[Differential diagnosis and surgical management in chondrosarcoma of the jugular foramen].

Objective: To explore the diagnosis, surgical management and outcome of jugular foramen chondrosarcoma (CSA). Methods: Fifteen patients with jugular foramen CSA hospitalized in the Department of Otorhinolaryngology Head and Neck Surgery of Chinese PLA General Hospital from December 2002 to February 2020 were retrospectively collected,of whom 2 were male and 13 were female, aging from 22 to 61 years old. The clinical symptoms and signs, imaging features, differential diagnosis, surgical approaches, function of facial nerve and cranial nerves IX to XII, and surgical outcomes were analyzed. Results: Patients with jugular foramen CSA mainly presented with facial paralysis, hearing loss, hoarseness, cough, tinnitus and local mass. Computed tomography (CT) and magnetic resonance (MR) could provide important information for diagnosis. CT showed irregular destruction on bone margin of the jugular foramen. MR demonstrated iso or hypointense on T1WI, hyperintense on T2WI and heterogeneous contrast-enhancement. Surgical approaches were chosen upon the sizes and scopes of the tumors. Inferior temporal fossa A approach was adopted in 12 cases, inferior temporal fossa B approach in 2 cases and mastoid combined parotid approach in 1 case. Five patients with facial nerve involved received great auricular nerve graft. The House Brackmann (H-B) grading scale was used to evaluate the facial nerve function. Preoperative facial nerve function ranked grade Ⅴ in 4 cases and grade Ⅵ in 1 case. Postoperative facial nerve function improved to grade Ⅲ in 2 cases and grade Ⅵ in 3 cases. Five patients presented with cranial nerves Ⅸ and Ⅹ palsies. Hoarseness and cough of 2 cases improved after operation, while the other 3 cases did not. All the patients were diagnosed CSA by histopathology and immunohistochemistry, with immunohistochemical staining showing vimentin and S-100 positive, but cytokeratin negative in tumor cells. All patients survived during 28 to 234 months' follow-up. Two patients suffered from tumor recurrence 7 years after surgery and received revision surgery. No complications such as cerebrospinal fluid leakage and intracranial infection occurred after operation. Conclusions: Jugular foramen CSA lacks characteristic symptoms or signs. Imaging is helpful to differential diagnosis. Surgery is the primary treatment of jugular foramen CSA. Patients with facial paralysis should receive surgery in time as to restore the facial nerve. Long-term follow-up is necessary after surgery in case of recurrence.

[Pancreatic pseudocyst after pegaspargase treatment in six children].

Objective: To investigate the clinical characteristics and treatment of pancreatic pseudocyst after pegaspargase treatment in children. Methods: The clinical data of 6 children with pancreatic pseudocyst after pegaspargase treatment in the Department of Pediatrics in Peking University Third Hospital from July 2018 to February 2021 were analyzed retrospectively. Results: There were 4 males and 2 females, and their age of onset was 9.5 (5.8, 13.0) years. The total number of pegaspargase applications was 2.5 (2.0, 3.5) times. The course from the last dose of pegaspargase to the onset of pancreatitis was 11.0 (9.0, 17.2) days, and 42.5 (35.0, 129.5) days from the onset of pancreatitis to the diagnosis of pancreatic pseudocyst. Abdominal pain was the most prominent manifestation of pancreatitis (6/6). All of the 6 children were asymptomatic when pancreatic pseudocyst was noted, and were treated conservatively at first, but one case later developed intermittent abdominal distension or nausea after eating. All the cases had pancreatic pseudocyst enlargement during the conservative treatment. Three children were treated with endoscopic ultrasound-guided transgastric drainage, and the cyst disappeared from 10 days to 4 months after the operation. The other 3 children received endoscopic retrograde cholangiopancreatography (ERCP)-guided transpapillary drainage, but one of them turned to surgery due to pancreatic duct stricture, and in the rest 2 children the cyst disappeared at 1 and 3 months after operation respectively. Regarding safety issues, 1 child who received ERCP-guided transpapillary drainage had acute postoperative pancreatitis, which were improved after treatment, and the other 5 had no complications. Conclusions: Pancreatic pseudocyst after pegaspargase chemotherapy can be asymptomatic in the early stage, and should be diagnosed with a history of pegaspargase treatment and timely imaging examination. Conservative treatment is the first choice for asymptomatic pseudocyst. When the pseudocyst enlarges, different endoscopic drainage treatments are required according to whether the pseudocyst is connected with the main pancreatic duct.

[Effect of oral administration of branched-chain amino acids supplementation on the mortality of patients with hepatocellular carcinoma: a meta-analysis].

Objective: To investigate the effect of oral administration of branched-chain amino acids (BCAA) supplementation on the mortality of patients with hepatocellular carcinoma (HCC) after treatment. Methods: Computer searching of PubMed, Embase, Cochrane Library, China National Knowledge Infrastructure (CNKI), Wanfang, and Chinese Biomedical Literature Database was conducted to search for clinical controlled trials and randomized controlled trials (RCTs) on the effect of oral administration of BCAA on the mortality of patients with HCC. The retrieval time limit was from the time of the establishment of each database to December 30, 2019. Two researchers independently screened the literature and extracted the data. Another researcher assessed the risk of bias in the included studies and then used RevMan 5.3 software for meta-analysis. Results: A total of 14 studies were included with 1 179 patients. The overall results showed that oral administration of BCAA had no significant effect on the mortality of HCC patients at 1 year after treatment (RR=0.85, 95%CI:0.68-1.06, P=0.16), while the mortalities of patients at 3 years (RR=0.73, 95%CI: 0.61-0.88, P=0.000 7) and 5 years (RR=0.57, 95%CI:0.34-0.96, P=0.03) after treatment were significantly lower than those of the control group. The subgroup analysis showed that for radiofrequency ablation (RFA) patients, there was no significant difference in 1-year mortality between the BCAA group and the control group (RR=0.96, 95%CI:0.14-6.5, P=0.97), while 3-year mortality was significantly reduced (RR=0.59, 95%CI:0.43-0.81, P=0.001); for hepatectomy patients, there was no significant differences in 1 -and 3-year mortality between the two groups (RR=0.90, 95%CI:0.44-1.88, P=0.79; RR=0.97, 95%CI:0.71-1.33, P=0.85, respectively). In addition, as for albumin levels, BCAA supplementation significantly increased albumin levels without considering the treatment of HCC (SD=0.45, 95%CI: 0.29-0.90; P=0.000 1), but had no significant effect on hepatectomy patients (SD=0, 95%CI: -0.41-0.41, P=0.99). Conclusion: BCAA supplementation might improve liver reserve function and long-term prognosis of HCC patients, which was related to the surgical method. Supplementing BCAA reduced the long-term mortality of RFA patients, but had no significant effect on hepatectomy patients.

[Clinical study of psychological changes and post traumatic stress disorder in elderly patients with hip fracture].

Objective: To explore the psychological state and affected factors of elderly patients with hip fractures. Methods: A retrospective analysis of 156 elderly hip fracture patients(>65 years) admitted to the Department of Orthopaedics, the First Affiliated Hospital of Harbin Medical University from January 2016 to August 2019 was performed. General and psychological information were collected by questionnaire.General information included age, gender, education, whether surgery, length of stay.SCL-90, a self-assessment scale, was chosen as the psychological test to analyzed the elderly hip fracture patients' psychological status during hospitalization and the norms of SCL-90 in Chinese which were established in 1986 were used as the control group. The prognostic factors were examined by univariate and multivariate analysis. Results: Somatization, interpersonal sensitivity, depression, anxiety, paranoid factor scores, and total scores of the elderly hip fracture patients were significantly higher than control group(all P=0.00).Univariate analysis and logistic regression analysis showed that non-surgery treatment and more than 10 days of hospitalization were independent prognostic factors that affected the psychological state of elderly hip fracture patients (all P=0.00). Conclusion: Elderly patients hospitalized with osteoporosis and hip fractures are prone to have negative emotional and psychological changes.The length of hospitalization and the choice of treatment can affect patients' psychological state, suggesting that effective psychological intervention is necessary.

Sensitive electrochemical enzyme immunoassay microdevice based on architecture of dual ring electrodes with a sensing cavity chamber.

A novel electrochemical detection architecture was investigated for enzyme immunoassay sensors. Microchips with dual-ring working and counter electrodes, and a sensing cavity chamber were made on glass slides. The glass surface of the microchip was coated by 3-aminopropyltriethoxysilane (APTES). Goat IgG, as a example, was covalently captured on APTES-modified glass surfaces through glutaraldehyde (GA) as a cross-linker. Enzyme substrate, p-aminophenyl phosphate (PAPP) was prepared by electrolysis. The enzyme conversion from home-synthetic PAPP to p-aminophenol (PAP) was examined by differential pulse voltammetry (DPV). A competitive inhibition enzyme-linked immunosorbant assay (ELISA) was designed to test the system. Experimental results demonstrate that a detection limit of 118 fg/ml of goat IgG and a dynamic range of 118 fg/ml to 1.18 ng/ml, up to five orders of magnitude could be achieved. Due to its novel architecture design and electronic detection scheme, the method can be used to fabricate portable electrochemical ELISA lab-on-chip systems. The technology could have great potential in clinical diagnostic applications.

Vaccination with dendritic cells pulsed in vitro with tumor antigen conjugated to cholera toxin efficiently induces specific tumoricidal CD8+ cytotoxic lymphocytes dependent on cyclic AMP activation of dendritic cells.

We investigated the development of CD8+ tumor-specific cytotoxic lymphocytes (CTL) and protection against tumor growth after vaccination with bone marrow-derived dendritic cells (DC) pulsed with a model protein ovalbumin conjugated to cholera toxin (OVA-CT) in B6 mice using E.G7 tumor cells expressing OVA(257-264) peptide (SIINFEKL) as target cells in vitro and in vivo. Vaccination with OVA-CT-pulsed DC concurrently induced strong CTL in vitro activity and anti-E.G7 tumor protection in vivo in WT, NK-depleted and CD4-deficient mice as well as in IL-12-/- and IFN-gamma-/- mice but not in CD8-deficient mice. Importantly, activation of CTL by OVA-CT-pulsed DC was dependent on CT-induced activation of adenylate cyclase and increased cAMP production by DC associated with increased expression of MHC class I and co-stimulatory molecules (CD80, CD86 and CD40). These results show that vaccination with DC pulsed with antigens (Ag) conjugated to CT induces a strong CTL response and suggest that conjugation of tumor Ag to CT for DC vaccination represents a promising approach for tumor vaccination and immunotherapy.

Nasal administration of Schistosoma mansoni egg antigen-cholera B subunit conjugate suppresses hepatic granuloma formation and reduces mortality in S. mansoni-infected mice.

Granulomatous inflammation in schistosomiasis is a delayed-type hypersensitivity reaction mediated by CD4+ T cells specific for parasite egg antigens (Ags). In an attempt to control T-cell responses leading to excessive harmful inflammation and granuloma formation, especially in the liver, BALB/c mice were intranasally (i.n.) treated with soluble Schistosoma mansoni egg Ags (SEA) conjugated to cholera toxin B subunit (CTB), a mucosa-binding protein with demonstrated capacity to suppress inflammatory T-cell functions after mucosal administration. Treatment with CTB-SEA significantly conjugate a reduced liver granuloma formation in infected mice associated with decreased SEA specific Th1- and Th2-type immune responses by liver leukocytes. Importantly, treatment with CTB-SEA conjugate also significantly reduced the mortality in chronically infected mice. In S. mansoni-infected large-granuloma forming CBA mice, i.n. treatment with purified Sm-p40, the major egg antigen, conjugated to CTB likewise significantly inhibited hepatic egg granuloma formation. A reduction of SEA-driven lymphoproliferation and of interferon (IFN)-gamma, interleukin (IL)-4 and IL-5 production, together with an increase in transforming growth factor (TGF)-beta1 production, were observed in splenic cells from CTB-Sm-p40-treated SEA-sensitized mice, as well as in liver leukocytes from CTB-Sm-p40-treated schistosome-infected mice. These results indicate that mucosal administration of SEA or purified Sm-p40 antigen in conjunction with CTB is highly effective in curtailing immunopathologic manifestations of schistosomiasis in vivo in infected hosts.

Oral administration of cholera toxin B subunit conjugated to myelin basic protein protects against experimental autoimmune encephalomyelitis by inducing transforming growth factor-beta-secreting cells and suppressing chemokine expression.

The efficacy and mechanism of immunosuppression against experimental autoimmune encephalomyelitis (EAE) by oral low-dose administration of myelin basic protein (MBP) conjugated to cholera toxin B subunit (CTB) were investigated in Lewis rats immunized with MBP together with complete Freund's adjuvant 4 days before the start of treatment. Oral treatment with CTB-MBP conjugate gave almost complete protection against disease, an effect that was totally abrogated by including a low dose of cholera holotoxin (CT). The protection by CTB-MBP was associated with a dramatic reduction in the number of leukocytes staining for CD4, CD8, IL-2R or MHC class II in the spinal cord as examined by immunohistochemistry. The mRNA expressions of T(h)1 cytokines IFN-gamma, IL-12 and tumor necrosis factor-alpha, as well as of chemokines monocyte chemotactic protein (MCP)-1 and RANTES in the spinal cord were also reduced by 76-94%, as assessed by in situ hybridization. In contrast, transforming growth factor (TGF)-beta mRNA-expressing cells were strongly increased in the spinal cord from animals treated orally with the CTB-MBP conjugate. In the draining peripheral lymph nodes, the number of MBP-specific TGF-beta mRNA-expressing cells was also increased, whereas there was a decrease in cells expressing T(h)1 or T(h)2 cytokine mRNA. Protection against EAE could be transferred by injection of cells from the mesenteric lymph nodes of animals fed with CTB-MBP into naive animals exposed to encephalitogenic T cells. The results indicate that the protective anti-inflammatory effect by oral treatment with CTB-MBP conjugate is, to a large extent, due to the induction of TGF-beta-secreting suppressive-regulatory T cells and to local down-regulation of MCP-1 and RANTES in the spinal cord.

Intranasal administration of a Schistosoma mansoni glutathione S-transferase-cholera toxoid conjugate vaccine evokes antiparasitic and antipathological immunity in mice.

Mucosal administration of Ags linked to cholera toxin B subunit (CTB) can induce both strong mucosal secretory IgA immune responses and peripheral T cell hyporeactivity. In this study, intranasal (i.n. ) administration of CTB-conjugated Schistosoma mansoni 28-kDa GST (CTB-Sm28GST) was found to protect infected animals from schistosomiasis, especially from immunopathological complications associated with chronic inflammation. Worm burden and liver egg counts were reduced in infected animals treated with the CTB-Sm28GST conjugate as compared with mice infected only, or with mice treated with a control (CTB-OVA) conjugate. However, a more striking and consistent effect was that granuloma formations in liver and lungs of mice treated with CTB-Sm28GST were markedly suppressed. Such treatment was associated with reduced systemic delayed-type hypersensitivity and lymphocyte proliferative responses to Sm28GST. Production of IFN-gamma, IL-3, and IL-5 by liver cells was also markedly reduced after i.n. treatment of CTB-Sm28GST, whereas IL-4 production was not impaired. Intranasal treatment of infected mice with CTB-Sm28GST increased IgG1-, IgG2a-, IgA-, and IgE-Ab-forming cell responses in liver in comparison with treatment with CTB-OVA, or free Sm28GST. Most importantly, mucosal treatment with CTB-Sm28GST significantly reduced animal mortality when administered to chronically infected mice. Our results suggest that it may be possible to design a therapeutic vaccine against schistosomiasis that both limits infection and suppresses parasite-induced pathology.

[The experience in the treatment of acute necrotic pancreatis].

24 case patients with acute necrotic pancreatis underwent dynamic CT examination at our hospital from 1990, of those patients suspected of pancreatic infection were performed direct bacteriologic sampling by CT-guided percutaneous aspiration. According to CT and bacterial results, we decided to whether operate or not. Meanwhile, multi-organ monitored and support therapy underwent. ANP mortalities reduced from 20.5% to 12.5%. We suggest that the dynamic CT and CT-guided aspiration is a safe, and rapid technique for distinguishing pancreatic infection from severe sterile pancreatitis, and may prove helpful in reducing the high morbidity and mortality associated with pancreatic infection.

Autoreactive T and B cell responses to myelin antigens after diagnostic sural nerve biopsy.

To study whether nervous tissue trauma provokes myelin antigen autoreactive T and B cell responses in humans we examined consecutive blood samples from 7 patients with polyneuropathy undergoing diagnostic sural nerve biopsy and 8 control patients undergoing other types of minor surgery. The antigen-specific T cells were assessed by enumerating cells secreting interferon-gamma (IFN-gamma) in response to the myelin components P0, P2, myelin basic protein (MBP) and myelin associated glycoprotein (MAG), and to 4 selected MBP peptides. B cell mediated immunity was assessed by counting numbers of cells secreting antibodies directed against the myelin proteins. On day 7 after biopsy, there were 3-10-fold increased numbers of T and B cells reactive with P0, P2, MBP and MAG in blood of polyneuropathy patients compared to controls, while levels of cells recognizing purified protein derivate or responding to phytohemagglutinin (PHA) did not differ significantly. Comparison of prebiopsy levels on day 0 with post-biopsy levels on day 7 in the polyneuropathy patients revealed a significant increase in T cells recognizing P0, P2 and MAG, and in B cells secreting IgG antibodies against P0 and P2. On day 14 after nerve biopsy these differences were no longer seen. We suggest that in patients with polyneuropathy, sural nerve biopsy with the ensuing wallerian degeneration and myelin breakdown causes transiently increased levels of circulating myelin autoreactive T and B cells. It remains to be determined if this has a physiological role in nerve trauma responses and/or affects the clinicopathological course of the peripheral neuropathy.

T cells recognizing multiple peptides of myelin basic protein are found in blood and enriched in cerebrospinal fluid in optic neuritis and multiple sclerosis.

The cause of multiple sclerosis (MS) is unknown. Recently reported abnormal T-cell responses to several myelin proteins and myelin basic protein (MBP) peptides in peripheral blood constitute one line of evidence that autoimmune mechanisms could be involved in the pathogenesis of the disease. Monosymptomatic unilateral optic neuritis (ON) is a common first manifestation of MS and important to examine for a possible restriction of the T-cell repertoire early in the disease. T-cell activities to MBP and the MBP amino acid sequences 63-88, 110-128 and 148-165 were examined by short-term cultures of mononuclear cells from cerebrospinal fluid (CSF) and blood in the presence of these antigens, and subsequent detection and counting of antigen-specific T cells that responded by interferon-gamma (IFN-gamma) secretion. Most patients with MS and ON had MBP and MBP peptide-reactive T cells in CSF, amounting to mean values of between about 1 per 2000 and 1 per 7000 CSF cells and without immunodominance for any of the peptides. Numbers were 10-fold to 100-fold lower in the patients' blood. Values were similar in ON and MS, and no evidence was obtained for a more restricted T-cell repertoire in ON. The MBP peptide-recognizing T-cell repertoire was different in CSF than in blood in individual patients with ON and MS, thereby giving further evidence for an autonomy of the autoimmune T-cell response in the CSF compartment. No relations were observed between numbers of autoreactive T cells and presence of oligoclonal IgG bands in CSF or abnormalities on magnetic resonance imaging of the brain in ON or clinical variables of MS. The high numbers of MBP and MBP peptide-reactive T cells could play a role in the pathogenesis of ON via secretion of effector molecules, one of them being IFN-gamma, as well as in the transfer of ON to MS.

Autoreactive T and B cells in nervous system diseases.

BACKGROUND: Abnormal autoimmunity could play a role in the pathogenesis of multiple sclerosis (MS), in analogy with its model experimental allergic encephalomyelitis (EAE) which can be transferred by T cell lines directed to myelin basic protein (MBP) and myelin proteolipid protein (PLP), and worsened with antibody to myelin oligodendrocyte glycoprotein (MOG). Whether T and B cell reactivities to these autoantigens, and to myelin-associated glycoprotein (MAG) which is another possible target for autoimmune attack, occur in MS and then especially in the cerebrospinal fluid (CSF) with its close relation to the nervous tissue, is not clear. Myasthenia gravis, a prototype for autoimmune disease in humans, is characterized by IgG antibodies to acetylcholine receptor (AChR) in serum, but it is not known whether an augmented T cell response to AChR occurs in this disease. Nerve trauma has been speculated upon to be associated with exacerbations of MS; if nerve trauma recruits augmented autoimmune T and B cell responses is not known. High numbers of anti-myelin protein and anti-AChR antibody secreting cells have been described in cord blood, but whether corresponding T cell reactivities occur remains to be settled. METHODS: Antigen specific T cell responses in blood and CSF are studied regarding specificity, quantity and functional differentiation by counting numbers of cells which, upon antigen stimulation, respond by secretion of interferon-gamma (IFN-gamma). Similarly, the B cell responses to autoantigens are evaluated by counting cells which, in presence of antigen, secrete specific antibodies of IgG, IgA and IgM isotypes. RESULTS: MS is characterized by elevated numbers of T cells recognizing MBP, PLP, MAG and MOG as well as the synthetic MBP amino acid sequences 1-20, 63-88, 89-101, 96-118, 110-128 and 148-165, without immunodominance for any of these components. PLP, MOG and MAG reactive T cells are strongly enriched in the patients' CSF, as previously also shown for MBP reactive T cells. Similarly, elevated numbers of B cells with these specificities and enriched in CSF were found in MS. No preferential autoimmune T cell response was apparent after subdivision of the MS patients according to their HLA-DR genotype. A majority of patients with myasthenia gravis had AChR and alpha-subunit reactive T cells in peripheral blood, and also anti-AChR antibody secreting cells of the IgG, less frequently IgA and IgM isotypes. Peripheral nerve trauma in form of diagnostic sural nerve biopsy is accompanied by transient elevation in blood of T cells recognizing MBP and MAG which are common to the central and peripheral nervous system, and to the peripheral nerve myelin proteins P0 and P2. Myelin protein and AChR reactive T and B cells occur also in patients with other neurological diseases and tension headache, and in healthy subjects, but less frequently and at lower numbers than in MS and myasthenia gravis, respectively. Cord blood contains higher numbers of myelin protein and AChR reactive T cells in comparison with blood from healthy adults. CONCLUSION: Antigen-specific T cells recognizing multiple myelin proteins and MBP peptides constitute a regular finding in MS. These autoimmune T cells are strongly enriched in CSF. In myasthenia gravis, increased levels of AChR and alpha-subunit reactive T cells as well as anti-AChR IgG, less frequently IgA and IgM antibody secreting cells can be demonstrated in most patients. T and B cells with the mentioned specificities can also be identified in patients with tension headache and healthy subjects but less frequently and at lower numbers, and they are assumed to reflect normally occurring autoimmune T and B cell repertoires. These are augmented after nerve trauma and in the newborn...

The T-cell repertoire in myasthenia gravis involves multiple cholinergic receptor epitopes.

Antibodies against the alpha-subunit of the acetylcholine receptor (AChR) are found in most patients with myasthenia gravis and are considered to contribute to the receptor damage which leads to the characteristic signs and symptoms of the disease. This B-cell response is T-cell driven. Elevated T-cell reactivities to AChR and its alpha-subunit have been described in myasthenia gravis, and AChR alpha-subunit peptide reactive T-cell lines and clones preferentially recognizing certain defined sequence segments have been reported, thereby disclosing the possibility of specific immunotherapy. We have defined the T-cell repertoire to AChR, its alpha-subunit and the synthetic peptide sequences 100-117, 113-130, 143-163, 161-179, 207-225, 221-240, and 235-255 of the alpha-subunit in an immunospot assay which is based on secretion of interferon-gamma (IFN-gamma) by individual memory T cells upon stimulation with specific antigen in short-term cultures. Most patients with myasthenia gravis displayed T-cell reactivities to 1 to 6 different peptides. The mean numbers of T cells recognizing individual peptides varied in the myasthenia gravis patients between 1 per 77,000 and 1 per 167,000 peripheral blood mononuclear cells. None of the seven peptides evaluated could be identified as an immunodominant T-cell epitope, and any of them was found to dominate in individual patients. The numbers of T cells reacting with AChR and recombinant human AChR alpha-subunit were slightly higher (mean numbers 1 per 26,000 and 1 per 50,000 mononuclear cells, respectively). Such cells, as well as AChR alpha-subunit peptide reactive T cells, were also found in patients with other neurological diseases and in healthy subjects, but at lower frequencies and numbers. In myasthenia gravis, the elevated numbers of memory T cells recognizing multiple AChR alpha-subunit peptides may be crucial for the development of the disease, and the IFN-gamma released by such T cells might be important for its perpetuation.

Myasthenia gravis: T and B cell reactivities to the beta-bungarotoxin binding protein presynaptic membrane receptor.

Antibodies against acetylcholine receptor (AChR) can be detected in most patients with myasthenia gravis (MG) and are considered to be involved in the immunopathogenesis of this disease. AChR are isolated from crude receptor preparations by binding to alpha-bungarotoxin (alpha-BuTx). Patients with MG have also antibodies against a second protein tentatively named presynaptic membrane receptor (PsmR), which has been isolated from crude receptor utilizing beta-bungarotoxin (beta-BuTx). PsmR could represent another antigen besides AChR relevant for the development of MG. We have now evaluated the T cell reactivity to PsmR in MG and controls by analysing the frequencies of cells which in response to PsmR in short-term cultures secreted interferon-gamma (IFN-gamma). The B cell response to PsmR was analysed in parallel by counting cells secreting anti-PsmR antibodies. Most patients with MG had PsmR reactive T cell in blood with a median number of about 1 per 44,000 mononuclear cells. Cells secreting anti-PsmR antibodies belonging to the IgG and IgA isotypes, less frequently of the IgM isotype were detected in most MG patients. A positive correlation was found between T cells reactive with PsmR and anti-PsmR IgG antibody secreting cells. PsmR reactive T and B cells were also detected in control patients, but at much lower numbers. Our results indicate that MG is accompanied by T as well as B cell responses to PsmR, in addition to the previously recognized responses to AChR. It remains to be shown whether these PsmR reactivities are of pathogenetic importance in MG.

T cell responses to human recombinant acetylcholine receptor-alpha subunit in myasthenia gravis and controls.

Antibodies against the nicotinic acetylcholine receptor (AChR) of the neuromuscular junction are detectable in most patients with myasthenia gravis (MG) and assumed to participate in the destruction of the AChR, thereby, causing the characteristics signs and symptoms of the disease. The extent and importance of T cell responses to AChR and its subunits in MG are still unsettled. We have now examined T cell reactivities using human recombinant AChR-alpha subunit as antigen. Upon recognition of appropriate antigen in an MHC-class II-restricted fashion, memory T cells secrete interferon-gamma (IFN-gamma). Adopting this principle in an immunospot assay we found that 73% of MG patients had recombinant human AChR-alpha subunit-reactive T cells at a median value of 1 per 56,000 blood mononuclear cells, while only 27% of the MG patients responded to the alpha subunit in a conventional lymphocyte proliferation assay. This compares with even lower numbers of AChR-reactive T cells and 14% positivity in the proliferation assay among control subjects. The T cell responses to the control antigens purified protein derivative and myelin basic protein did not differ between MG and controls, underlining the specificity of an augmented T cell reactivity to AChR-alpha subunit in MG. Alpha Subunit-specific T cell lines and clones propagated from patients with MG and healthy controls yielded a high proportion of alpha subunit-reactive T cells in the IFN-gamma immunospot assay. Their appearance was inhibited by the addition of monoclonal anti-MHC class II antibodies, demonstrating that an MHC-restricted T cell response was measured. Our data underline that the AChR-alpha subunit is a major T cell autoantigen in MG.

Effect of low-dose radiation on repair of DNA and chromosome damage.

In this report results of studies on the effect of different doses of low LET (linear energy transfer) radiations on the unscheduled DNA synthesis (UDS) and DNA polymerase activity as well as the induction of adaptive response in bone marrow cells (BMC) by low dose radiation were presented. It was found that whole-body irradiation (WBI) with X-ray doses above 0.5 Gy caused a dose-dependent depression of both UD5 and DNA polymerase activity, while low dose radiation below 250 mGy could stimulate the DNA repair synthesis and the enzyme activity. WBI of mice with low doses of X-rays in the range of 2-100 mGy at a dose rate of 57.3 mGy per minute induced an adaptive response in the BMC expressed as a reduction of chromosome aberrations following a second exposure to a larger dose (0.65 mGy). It was demonstrated that the magnitude of the adaptive response seemed to be inversely related to the induction dose. The possibility of induction of adaptive response in GO phase of the cell cycle and the possibility of a second induction of the adaptive response were discussed.

Radiation hormesis: its expression in the immune system.

The effects of low-dose single and continuous whole-body irradiation on immune functions were studied in C57BL/6 mice. Plaque-forming cell reaction of the spleen was found to be stimulated by single doses of x rays in the range of 0.025 to 0.075 Gy and by continuous exposure to gamma rays with a cumulative dose of 0.065 Gy. The reactivity of thymocytes to interleukin 1 showed a dose-dependent depression in the dose range of 0.025 to 0.25 Gy, but there was an increase in cell number in the thymus between doses of 0.025 and 0.10 Gy, resulting in enhancement of reaction of the whole organ. Unscheduled DNA synthesis of spleen cells was stimulated by single irradiation with 0.05 Gy and continuous irradiation with a cumulative dose of 0.13 Gy. The implications of these immunologic changes under low-dose radiation are discussed.