IFN—γ,IL—4,TGF—β在诱导EAMG耐受中的作用

目的为探讨鼻腔耐受和 Wistar大鼠对 EAMG耐受的机制。方法用放射标记的 c DNA寡核苷酸作探针原位杂交计数免疫后第 7周表达 IFN-γ、IL - 4和 TGF-β m RNA的 MNC。结果 EAMG大鼠 PIL N和脾脏中 IFN-γ m RNA表达细胞数比 CFA大鼠高 (P<0 .0 5 ) ;鼻腔耐受大鼠 PIL N中 IFN-γ和 IL - 4m RNA表达细胞数比 EAMG大鼠低 ,PIL N、脾脏和胸腺中 TGF-β m RNA表达细胞数比 EAMG大鼠高 (P<0 .0 5 ) ;WF大鼠 PIL N中 IFN-γ m RNA表达细胞数比 EAMG大鼠低 ,TGF- β m RNA表达细胞数比 EAMG大鼠高 (P<0 .0 5 )。结论 IFΝ- γ表达增高与 EAMG发生有关 ,IFN- γ表达降低 TGF- β表达增高与 EAMG耐受有关 ;TGF- β表达增高在 EAMG耐受中起重要作用。     

未成熟树突状细胞诱导实验性自身免疫性重症肌无力耐受的试验研究

目的 探讨未成熟树突状细胞(iDC)对实验性自身免疫性重症肌无力(EAMG)的影响。方法 用小剂量粒-巨噬细胞集落刺激因子(GM-CSF)体外诱导骨髓前体细胞，获得的iDC用乙酰胆碱受体(ACAR)负载后皮下接种同基因大鼠，3周后通过体外试验观察脾细胞对AChR的增殖反应，同时用AChR和完全弗氏佐剂(CFA)免疫大鼠，观察免疫7周后MG相关指标的改变。结果 小剂量GMCSF诱导所获得的iDC与成熟DC(mDC)相比，其表面MHCⅡ和共刺激分子CD80、CD86的表达低，摄取dextran-FITC的能力强但刺激同种T细胞增殖的能力弱。接种iDC、mDC、AChR负载的mDC的大鼠和对照组一样，体外脾细胞对AChR的刺激均强烈增殖，用AChR和CFA免疫后，产生明显的MG症状，重复电刺激出现明显衰减，血清AChRAb滴度明显增高，神经肌肉接头呈现典型的MG样改变；而接种AChR负载的iDC的大鼠脾细胞对AChR的刺激呈现明显的增殖抑制但对卵清蛋白的刺激仍强烈增殖，MG相关指标均未见明显改变。结论 骨髓前体细胞经小剂量GM-CSF诱导产生了iDC，AChR负载的iDC可诱导EAMG耐受。     

重肌灵片治疗重症肌无力的免疫调节机理研究

目的：探讨重肌灵片的免疫调节机制。方法：采用正常小鼠、免疫抑制模型小鼠和EAMG大鼠模型观察重肌灵片的免疫调节作用。结果：重肌灵片增强ConA或LPS诱导的正常小鼠及免疫抑制模型小鼠T、B细胞的增殖，促进1L-2分泌；能对抗ConA诱导的EAMG大鼠淋巴细胞增殖的降低；但抑制AChR诱导的淋巴细胞增殖及IFN-γ、IL-4mRNA的表达；此外，能显著促进EAMG大鼠CD4^＋T淋巴细胞的凋亡。结论：重肌灵片增强正常小鼠、免疫抑制小鼠和EAMG大鼠的免疫功能，但抑制AChR诱导的特异性的T细胞增殖及IFN-γ、IL4mRNA的表达，该作用可能是通过诱导AChR特异性的CD4^＋T细胞凋亡实现的。     

SIN-1降低重症肌无力大鼠的自身免疫反应

用一氧化氮 (NO)供体 3 吗啉 斯德酮亚胺 (SIN 1)干预乙酰胆碱受体 (AChR)致敏的实验性自身免疫性重症肌无力 (EAMG)大鼠模型。并进行临床评分、体重测量、免疫学指标及细胞凋亡检测。结果显示在大鼠致敏后 0～ 7天和 16～ 2 5天给药后 ,SIN 1组大鼠临床症状明显减轻伴发病延迟 ,血清IgG含量始终明显低于对照组 ;致敏后第10天 ,SIN 1组大鼠脾单个核细胞AChR反应性IFN γ分泌性细胞数 (6 38± 1 0 6 )比对照组 (8 2 5± 1 6 7)明显减少(P <0 0 5 ) ,外周血AChR反应性凋亡细胞含量 (8 5 9± 1 35 )与对照组 (5 0 5± 0 6 3)相比明显增多 (P <0 0 1)。实验证明SIN 1可以促使AChR反应性MNC凋亡增加 ,下调自身免疫反应 ,在EAMG的发病和疾病进展中起保护作用。     

升陷汤治疗实验性自身免疫性重症肌无力大鼠免疫机制研究

目的:探讨升陷汤治疗实验性自身免疫性重症肌无力(EAMG)大鼠的免疫机制。方法:采用人工合成鼠源乙酰胆碱受体琢亚基97鄄116 肽段加完全弗氏佐剂免疫Lewis 大鼠构建EAMG,经评估确定建模成功25 只。将这25 只大鼠随机分为模型对照组,阳性药物组(强的松组),升陷汤低、中、高剂量组。观察该方对模型大鼠临床评分、体重、低频重复电刺激(RNS,5 Hz)衰减率、血清中乙酰胆碱抗体(AChR Ab)含量及TGF、IFNβ、IL-2、IL-4 和IL-17 水平的影响。结果:造模后各组较佐剂对照组RNS 衰减率明显增大(P<0.01 或P<0.05),且均超过10%,体重进行性下降,并出现典型肌无力样症状,证明造模成功。给药治疗后,升陷汤低、中、高剂量组大鼠RNS 衰减率均显著降低(P<0.01),体重下降均减缓,症状好转。与模型对照组相比,升陷汤低、中、高剂量组血清AChR Ab 含量均降低(P<0.05),TGFβ水平均升高,IFN、IL-2、IL-4 和IL-17 水平均降低(P<0.01 或P<0.05)。结论:升陷汤可使RNS 衰减好转,改善EAMG 大鼠体重持续下降趋势,并使体重增加趋势升高,其机制可能是上调TGFβ1水平,下调IFN、IL-2、IL-4 和IL-17 的水平,抑制B 细胞产生AChR Ab,降低血清AChR Ab 含量,减少对NMJ 处AChR 的损害,从而起到治疗EAMG 的作用。     

鼻息肉组织T淋巴细胞IFN-γ、IL-4的表达

目的:通过检测γ-干扰素(IFN-γ)、白细胞介素-4(IL-4)两种细胞因子在鼻息肉组织T淋巴细胞(CD3⁺细胞)中的表达, 探讨鼻息肉的可能发病机制。方法:采用流式细胞术检测21例鼻息肉患者鼻息肉组织、外周血中T淋巴细胞IFN-γ、IL-4的分泌情况, 并与正常人下鼻甲粘膜及外周血进行比较。 结果:在正常人下鼻甲粘膜中几乎未见CD3⁺IL-4⁺和CD3⁺IFN-γ⁺细胞。鼻息肉组织中有大量T淋巴细胞浸润, IL-4、IFN-γ的含量分别为(13.606±0.644)%、(32.938±2.477)%;患者外周血中IL-4、IFN-γ的含量分别为(6.686±0.204)%、(64.312±1.611)%, 与之相比, 病人鼻息肉组织中IL-4的含量显著高于外周血(P＜0.05)而IFN-γ的含量明显低于外周血(P＜0.05)。正常人外周血IL-4、IFN-γ的含量分别为(0.560±0.051)%, (0.246±0.020)%, 与之相比, 病人外周血中IL-4、IFN-γ的含量均显著高于正常人(P＜0.05)。结论:鼻息肉患者鼻粘膜局部免疫异常, Th细胞因子分泌优势发生改变, 造成鼻腔粘膜"微环境"改变, 可能与鼻息肉的形成有密切关系。     

NK1.1+细胞在实验性自身免疫性重症肌无力疾病发病中的免疫调节作用

目的:探讨NK1.1 细胞在实验性自身免疫性重症肌无力(EAMG)疾病发病中的作用以及其调节机制。方法:腹腔注射抗小鼠NK1.1单克隆抗体(mAb)清除C57BL/6(B6)小鼠体内的NK1.1 细胞,建立NK1.1 细胞缺陷小鼠模型;用AChR CFA免疫小鼠诱发EAMG,通过Lennon等的肌无力评分标准分析各组小鼠之间EAMG的发病情况和病情严重程度;应用ELISA法检测单核细胞(MNC)上清液中IFN-γ、IL-4的分泌和表达;应用放射免疫测定法检测血清中AChRIgG含量;用抗IFN-γmAb中和小鼠体内IFN-γ,观察发病情况及血清中AChRIgG的含量。结果:NK1.1 细胞缺陷的小鼠同正常免疫组小鼠相比,发病率和病情严重程度均明显降低(发病率:36%vs86%,P<0.01);免疫后NK1.1 细胞缺陷组和正常免疫组小鼠相比,发病率和病情严重程度无明显统计差异;NK1.1 细胞缺陷降低IFN-γ的表达,但是IL-4的分泌和表达无统计学意义;NK1.1 细胞缺失降低AChR特异性抗体的产生;中和体内IFN-γ后,EAMG的发病率和病情严重程度均减轻,并且AChR特异性抗体减少。结论:NK1.1 细胞在EAMG发病初期发挥重要作用。在EAMG发病中,NK1.1 细胞可以使AChR特异性T细胞产生IFN-γ,增加AChR特异性抗体产生,从而加重EAMG的发病。     

乙型肝炎疫苗联合B7-H1蛋白疫苗对HBV转基因小鼠抗HBsAg免疫应答的影响

目的:研究B7-H1蛋白疫苗对HBV转基因小鼠免疫应答的影响,探索治疗慢性乙型肝炎的新方法。方法:用不同剂量的乙型肝炎疫苗和B7-H1蛋白疫苗联合免疫HBV转基因小鼠,应用ELISA法检测转基因小鼠在不同时间点血清抗B7-H1抗体滴度,同时在免疫后第14周末处死小鼠取脾细胞,检测不同的免疫方法对小鼠脾细胞产生HBsAg特异性Th1类细胞因子(IFN-γ及IL-2)、对HBsAg特异性分泌IFN-γT细胞数量及对小鼠淋巴细胞增殖的影响。结果:成功完成小鼠的免疫计划,5周起血清中即能测到B7-H1抗体,同一时间点各组之间的抗体滴度值并无明显差异。加B7-H1蛋白免疫各组与相同剂量单用HBsAg蛋白免疫各组相比:IL-2均明显减低(P<0.05),分泌IFN-γT的T细胞数量下降,但脾淋巴细胞分泌IFN-γ的水平各组间无明显差异;MTT法测定的淋巴细胞增殖能力各组间也无明显变化。结论:B7-H1蛋白疫苗可诱导HBV转基因小鼠产生明显的抗B7-H1抗体应答,但不能增强抗HBsAg的免疫应答。较小剂量的HBsAg即可引起HBV转基因小鼠Th1类细胞因子(IFN-γ及IL-2)的分泌以及淋巴细胞增殖。     

重肌灵片在重症肌无力小鼠模型T细胞活化中的作用

AchR免疫C57BL/6小鼠建立EAMG小鼠模型,观察重肌灵片在自身免疫性重症肌无力小鼠T细胞活化过程中的作用。结果显示重肌灵片抑制AChR诱导的EAMG小鼠淋巴细胞增殖、DTH反应并降低血清中抗AChR抗体;抑制CD28和CTLA-4的表达、增强CD80和CD86的表达,但对CD40和CD40L的表达无显著影响;并降低Th细胞中表达IFN-γ的阳性细胞数、升高表达IL-4的阳性细胞数。提示重肌灵片显著抑制EAMG小鼠T细胞的活化,其抑制作用可能是通过调节细胞表面协同刺激分子的表达,及抑制Th细胞向Th1极化、促进其向Th2极化实现的。     

大剂量HBsAg疫苗对小鼠细胞免疫应答的调节作用

目的:探讨大剂量HBsAg疫苗对机体细胞免疫应答的影响。方法:不同剂量HBsAg疫苗两次免疫小鼠后, 用氚-胸腺嘧啶核苷(-[H³]TdR)掺入法, ELISA方法分别测定免疫鼠T淋巴细胞增殖能力, 细胞培养上清中白细胞介素-2(IL-2), γ干扰素(IFN-γ)含量及血清中抗HBsIgG2a阳转率。结果:大剂量HBsAg疫苗单次免疫后, 小鼠T淋巴细胞增殖能力显著强于对照组(P＜0.05);Th1型细胞因子IL-2、IFN-γ显著多于对照组(P<0.05);抗HBsIgG2a阳转率显著高于小剂量组(P＜0.01)。加强免疫后, 各项指标增高更显著, 小剂量组才呈现显著性增高。结论:大剂量HBsAg疫苗可诱生特异性细胞免疫应答, 并使细胞免疫趋向Th1型。     

大鼠经鼻腔乙酰胆碱受体耐受诱导的试验研究

用乙酰胆碱受体（ＡＣｈＲ）加完全弗氏佐剂（ＣＦＡ）免疫大鼠前，鼻腔给予ＡＣｈＲ可有效地预防实验性自身免疫性重症肌无力（ＥＡＭＣ）。本文结果表明，与非耐受对照组比，鼻腔ＡＣｈＲ耐受组大鼠免疫后，国窝、腹股沟淋巴结（ＰＩＬＮ）的单个核细胞（ＭＮＣ）ＡＣｈＲ特异的淋巴细胞增殖反应受到明显抑　制，鼻腔耐受组ＰＩＬＮ中ＡＣｈＲ特异的ＣＤ４~＋／ＣＤ８~－克隆增生也明显受抑制，差异均有显著性。此外，鼻腔耐受组ＡＣｈＲ特异性皮肤迟发型过敏反应（ＤＴＨ）也显著降低。提示鼻腔ＡＣｈＲ耐受后引起的特异性Ｔ淋巴细胞反应的低调可能是临床肌无力抑制的基础。     

Cellular mRNA expression of interferon-gamma (IFN-γ), IL-4 and transforming growth factor-beta (TGF-β) in rats nasally tolerized against experimental autoimmune myasthenia gravis (EAMG)

Nasal administration of nicotinic acetylcholine receptor (AChR) to Lewis rats prior to myasthenogenic immunization with AChR plus Freund's complete adjuvant (FCA) resulted in prevention or marked decrease of the severity of EAMG, suppression of AChR-specific B cell responses and of AChR-reactive T cell functions. To examine the involvement of immunoregulatory cytokines and the underlying mechanisms involved in tolerance induction, in situ hybridization with radiolabelled synthetic oligonucleotide probes was adopted to enumerate mononuclear cells (MNC) expressing mRNA for the proinflammatory cytokine IFN-γ, the B cell stimulating IL-4 and the immune response-down-regulating TGF-β. Popliteal and inguinal lymph nodes from EAMG rats contained elevated numbers of AChR-reactive IFN-γ, IL-4 and TGF-β mRNA-expressing cells compared with control rats receiving PBS nasally and injected with FCA only. Nasal tolerance to EAMG was accompanied by decreased numbers of AChR-reactive IFN-γ and IL-4 mRNA-expressing cells, and strong up-regulation of TGF-β mRNA-positive cells in lymphoid organs compared with non-tolerized EAMG control rats. The relative affinity of anti-AChR antibodies was lower, but muscle AChR amounts were higher in nasally tolerized rats compared with non-tolerized EAMG control rats. The results suggest that IFN-γ and IL-4 are central effector molecules in the development of EAMG, and that TGF-β plays an important role in tolerance induction to EAMG.     

Nasal tolerance in experimental autoimmune myasthenia gravis (EAMG): induction of protective tolerance in primed animals

Nasal administration of μg doses of acetylcholine receptor (AChR) is effective in preventing the development of B cell-mediated EAMG in the Lewis rat, a model for human MG. In order to investigate whether nasal administration of AChR modulates ongoing EAMG, Lewis rats were treated nasally with AChR 2 weeks after immunization with AChR and Freund's complete adjuvant. Ten-fold higher amounts of AChR given nasally (600 μg/rat) were required to ameliorate the manifestations of EAMG compared with the amounts necessary for prevention of EAMG. In lymph node cells from rats receiving 600 μg/rat of AChR, AChR-induced proliferation and interferon-gamma (IFN-γ) secretion were reduced compared with control EAMG rats receiving PBS only. The anti-AChR antibodies in rats treated nasally with 600 μg/rat of AChR had lower affinity, reduced proportion of IgG2b and reduced capacity to induce AChR degradation. Numbers of AChR-reactive IFN-γ and tumour necrosis factor-alpha (TNF-α) mRNA-expressing lymph node cells from rats treated nasally with 600 μg/rat of AChR were suppressed, while IL-4, IL-10 and transforming growth factor-beta (TGF-β) mRNA-expressing cells were not affected. Collectively, these data indicate that nasal administration of AChR in ongoing EAMG induced selective suppression of Th1 functions, i.e. IFN-γ and IgG2b production, but no influence on Th2 cell functions. The impaired Th1 functions may result in the production of less myasthenic anti-AChR antibodies and contribute to the amelioration of EAMG severity in rats treated with AChR 600 μg/rat by the nasal route.     

Animal models of myasthenia gravis

Myasthenia gravis (MG) is an antibody-mediated, autoimmune neuromuscular disease. Animal models of experimental autoimmune myasthenia gravis (EAMG) can be induced in vertebrates by immunization with Torpedo californica acetylcholine receptors (AChR) in complete Freund's adjuvant. The MHC class II genes influence the cellular and humoral immune response to AChR and are involved in the development of clinical EAMG in mice. A dominant epitope within the AChR alpha146-162 region activates MHC class II-restricted CD4 cells and is involved in the production of pathogenic anti-AChR antibodies by B cells. Neonatal or adult tolerance to this T-cell epitope could prevent EAMG. During an immune response to AChR in vivo, multiple TCR genes are used. The CD28-B7 and CD40L-CD40 interaction is required during the primary immune response to AChR. However, CTLA-4 blockade augmented T- and B-cell immune response to AChR and disease. Cytokines IFN-gamma and IL-12 upregulate, while IFN-alpha downregulates, EAMG pathogenesis. However, the Th2 cytokine IL-4 fails to play a significant role in the development of antibody-mediated EAMG. Systemic or mucosal tolerance to AChR or its dominant peptide(s) has prevented EAMG in an antigen-specific manner. Antigen-specific tolerance and downregulation of pathogenic cytokines could achieve effective therapy of EAMG and probably MG.     

Cellular mRNA expression of interferon-gamma (IFN-γ), IL-4 and IL-10 relates to resistance to experimental autoimmune myasthenia gravis (EAMG) in young Lewis rats

Age-related alterations in the immune system, including changes in lymphocyte subset composition, result in changes of cytokine patterns and might thereby influence the incidence and severity of autoimmune diseases. To investigate the age-related resistance to EAMG, an animal model for human MG, young (4-week-old) and adult (8–10-week-old) female Lewis rats were immunized with Torpedo acetylcholine receptor (AChR) and Freund's complete adjuvant (FCA). Adult Lewis rats showed severe weight loss and progressive muscular weakness after immunization, while young rats developed minor clinical signs of EAMG after a prolonged interval post-immunization. By comparison with adult rats, the young had lower AChR-specific T and B cells responses, and less muscle AChR loss. In situ hybridization performed on mononuclear cells (MNC) from lymph nodes revealed that young rats had lower levels of AChR-specific IFN-γ, IL-4 and IL-10 mRNA-expressing cells compared with adult rats. Since IFN-γ, IL-4 and IL-10 promote the development of EAMG, the low expression of these cytokines might contribute to EAMG resistance in young Lewis rats.     

Modulation of immune responses and suppression of experimental autoimmune myasthenia gravis by surgical denervation of the spleen

Critical interactions between the nervous system and the immune system during experimental autoimmune myasthenia gravis (EAMG) were examined in an animal model for human MG after immunization of adult female Lewis rats with Torpedo acetylcholine receptor (AChR) and complete Freund's adjuvant. Immunized rats depicted marked clinical severity of the disease. Using enzyme-linked immunospot (ELISPOT) assay and in situ hybridization techniques, immune responses in these animals were examined and showed elevated numbers of anti-AChR IgG secreting B cells and AChR reactive interferon (IFN)-gamma-secreting cells, enhanced mRNA expression of the proinflammatory cytokines IFN-gamma and tumour necrosis factor (TNF)-alpha as Th1 subset and the anti-inflammatory cytokines interleukin (IL)-4 and IL-10 as a Th2 subset, and transforming growth factor (TGF)-beta as a Th3 cytokine. Corticosterone and prostaglandin E(2) (PGE(2)) levels were measured by radioimmunoassay and illustrated increased production after immunization. Surgical denervation of the spleen reduced significantly the clinical severity of the disease, suppressed the numbers of IgG and IFN-gamma-secreting cells, down-regulated the mRNA expression for cytokines and reduced corticosterone and PGE(2) production. As controls, sham-operated rats were used and showed results as the EAMG non-denervated control rats. The data present herein, and for the first time, substantial effects of the nervous system on immune responses that may influence the outcome of EAMG. These effects were not dependent on cytokine inhibitory mediators such as prostaglandins or stress hormones. IL-10 and TGF-beta, the two potent immunosuppressive cytokines, were also suppressed, indicating a general suppression by splenic denervation. More investigations are initiated at our laboratories to understand the evident neural control over the immune system during challenges leading to the break of tolerance and development of autoimmunity, which may assist in innovative therapeutic approaches.     

Depletion of CD8+ T cells suppresses the development of experimental autoimmune myasthenia gravis in Lewis rats

To understand the role of CD8⁺ T cells in experimental autoimmune myasthenia gravis (EAMG), CD8⁺ T cells were depleted by injecting a monoclonal anti-rat CD8 antibody (OX8) into Lewis rats immunized with Torpedo acetylcholine receptor (AChR) in complete Freund's adjuvant (CFA). CD8-depleted EAMG rats showed strikingly less muscle weakness and lower anti-AChR IgG antibody levels compared to Hy2-15-injected control EAMG rats. Moreover, the numbers of AChR-specific IgG antibody-secreting cells, AChR-reactive interferony-γ-secreting T helper type 1-like cells and lymphocyte proliferation to AChR were lower in the CD8-depleted group than in control EAMG rats. These differences were significant among mononuclear cells from inguinal and popliteal lymph nodes, mesenteric lymph nodes and spleen, but not from thymus when examined 3, 5 and 7 weeks post-immunization. We suggest that CD8⁺ T cells are involved in the induction and persistance of EAMG by directly or indirectly affecting AChR-reactive T cells and anti-AChR IgG antibody-secreting cells.     

Dendritic cells exposed in vitro to TGF-beta1 ameliorate experimental autoimmune myasthenia gravis

Experimental autoimmune myasthenia gravis (EAMG) is an animal model for human myasthenia gravis (MG), characterized by an autoaggressive T-cell-dependent antibody-mediated immune response directed against the acetylcholine receptor (AChR) of the neuromuscular junction. Dendritic cells (DC) are unique antigen-presenting cells which control T- and B-cell functions and induce immunity or tolerance. Here, we demonstrate that DC exposed to TGF-beta1 in vitro mediate protection against EAMG. Freshly prepared DC from spleen of healthy rats were exposed to TGF-beta1 in vitro for 48 h, and administered subcutaneously to Lewis rats (2 x 10(6)DC/rat) on day 5 post immunization with AChR in Freund's complete adjuvant. Control EAMG rats were injected in parallel with untreated DC (naive DC) or PBS. Lewis rats receiving TGF-beta1-exposed DC developed very mild symptoms of EAMG without loss of body weight compared with control EAMG rats receiving naive DC or PBS. This effect of TGF-beta1-exposed DC was associated with augmented spontaneous and AChR-induced proliferation, IFN-gamma and NO production, and decreased levels of anti-AChR antibody-secreting cells. Autologous DC exposed in vitro to TGF-beta1 could represent a new opportunity for DC-based immunotherapy of antibody-mediated autoimmune diseases.     

Anti-TNF-alpha antibodies suppress the development of experimental autoimmune myasthenia gravis

To understand the role of TNF-alpha in the induction of experimental autoimmune myasthenia gravis (EAMG) and detect a possible effect of anti-TNF-alpha antibodies in the treatment of EAMG, anti-TNF-alpha antibodies were administrated intraperitoneally to Lewis rats twice per week for 5 weeks from the day of immunization with Torpedo AChR and complete Freund's adjuvant (CFA). Administration of anti-TNF-alpha antibodies resulted in lower incidence of EAMG, and in delayed onset and only mild muscle weakness compared with control EAMG rats. These mild clinical signs were accompanied by lower AChR-specific lymphocyte proliferation, down-regulated IFN-gamma and IL-10, and up-regulated TGF-beta. The lower levels of anti-AChR IgG, Ig2a and IgG2b and decreased anti-AChR IgG affinity were found in rats treated with anti-TNF-alpha antibodies. These results demonstrate that anti-TNF-alpha antibodies can suppress the induction and development of EAMG.     

Suppression of Experimental Autoimmune Myasthenia Gravis by Epitope-Specific Neonatal Tolerance to Synthetic Region α146-162 of Acetylcholine Receptor

A gene conversion event between Eb^b and Ab^b in the B6.C-H-2^bm12 (bm12) strain, which alters three amino acids in the C-terminal half of the first domain of Ab^b (Ile-67 → Phe; Arg-70 → Gln; Thr-71 → Lys) resulted in resistance to experimental autoimmune myasthenia gravis (EAMG) pathogenesis. To study the effect of bm12 mutation on the T-cell responses to epitopes of acetylcholine receptor (AChR)-α subunit, C57BL6 (B6) and bm12 mice were primed with Torpedo californica AChR, and the profiles of T-lymphocyte proliferation were determined with 18 synthetic overlapping peptides encompassing the entire extracellular portion of the AChR-α subunit. The proliferative responses of AChR-primed bm12 lymphocytes were markedly reduced to two (α146-162 and α182-198) of the three AChR peptides (α111-126, α146-162, and α182-198) that are immunodominant in B6 mice. Thus, the Ab residues encompassing the region 67-71 determine the immunogenicity of two of the AChR-α subunit T-cell epitopes. To test the involvement of AChR-α chain epitopes within peptide α146-162 in EAMG pathogenesis, B6 mice were neonatally tolerized with soluble peptide α146-162, and subsequently immunized with AChR in complete Freund's adjuvant. Neonatal tolerance to AChR or to peptide α146-162 reduced the incidence of clinical myasthenia gravis and suppressed serum anti-AChR antibodies. This indicates the involvement of T-cell epitopes within AChR-α subunit region α146-162 in EAMG pathogenesis. Neonatal tolerance to peptide α146-162 could have caused specific clonal deletion, and/or clonal anergy, and/or recruited suppressor cells to prevent clinical EAMG. Presumably, epitope(s) with AChR α146-162, in the context of Ab encompassing region 67-71, stimulate specific T helper cells which interact with specific B cells to produce pathogenic antibodies, the primary culprit causing the end plate lesion in patients with myasthenia gravis.