Characteristics of the T lymphocytes involved in experimental allergic encephalomyelitis

Both heterogeneity and restricted heterogeneity of the encephalitogenic myelin basic protein (MBP) peptide-specific T cell receptors (TCRs) were demonstrated in inbred animals depending on the strain-specific genetic characteristics, the stage of the disease, the compartment of the lymphocytes obtained and the methodology used. Nevertheless, the similar features of some MBP-specific TCRs demonstrated across species suggest that conservation of these autoantigen-specific molecules undoubtedly exists, even though the degree of this conservation is controversial. However, the unequivocal heterogeneity of the immune response directed at one of the most important myelin constituents, proteolipid lipoprotein (PLP), which occurs either as a primary or a secondary event during experimental allergic encephalomyelitis (EAE), indicates the complexity of the in vivo situation. Intramolecular and intermolecular spreading of antigen specificity during the course of the disease indicates that a TCR directed therapy may not be the choice of intervention in established disease even in individual strains of laboratory animals with restricted heterogeneity of the primary MBP-specific response. Studying the sequence of events, the recruited regulatory cells and cytokines, and the stromal factors controlling persistence or death of activated, memory cells in the tissue lesion, may reveal new therapeutic modalities with more universal applicabilities.     

Chronic relapsing experimental allergic encephalomyelitis: its value as an experimental model for multiple sclerosis

Summary Comparison of the pathohistology of chronic relapsing experimental allergic encephalomyelitis (CR-EAE) and multiple sclerosis (MS) reveals a close similarity. Thus, CR-EAE appears to be a valuable model for the study of pathogenetic factors leading to the formation of MS lesions, although the induction of the disease may be different (active sensitization with CNS antigens and adjuvant in CR-EAE versus unknown etiology in MS). CR-EAE furthermore mimicks the pathohistological patterns of other related human inflammatory demyelinating diseases (i.e., acute perivenous leukoencephalomyelitis and acute hemorrhagic leukoencephalomyelitis). The expression of an acute, predominantly inflammatory versus chronic inflammatory demyelinating disease in this model depends upon the time interval between sensitization and sampling of the animals. Recent evidence is discussed that a cooperation between cellular and humoral immune mechanisms, directed against multiple CNS antigens, is responsible for the formation of large demyelinated plaques in EAE and MS.Supported by Austrian Science Research Fund, Project S25/07     

The mechanism of inhibition of experimental allergic encephalomyelitis in the rat by monoclonal antibody against CD4

Lewis rats with actively induced or passively transferred experimental allergic encephalomyelitis (EAE) were treated with a monoclonal antibody (MAb) which binds to the CD4 antigen of rat helper/inducer T cells. Actively immunized animals treated at the first onset of clinical signs experienced only a mild form of the disease and rapidly recovered while the majority of those treated prophylactically never showed clinical signs of EAE. Passively transferred EAE was also completely inhibited with anti-CD4 MAb. In treated animals which exhibited only mild clinical signs of EAE, spinal cord and cerebellar leukocyte infiltrates were quite similar to those in untreated rats but where anti-CD4 MAb treatment completely prevented clinical EAE, histological signs were minimal or absent. Like Lewis rats which have recovered naturally from EAE, those treated with anti-CD4 MAb were both resistant to a secondary challenge with myelin basic protein and harboured potential encephalitogenic cells which were capable of transferring disease to recipient rats. Disease in these recipients was, however, of much greater severity than that experienced by animals receiving cells from naturally recovered (untreated) donors. These data demonstrate that administration of anti-CD4 MAb to rats can prevent EAE by a mechanism which does not ablate the encephalitogenic CD4+ cells or prevent the development of resistance to EAE but which may inhibit the disease by preventing the function of already activated effector cells.     

粘附分子在实验性变态反应性脑脊髓炎发生中的作用

目的 探讨粘附分子ＣＤ１１ａ,ＣＤ５４,ＣＤ６２在实验性变态反应性脑脊髓炎（ＥＡＥ）发生中的作用。方法 采用Ｗｉｓｔａｒ大鼠建立了ＥＡＥ动物模型,应用免疫荧光法检测下沉大鼠及ＥＡＥ动物周围血和脑组织中Ｔ细胞亚群及ＣＤ１１ａ,ＣＤ５４,ＣＤ６２的表达,结果 发病大鼠脑组织局灶周围大量淋巴细胞浸润,主要为ＣＤ４Ｔ细胞,发病大鼠周围血淋巴细胞上及大鼠脑组织粘附分子的表达明显升高,结论 粘附分子ＣＤ１１ａ     

调节性T细胞在实验性变态反应性脑脊髓炎和多发性硬化发病中的作用

调节性T细胞(regulatory T cells,Treg)是一类具有免疫调节功能的T细胞哑群.近年来,Treg细胞在实验性变态反应性脑脊髓炎(experimental allergical encephalomyelitis,EAE)、多发性硬化(multiple sclerosis,MS)发病中的作用越来越受到关注,小鼠Treg细胞缺失可导致特异性自身免疫性疾病,增加Treg细胞的功能可以减轻或抑制EAE.最近的研究结果表明,MS本身也伴随着成熟Treg细胞的受损或功能障碍.     

Direct demonstration of the infiltration of murine central nervous system by Pgp-1/CD44 CD45RB CD4 T cells that induce experimental allergic encephalomyelitis

In experimental allergic encephalomyelitis (EAE), autoimmune T cells infiltrate the central nervous system (CNS) and initiate demyelinating pathology. We have used flow cytometry to directly analyse the migration to the CNS of MBP-reactive CD4⁺ T cells labelled with a lipophilic fluorescent dye (PKH2), in SJL/J mice with passively transferred EAE. Labelled cells constituted about 45% of the CNS CD4⁺ population at the time of EAE onset. Almost all (>90%) of the PKH2-labelled CD4⁺ T cells from EAE CNS were blasts and were α/β T cell receptor (TCR)⁺, CD44(Pgp-1)^high, and the majority were CD45RB^low. By contrast, most PKH2-labelled CD4⁺ T cells in lymph nodes, although CD44^high, were CD45RB^high cells. The cells that were transferred to induce EAE were essentially similar to antigen-primed lymph node cell populations, containing less than 15% CD44^high cells, and most of them were CD45RB^high. The CD44^high CD45RB^low phenotype is characteristic of memory/effector T cells that have been activated by antigen recognition. The difference in CD45RB expression between CNS and LN could therefore reflect differential exposure and/or response to antigen. Consistent with this, PKH2-labelled CD4⁺ cells isolated from the CNS were responsive to MBP in vitro, whereas PKH2⁺ CD4⁺ cells from lymph nodes showed almost undetectable responses. In control experiments in which ovalbumin (OVA)-reactive T cells were transferred, a small number of fluorescent-labelled CD4⁺ T cells were also detected in CNS, but there were very few blasts, and these remained CD45RB^high. These results argue for induction of the memory/effector phenotype of CD4⁺ cells, their selective retention in the CNS, as a consequence of antigen recognition.     

Ia-expressing microglial cells in experimental allergic encephalomyelitis in rats

Summary Monoclonal antibodies (MRC OX-6 and OX-17) recognized three types of cells expressing Ia antigen during the course of acute experimental allergic encephalomyelitis (EAE) in rats. In earlier stages of the disease, in animals with or without paralysis, Ia antigens were mostly localized to subarachnoidal and perivascular lymphocytic and histiocytic cell infiltrates, possibly serving as antigen-presenting cells. On the other hand, in convalescent rats, Ia antigens were expressed in a large number of cells with dendritic processes heavily populating the spinal gray matter. The appearance of these Ia-expressing cells in the convalescent stage coincided with the development of degenerating axon terminals in the spinal gray matter. These Ia-expressing cells possessed morphological features characteristic of microglia and were positive for ML-1 lectin but did not express glial fibrillary acidic protein. Immune electron microscopy disclosed the presence of Ia reaction products in the Golgi apparatus, endoplasmic reticulum and plasma membrane of these cells with dendritic processes, indicating active synthesis of Ia molecules in microglia. In addition, Ia antigens were localized to the cells with ultrastructural features of macrophages. Thus, Ia-expressing cells in EAE seems to play dual roles: the induction of immunological reactions during earlier stages and the participation in reparative processes during convalescence.Supported by Grants-in-aid from the Ministry of Health and Welfare for Intractable Neuroimmunological Diseases and from the Ministry of Education, Science and Culture (Project 61570380 to HK)     

Studies of experimental allergic encephalomyelitis in old mice

In old BALB/c mice susceptibility to experimental allergic encephalomyelitis (EAE) with bovine proteolipid apoprotein (PLP) is reduced significantly. Eleven of 21 8-week BALB/c mice developed clinical signs of EAE following injection of PLP but only two of 18 12-month BALB/c mice and one of 19 24-month BALB/c mice showed clinical signs of EAE. Susceptibility to EAE induced by either PLP or bovine myelin basic protein (MBP) also was reduced in old SJL mice. However, the aging process had no effect on the clinical signs of EAE in both strains, if EAE appeared. Some old BALB/c mice developed histologic EAE with significant demyelination without clinical signs. Lymphocyte proliferative response to mitogens and antigens, and interleukin-2 (IL-2) production, also were depressed in the aged mice (24-month BALB/c and 18-month SJL) probably due to the functional defect of T cells, since the function of macrophages as antigen-presenting cells was not affected in the old mice. PLP-sensitized spleen cells (SPC) from 8-week mice were able to adoptively transfer EAE to young and aged recipients. PLP-sensitized T cells from 8-week mice, reconstituted with young or old monocytes, also were able to transfer EAE into young mice. In contrast, spleen cells from aged mice did not induce EAE, so the reduction of EAE susceptibility was mainly explained by the failure of T cell activity. This T cell defect was not restored by exogenous IL-2.     

Blood levels of kinins in experimental allergic encephalomyelitis

The pathology of acute experimental allergic encephalomyelitis is characterized by perivascular cellular infiltrates in the central nervous system. Our hypothesis is that this immuno-pharmacological process can activate the circulating and tissular kallikrein-kinin systems. We studied 21 New Zealand rabbits inoculated with a homogenate of guinea-pig spinal cord in complete Freund's adjuvant. Each animal underwent radioimmunoassay for arterial blood bradykinin, des-Arg9-bradykinin and des-Phe8-des-Arg9-bradykinin during the acute or subacute clinical phase of encephalomyelitis. Immediately after blood sampling, all animals had their complete central nervous system dissected out and prepared for staining and histological study. The number of hematoxylin-eosin-stained perivascular cellular infiltrates was counted at eight levels of the central nervous system, from the hypothalamic to sacral spinal segments. We demonstrated a positive significant (P less than or equal to 0.02) correlation (r = 0.55) between the number of perivascular cellular infiltrates and blood level of the biologically active kinin bradykinin.     

About demyelinating properties of humoral antibodies in experimental allergic encephalomyelitis

Summary In order to elucidate the role of humoral antibodies in the pathogenesis of myelin lesions in experimental allergic encephalomyelitis (EAE) a combined in vivo and in vitro study was done using rabbits immunized with the purified A₁ basic protein. Rabbits injected with whole white matter were used for comparison. Demyelinating activity appeared in the rabbit sera 5 days after injection, as tested in myelinated organotypic tissue cultures. In spite of this no lesions of the myelin preceded the appearance of inflammatory cells in the living animals. In the spinal cord changes in vascular permeability, as revealed by leakage of Evans blue-albumin complex, appeared at the same times as the cells. In contrast to in vitro, the mere presence of circulating antibodies in vivo does not appear to be enough to cause structural changes of the myelin. Possible reasons for this discrepancy are discussed; it is emphasized that the inflammatory changes develope first in areas where the so-called blood-brain barrier to diffusion of proteins is lacking.     

Dendritic cells in experimental allergic encephalomyelitis and multiple sclerosis

The mechanisms by which autoimmune diseases are triggered and by which the activation of autoreactive T cells is initiated and maintained are not yet fully understood. As the most potent antigen presenting cells (APC), and also being responsible for antigen transport as well as primary sensitisation of T cells, dendritic cells (DC) are capable of breaking the state of self-ignorance and inducing aggressive autoreactive T cells. In the development of autoimmune diseases, different types of DC exhibit distinct properties for inducing Th1/Th2 cell responses. Appropriate cytokines can convert immunogenic DC to tolerogenic DC. Utilizing the possibility to promote the tolerogenic effects of DC, a new therapeutic tool might soon become available to treat multiple sclerosis and other autoimmune diseases.     

Abrogation of induced resistance to experimental allergic encephalomyelitis in guinea pigs by host-versus-graft reaction

Experimental allergic encephalomyelitis (EAE) effector cells known to exist in guinea pigs with myelin basic protein-incomplete Freund's adjuvant (MBP-IFA)-induced resistance to EAE could be activated in vivo by means of allogeneic confrontation (local host-versus-graft reaction (HVGR)). The abrogation of the resistance was observed only when HVGR was combined with encephalitogenic challenge (myelin basic protein-complete Freund's adjuvant (MBP-CFA)) in a certain order and at certain time intervals. The injection of 20 x 10(7) gamma-irradiated allogeneic lymphoid cells 7 or 4 days prior to or along with MBP-CFA treatment resulted in development of EAE with delayed onset and protracted course. The effect was most prominent when HVGR was induced on day -4. Histological examination revealed inflammatory lymphoid cell infiltrations in spinal cord. Serum level of total and anaphylactic anti-MBP antibodies correlated with the clinical picture.     

Enhancing effects of irrelevant lymphocytes on adoptive transferred experimental allergic encephalomyelitis

To help understand effector mechanisms in experimental allergic encephalomyelitis (EAE) we examined the effects of adding ‘irrelevant’ lymphocytes from non-EAE donors to major basic protein (MBP)-reactive lymphocytes in the adoptive transfer of EAE (Tr-EAE). The intravenous injection of tentanus toxoid-reactive lymphocytes (TT-cells) and phytohemagglutinin-stimulated lymphocytes on the same day or 2 days after intra-arterial injection of MBP-reactive lymphocytes enhanced the clinical and pathological expression of Tr-EAE. In lymphocyte trafficking studies there was significant accumulation of these injected TT-cells in the central nervous system during enhanced transfer of EAE. W3/25-positive cells were much more predominant in lesion of central nervous system when reinjected with TT cells along with MBP cells compared with lesions of rats injected with MBP cells alone. These findings suggest possible participation of lymphocytes other than MBP-reactive cells in the expression of EAE and provide a useful model to further explore effector mechanism in the future.     

Restraint stress suppresses experimental allergic encephalomyelitis in Lewis rats

We studied the effect of restraint stress on experimental allergic encephalomyelitis (EAE), a model for the human disease multiple sclerosis (MS), in Lewis rats. Rats were subjected to 12 h restraint stress for 3 consecutive nights from the first (day 1) or the eighth day (day 8) after sensitization with the antigen (guinea-pig spinal cord). All controlled rats exhibited clinical and histologie signs of EAE. The mean ± SD of incubation time, clinical score (0–4) and histologic score (0–3) for this group were 12.8 ± 1.0 days, 2.7 ± 0.6, and 2.3 ± 0.7, respectively. Restraint stress from day 8 significantly suppressed EAE: the mean ± SD of incubation time, clinical score, and histologic score for this group were 17.2 ± 2.2 days (p < 0.001), 1.8 ± 1.3 (p < 0.05), and 1.5 ± 0.9 (p < 0.02), respectively. Restraint stress from day 1 did not modify EAE. The findings suggest that stressful factors may exert an influence on the clinical course of MS.     

实验性变应性猴脑脊髓炎的超微结构改变

目的探讨自身免疫性中枢神经系统（ＣＮＳ）脱髓鞘的病理特点和发病过程。方法建立猴实验性变态反应性脑脊髓炎（ＥＡＥ）的模型，并从病情不同阶段进行病理取材和电镜观察。结果（１）ＥＡＥ脱髓鞘最早的靶是少突胶质细胞（ＯＤＣ），而不是髓鞘本身；（２）无论急性期还是慢性期，脱髓鞘病灶内只有极少的炎细胞浸入；（３）急性期髓鞘改变轻微，以变性为主，ＯＤＣ肿胀显著，轴突相对完整。远离髓鞘变性区有大量炎细胞浸入；（４）慢性期病变区髓鞘脱失明显，ＯＤＣ严重变性或部分丢失，继发性轴突变性，边缘可见少量薄的髓鞘再生，血脑屏障破坏。结论ＥＡＥ的ＣＮＳ脱髓鞘过程首先累及ＯＤＣ。     

实验性变态反应性脑脊髓炎大鼠星形胶质细胞的变化

目的观察实验性变态反应性脑脊髓炎(EAE)大鼠脊髓中星形胶质细胞的变化,探讨EAE大鼠的发病相关生物学机制。方法采用免疫组化法,对豚鼠全脊髓匀浆诱导的Wistar大鼠EAE的过程中,脊髓内星形胶质细胞变化情况进行研究。结果EAE大鼠症状高峰期时星形胶质细胞开始激活,恢复期时激活达到高峰,而且活化的星形胶质细胞未见表达主要组织相容性抗原(MHC)。结论活化的星形胶质细胞可能与EAE大鼠的恢复有关。     

Pregnancy and the susceptibility of Lewis rats to experimental allergic encephalomyelitis

Pregnant Lewis rats challenged with encephalitogen during the second or third week of gestation were afforded a high level of protection against experimental allergic encephalomyelitis, whilst females sensitised during the first week of pregnancy enjoyed only limited protection from clinical signs of disease. When rechallenged with encephalitogen, females which had been sensitised during pregnancy were marginally more susceptible to reinduction of clinical signs of disease than their virgin counterparts. Mothers inoculated during the first week of gestation were the only group to produce abnormal young.     

Sympathectomy augments adoptively transferred experimental allergic encephalomyelitis

Adoptively transferred experimental allergic encephalomyelitis (EAE) was significantly augmented in Lewis rats with ablated sympathetic nervous system. Sympathectomy was obtained by treatment of newborn rats with 6-hydroxydopamine. Sham-injected rats were used as a control. EAE was elicited in 7-8-week-old donor Lewis rats by immunization with a suspension of guinea pig (GP) brain and spinal cord in complete Freund's adjuvant. Successful transfer of EAE was accomplished with 50 x 10(6) lymph node cells (LNC)/rat, incubated for 72 h with GP myelin basic protein. LNC were obtained from draining lymph nodes, 9 days after immunization for EAE. The severity of passively transferred EAE was significantly augmented when donor LNC obtained from normal Lewis rats immunized for EAE were injected into sympathectomized rats as compared to sham-injected rats. When LNC were obtained from sympathectomized or sham-injected donors, the disease was significantly more severe in recipients of cells from sympathectomized animals. The severity of histological lesions in the brain and spinal cord was greater in rats with passively transferred EAE which received LNC from sympathectomized donors.     

Immunologic differences in murine glial cells and their association with susceptibility to experimental allergic encephalomyelitis

We tested the hypothesis that glial cells from mice resistant or susceptible to the autoimmune disease experimental allergic encephalomyelitis (EAE) may differ in their abilities either to express Ia antigens and/or stimulate anti-class II (Ia)-specific T-cells. Ia antigens were induced on glial cells from EAE-susceptible (SJL/J) and -resistant (B10.S and DBA/2) strains of mice by culture with lymphokines from activated T-cells (2 degrees SN). Ia antigen expression was quantified with an enzyme-linked immunosorbent assay (ELISA) in which glia were exposed to monoclonal anti-Ia antibodies and alkaline phosphatase-labeled anti-mouse Ig antibodies. The ability of glial cells to stimulate anti-Ia T-cells was quantified by culturing irradiated glial cells with anti-Ia-specific T-cell lines and measuring the amounts of [3H]thymidine incorporated by these lines. Glial cells from all strains of mice could be induced to express Ia antigens and upon exposure to high concentrations of lymphokines, amounts of expressed Ia antigen were equivalent. However, at limiting lymphokine concentrations, glia from the EAE-resistant strain B10.S expressed greater amounts of Ia antigen than did glia from SJL/J mice (p less than 0.05), suggesting that B10.S glia were more sensitive to the Ia-inducing effects of T cell lymphokines. In contrast to the above results, glia from EAE-susceptible SJL mice consistently demonstrated an increased ability to induce T-cell proliferation in lines specific for Ias antigen, compared to glia from EAE-resistant mice, even those of the same Ia haplotype (i.e. B10.S). Spleen cells from resistant strains had equivalent and frequently greater ability to induce anti-Ia-specific T-cell proliferation than did SJL spleen cells. These data suggest (a) that there are differences in the sensitivity of glia from different strains of mice to the Ia antigen-inducing effects of T-cell lymphokines, (b) that expression of Ia antigen does not necessarily correlate with the ability to stimulate Ia-specific T-cells, (c) that there are organ-specific differences in the ability to stimulate Ia antigen-specific T-cells, and (d) that an additional variable involved in determining resistance or susceptibility to an organ-specific autoimmune disease may be the ability of the target organ to stimulate anti-Ia-specific T-cells.     

实验性变态反应性脑脊髓炎大鼠胸腺形态学变化研究

目的研究实验性变态反应性脑脊髓炎(EAE)大鼠发病后不同时期胸腺形态学变化。方法取发病后3天、5天及恢复期EAE大鼠胸腺,测量各组大鼠体重、胸腺重量,计算胸腺指数,并于光镜、电镜下观察胸腺细胞变化情况。结果光镜显示发病3天胸腺显著萎缩,皮质变薄,淋巴细胞数减少,细胞松散。凋亡细胞数增多,核染色质浓缩,核固缩;发病5天组较3天组细胞数量有所恢复,低于恢复期组。恢复期组细胞数明显增多,结构较为紧密。电镜显示3天组与5天组淋巴细胞较恢复期组减少,可见多数凋亡细胞。3天组、5天组胸腺重量与恢复期组相比有显著差异(P<0.05)。胸腺指数显示3天组胸腺指数较其他组明显下降(P<0.05),其余组两胸腺指数相比无统计学意义(P>0.05)。结论发病的EAE大鼠胸腺呈现先萎缩、后恢复的过程,细胞减少以发病后3天最明显,可见多数凋亡细胞,恢复期细胞数量增多,结构较为紧密。表明胸腺随疾病的发生呈动态变化,具有可恢复性。