets and its possible correlation with the function of the autonomic nervous system.

There are physiological variations in the levels of leucocytes. Among these, the circadian rhythm is very important in terms of the magnitude. Since newly identified lymphocyte subsets (i.e. extrathymic T cells) have recently been detected, a comprehensive study of the circadian rhythm was conducted. All leucocytes were found to vary in number or proportion with a circadian rhythm and were classified into two groups. One group--granulocytes, macrophages, natural killer (NK) cells, extrathymic T cells, gammadelta T cells, and CD8+ subset--showed an increase in the daytime (i.e. daytime rhythm). The other group--T cells, B cells, alphabeta T cells, and CD4+ subset--showed an increase at night. Humans are active and show sympathetic nerve dominance in the daytime. Interestingly, granulocytes and lymphocyte subsets with the daytime rhythm were found to carry a high density of adrenergic receptors. On the other hand, lymphocyte subsets with the night rhythm carried a high proportion of cholinergic receptors. Reflecting this situation, exercise prominently increased the number of cells with the daytime rhythm. These results suggest that the levels of leucocytes may be under the regulation of the autonomic nervous system.

Neonatal granulocytosis is a postpartum event which is seen in the liver as well as in the blood.

In a recent series of studies, we demonstrated that stress in humans and animals, with resultant sympathetic nerve strain, induces severe granulocytosis, because granulocytes carry adrenergic receptors on the surface. Because activated granulocytes produce free radicals and superoxides, they sometimes induce tissue damage if the stress is too strong or continuous. Human neonates are also known to show high levels of granulocytes in the peripheral blood. In this study, we investigated whether such neonatal granulocytosis are a stress-associated response at birth. Both human and mouse materials, before and after birth, were used. The number of leukocytes in the blood, as well as some other factors in the serum, were measured. Although levels of granulocytes were found to be low in fetal humans and mice, they increased sharply after birth. In parallel with this postpartal granulocytosis, transaminases in sera increased transiently. In reference to results of a transient elevation in the levels of catecholamines at birth in mice, all these phenomena resemble stress-associated responses. Indeed, fatty liver and hematopoietic destruction in the liver were also observed in mice and humans. At this time, the production of inducible nitric oxide synthase (iNOS) by granulocytes in the liver was evident. These results suggest that neonatal granulocytosis is a postpartum event which results from various stresses (e.g., oxygen stress) at birth. This event may be responsible for such well-known neonatal phenomena as the termination of fetal hematopoiesis in the liver and as neonatal jaundice.

IgA nephropathy-specific expression of the IgA Fc receptors (CD89) on blood phagocytic cells.

We analysed the biochemical features of receptors for the Fc-region of IgA (Fc alphaR, CD89) on blood monocytes and granulocytes of patients with IgA nephropathy (IgAN). Fc alphaR on monocytes of IgAN were found to have a higher Mr (60-80 kD) than those of control monocytes (50-75 kD) and granulocytes (55-75 kD) in both IgAN and controls as shown by immunoprecipitation analysis. Removal of N-linked carbohydrates from Fc alphaR on monocytes of IgAN revealed a 32-36 kD protein core, the Mr of which was still higher than that of controls (28-32 kD). When Fc alphaR transcripts were analysed by reverse-transcription-PCR, only one prominent band was visualized in PCR products from IgAN monocytes. Since the results thus far show that IgAN monocytes express Fc alphaR protein and mRNA differently from granulocytes and control monocytes, PCR products were then cloned and sequenced. The predominant band in PCR products from IgAN monocytes was identical to that of the Fc alphaR a.1 transcript, and an additional 10 transcripts containing five novel transcripts were obtained from granulocytes and control monocytes. In three transcripts, we found an insertion sequence between the S2 and EC1 domains, suggesting the existence of a new exon. These results suggest a predominant usage of Fc alphaR a.1 among various transcripts of Fc alphaR in IgAN monocytes.

Requirement of IL-4 and liver NK1+ T cells for concanavalin A-induced hepatic injury in mice.

Con A-induced hepatic injury of mice accompanied by elevated transaminase was inhibited after in vivo depletion of liver NK cells and NK1+ T cells with intermediate TCR by anti-NK1 Ab or anti-IL-2Rbeta Ab. However, depletion of liver NK cells alone by anti-asialo-GM1 Ab did not inhibit hepatic injury. Although depletion of NK1+ T cells inhibited Con A-induced IL-2R expression of CD4+ high TCR (TCRhigh) cells and IL-4 mRNA expression of hepatic mononuclear cells, exogenous IL-4 engendered Con A-induced hepatic injury and endowed the expression of IL-2R of CD4+ TCRhigh cells. It was also found that in vivo treatment with anti-IL-4 Ab before Con A administration inhibited Con A-induced hepatic injury. In addition, although Con A did not induce hepatic injury in MHC class I-deficient mice, exogenous IL-4 again engendered severe hepatic injury in these mice. Further, while serum TNF-alpha levels induced by Con A were greatly decreased in NK1+ T cell-depleted mice and class I-deficient mice, TNF-alpha levels were recovered by exogenous IL-4. These findings reveal that although CD4+ TCRhigh cells in the liver and their production of TNF-alpha are the direct effectors of Con A-induced hepatic injury, liver NK1+ T cells also play an important role in this hepatitis model. Con A hepatitis may serve as an experimental model for human autoimmune hepatitis.

Identification of nicotinic acetylcholine receptors on lymphocytes in the periphery as well as thymus in mice.

The existence of nicotinic acetylcholine receptors (nAChR) on lymphocytes remains controversial. We attempted to show the existence of nAChR on murine lymphocytes. The intraperitoneal injection of nicotine induced the lymphocytosis in the spleen on day 3. Although freshly isolated lymphocytes bound small quantities of fluorescein isothiocyanate (FITC)-conjugated alpha-bungarotoxin (alpha BuTx), they began to bind alpha BuTx after incubation in medium. In contrast to granulocytes, various lymphocyte subsets obtained from various lymphoid organs were found to bind alpha BuTx. Affinity purification of alpha BuTx-binding protein revealed that lymphocytes expressed the same nAChR molecules as those of muscle. Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis showed that lymphocytes expressed the alpha-subunit mRNA of nAChR. These results suggest that lymphocytes carry nAChR on the surface and are stimulated directly via their nAChR by parasympathetic nerve stimuli.