Inhibition of experimental autoimmune encephalomyelitis in Lewis rats by nasal administration of encephalitogenic MBP peptides: synergistic effects of MBP 68-86 and 87-99

Induction of mucosal tolerance by inhalation of soluble peptides with defined T cell epitopes is receiving much attention as a means of specifically down-regulating pathogenic T cell reactivities in autoimmune and allergic disorders. Experimental autoimmune encephalomyelitis (EAE) induced in the Lewis rat by immunization with myelin basic protein (MBP) and Freund's adjuvant (CFA) is mediated by CD4+ T cells specific for the MBP amino acid sequences 68-86 and 87-99. To further define the principles of nasal tolerance induction, we generated three different MBP peptides (MBP 68-86, 87-99 and the non- encephalitogenic peptide 110-128), and evaluated whether their nasal administration on day -11, -10, -9, -8 and -7 prior to immunization with guinea pig MBP (gp-MBP) + CFA confers protection to Lewis rat EAE. Protection was achieved with the encephalitogenic peptides MBP 68-86 and 87-99, MBP 68-86 being more potent, but not with MBP 110-128. Neither MBP 68-86 nor 87-99 at doses used conferred complete protection to gp-MBP-induced EAE. In contrast, nasal administration of a mixture of MBP 68-86 and 87-99 completely blocked gp-MBP-induced EAE even at lower dosage compared to that being used for individual peptides. Rats tolerized with MBP 68-86 + 87-99 nasally showed decreased T cell responses to MBP reflected by lymphocyte proliferation and IFN-gamma ELISPOT assays. Rats tolerized with MBP 68-86 + 87-99 also had abrogated MBP-reactive IFN-gamma and tumor necrosis factor-alpha mRNA expression in lymph node cells compared to rats receiving MBP 110-128 nasally, while similar low levels of MBP-reactive transforming growth factor-beta and IL-4 mRNA expressing cells were observed in the two groups. Nasal administration of MBP 68-86 + 87-99 only slightly inhibited guinea pig spinal cord homogenate-induced EAE, and passive transfer of spleen mononuclear cells from MBP 68-86 + 87-99-tolerized rats did not protect naive rats from EAE. Finally, we show that nasal administration of MBP 68-86 + 87-99 can reverse ongoing EAE induced with gp-MBP, although higher doses are required compared to the dosage needed for prevention. In conclusion, nasal administration of encephalitogenic MBP peptides can induce antigen-specific T cell tolerance and confer incomplete protection to gp-MBP-induced EAE, and MBP 68-86 and 87-99 have synergistic effects. Non-regulatory mechanisms are proposed to be responsible for tolerance development after nasal peptide administration.      

Conserved T cell receptor V gene usage by uveitogenic T cells

Retinal S-antigen is widely used to study the LEW rat model of experimental autoimmune uveoretinitis (EAU). In this report, we have examined the T cell receptor V gene usage of several T cell lines recognizing either pathogenic or nonpathogenic sites on S-antigen to determine whether the V alpha 510 and V beta 510 rat homologues of the murine V alpha 2 and V beta 8 families, respectively, are used by uveitogenic T cells. Using cDNA probes for a LEW rat T cell receptor specific for the encephalitogenic determinant of myelin basic protein, we have found that in the retinal S-antigen/EAU model for autoimmune disease, pathogenicity correlates with usage of those rat V genes. Thus, all of the pathogenic lines were found to express T cell receptors of the V beta 510 and V alpha 510 families; conversely, V beta 510 usage was not detected in any of the nonpathogenic lines. Usage of these V regions has been associated with pathogenicity in the murine and rat models of experimental autoimmune encephalomyelitis, and now with S-antigen-induced EAU.     

Characterization of brain-isolated rat encephalitogenic T cell lines

In the present study, we have isolated and characterized five myelin basic protein (MBP)-reactive T cell lines directly from the brains of Lewis rats during the early paralytic phase of experimental autoimmune encephalomyelitis (EAE). Each T cell line responded to the dominant encephalitogenic epitope spanning residues 68–88, and did not react against the conserved encephalitogenic epitope [MBP(87–99)] or the nonencephalitogenic MBP epitope [MBP(50–69)]. We determined the T cell receptor (TcR) β chain usage by polymerase chain reaction, DNA sequencing analysis and by generation of MBP-reactive hybridomas from one of the T cell lines (BT74). The results revealed that brain-infiltrating, MBP-reactive T cells freshly isolated early in the course of the disease exhibit TcR diversity.     

经鼻黏膜给予MBP68-86和87-99协同免疫预防Lewis大鼠EAE的实验研究

目的探讨鼻黏膜给予MBP68-86和87-99协同免疫预防Lewis大鼠实验性自身免疫性脑脊髓炎(EAE)的作用。方法合成3条不同的碱性髓鞘蛋白(MBP)多肽(MBP68-86、87-99和非致脑炎性肽段110-128),在用豚鼠MBP(gp-MBP)加弗氏完全佐剂免疫Lewis大鼠前的11、10、9、8和7d,经鼻黏膜分别给予MBP多肽,观察其对EAE的保护作用。结果致脑炎性肽段MBP68-86和87-99都有保护作用,其中MBP68-86的保护作用更强;而MBP110-128没有保护作用。鼻黏膜给予MBP68-86 87-99的混合物,在相对低的剂量可完全阻断gp-MBP引发的EAE。淋巴细胞增殖实验和IFN-γELISPOT检测显示,与鼻黏膜给予大鼠MBP110-128组相比,鼻黏膜给予大鼠MBP68-86 87-99可降低T细胞对于MBP的反应性,淋巴结单核细胞中表达IFN-γ和TNF-αmRNA的细胞数减少,而两组表达TGF-β及IL-4mRNA的淋巴细胞数都低。结论鼻黏膜给予致脑炎性MBP多肽能够导致抗原特异性T细胞耐受,对gp-MBP引发的EAE提供不完全的保护,MBP68-86和MBP87-99具有协同作用。鼻黏膜给予多肽引发的免疫耐受与非调节机制有关。     

The myelin basic protein-specific T cell repertoire in (transgenic) Lewis rat/SCID mouse chimeras: preferential Vβ8.2 T cell receptor usage depends on an intact Lewis thymic microenvironment

In the Lewis rat, myelin basic protein (MBP)-specific, encephalitogenic T cells preferentially recognize sequence 68–88, and use the Vβ8.2 gene to encode their T cell receptors. To analyze the structural prerequisites for the development of the MBP-specific T cell repertoire, we reconstituted severe-combined immunodeficient (SCID) mice with fetal (embryonic day 15–16) Lewis rat lymphoid tissue, and then isolated MBP-specific T cell lines from the adult chimeras after immunization. Two types of chimera were constructed: SCID mice reconstituted with rat fetal liver cells only, allowing T cell maturation within a chimeric SCID thymus consisting of mouse thymic epithelium and rat interdigitating dendritic cells, and SCID mice reconstituted with rat fetal liver cells and rat fetal thymus grafts, allowing T cell maturation within the chimeric SCID and the intact Lewis rat thymic microenvironment. Without exception, the T cell lines isolated from MBP-immunized SCID chimeras were restricted by MHC class II of the Lewis rat (RT1.B¹), and none by I-A^d of the SCID mouse. Most of the T cell lines recognized the immunodominant MBP epitope 68–88. In striking contrast to intact Lewis rats, in SCID mice reconstituted by rat fetal liver only, MBP-specific T cell clones used a seemingly random repertoire of Vβ genes without a bias for Vβ8.2. In chimeras containing fetal Lewis liver plus fetal thymus grafted under the kidney capsule, however, dominant utilization of Vβ8.2 was restored. The migration of liver-derived stem cells through rat thymus grafts was documented by combining fetal tissues from wild-type and transgenic Lewis rats. The results confirm that the recognition of the immunodominant epitope 68–88 by MBP-specific encephalitogenic T cells is a genetically determined feature of the Lewis rat T cell repertoire. They further suggest that the formation of the repertoire requires T cell differentiation in a syngeneic thymic microenvironment.     

T cell receptor beta chain usage in myelin basic protein-specific rat T lymphocytes

Myelin basic protein (MBP)-specific T cell lines and clones have been established from rats of the major histocompatibility complex (MHC)-compatible Lewis and BS strains. All lines and clones are MHC class II restricted and share the CD4+ phenotype. The cells proliferate specifically in response to either a peptide representing amino acids #68-88 of guinea pig MBP, to residues #47-67 or to an unidentified myelin antigen which is distinct from MBP. All lines and clones specific for MBP express the same T cell receptor (TcR) variable (V) beta chain element, which is homologous to the mouse V beta 8.2 gene segment. Three lines/clones with the same antigen fine specificity have identical V beta D beta J beta junctions on the protein level, a region which represents part of the potential antigen-binding portion of the TcR; two of the lines express members of the V alpha 2 family. These results suggest biased usage of TcR V beta elements in rat T cells specific for MBP. Our findings broaden the basis for a rational therapeutic strategy to specifically intervene in the rodent model system of experimental allergic encephalomyelitis.     

Protection from experimental allergic encephalomyelitis by application of a bacterial superantigen.

Certain bacterial and viral T cell stimulating proteins ('superantigens') are known to be very potent activators of T cells with certain V beta receptors. When applied in vivo these molecules induce anergy in those T cells responding to them. In this study we have investigated the influence of staphylococcal enterotoxins (SE) on myelin basic protein (MBP)-specific T cells in Lewis rats. As MBP-specific T cells in rats belong exclusively to the V beta 8.2+ CD4+ subset, the induction of experimental allergic encephalomyelitis (EAE) allows for an estimation of the functional state of the respective V beta-bearing T cells after enterotoxin-induced activation. In vitro, various MBP-specific T cell lines showed a strong selective proliferative response to staphylococcal enterotoxin E (SEE) but not to other SE. The in vitro activation by SEE induced encephalitogenic potential in these cells. After application of SEE to Lewis rats the susceptibility to induction of EAE was completely abrogated. Such SEE-treated and MBP-challenged rats did not exhibit any signs of disease and their T cells did not respond to MBP in proliferation tests. This abrogation of EAE was only found with a superantigen capable of interacting specifically with V beta 8.2+ T cells. Superantigen-mediated induction of unresponsiveness may have relevance for the analysis of pathogenetic mechanisms and for therapeutic considerations in certain T cell-mediated autoimmune diseases.     

Human CD8+ T cell clone regulates autologous CD4+ myelin basic protein specific T cells.

Normal human CD8+ T cell clones were co-isolated from the same culture wells as CD4+ T effector cell clones specific for myelin basic protein (MBP). Microcultures from which the CD8+ clones were isolated initially proliferated weakly to whole MBP and to an MBP peptide spanning residues 90-170. This pattern of response was similar to strongly proliferating wells that yielded CD4+ T cell clones specific for the 90-170 peptide. After repeated stimulation, however, no response to MBP or MBP 90-170 was detected, even though the number of cells increased after stimulation. Phenotyping and TCR analyses revealed the presence of two CD8+, CD4-, IL-2R+ T cell isolates that expressed a single V beta gene (V beta 17) that differed from the CD4+ isolates that uniformly expressed V beta 14. One of these CD8+ clones (C9) inhibited the antigen-driven proliferation of an autologous MBP 90-170 reactive clone but not an autologous clone specific for Herpes simplex virus (HSV), without affecting MHC non-restricted mitogen responses of the same clones. Moreover, C9 did not inhibit heterologous CD4+ T cell clones specific for MBP 1-38 or 90-170. A culture supernatant of the CD8+ clone showed the same pattern but lower levels of inhibition. C9 had mild cytolytic activity when incubated at high ratios with an autologous MBP-specific CD4+ clone. Lysis was blocked completely by anti-MHC class I antibodies, but not by anti-MHC II antibodies.(ABSTRACT TRUNCATED AT 250 WORDS)     

Tolerance induction by acylated peptides: effect on encephalitogenic T cell lines

We reported previously that acylation of an encephalitogenic peptide of myelin basic protein (MBP68-86) by attachment of palmitoyl chloride (PAL68-86) converted this peptide into a powerful tolerogen for EAE in the Lewis rat. In this study we show that T cell lines derived from a PAL68-86-protected rat proliferated poorly to MBP68-86 in vitro, even after repeated passages in this peptide and IL-2. Conversely, T cell lines derived from untreated rats that were challenged with MBP68-86 or PAL68-86 in CFA responded vigorously to MBP68-86 when propagated for many passages in this peptide but became gradually unresponsive after being propagated in the presence of PAL68-86. The modulation of the T cell lines by PAL68-86 in vitro was reflected by a significant reduction in their ability to transfer EAE to recipients. A high percentage of cells stained with an anti-Vbeta8.2 antibody, regardless of whether they were propagated in the presence of unmodified or acylated peptide. The results are consistent with the notion that tolerance induced by PAL68-86 operates by functional inactivation and provide the basis for the use of acylated peptides in the antigen-specific treatment of autoimmune diseases.     

Heterogeneity of rat encephalitogenic T cells elicited by variants of the myelin basic protein (68–86) peptide

By immunizing Lewis rats with myelin basic protein (MBP) peptide variants derived from the major encephalitogenic epitope of guinea pig (MBP(68–88) and then isolating encephalitogenic T cells from these animals, we demonstrated that the variant peptides do not elicit the same encephalitogenic T cell subsets as those induced by the wild-type peptide or by intact MBP. Rather, the pathogenic T cells differed in clonal composition as reflected by their heterogeneous responses to a panel of variant peptides and by their T cell receptor usage. Thus, molecules mimicking the MBP(68–88) autoantigen can elicit pathogenic T cell subsets without necessarily cross-reacting with T cells specific for the original autoantigen. This suggests that a more clonally diverse group of pathogenic T cells might be involved in EAE than has been apparent from studies with intact MBP or its unaltered peptides.     

Encephalitogenic,myelin basic protein-specific T cells from naive rat thymus: preferential use of the T cell receptor gene Vβ8.2 and expression of the CD4− CD8− phenotype

Using a primary limiting dilution approach to generate T cell lines, we compared myelin basic protein (MBP)-specific T cell clones from naive unprimed Lewis rat thymuses with the corresponding T cell repertoire of primed rats. We found that in the naive thymus repertoire MBP-specific, encephalitogenic T cell clones preferentially use T cell receptor Vβ8.2 genes, along with CDR3 sequences typical for the primed Lewis anti-MBP response. In contrast to T cells from primed immune organs, which all display the CD4⁺ CD8^? phenotype, the majority of naive thymus-derived T cell clones expressed reduced levels of the CD4 co-receptor. Some clones were completely CD4^?CD8^?, while others included CD4^? CD8^? subpopulations along with CD4⁺CD8^? T cells. In the one mixed population examined in detail, the CD4^?CD8^? and CD4⁺CD8^? T cell subpopulations used a T cell receptor with identical β chain sequence. The data suggest that in the Lewis rat the biased T cell receptor gene usage by encephalitogenic T cells is a property of the natural thymic T cell repertoire, possibly as a consequence of positive selection. The unusually low expression of CD4 in the major histocompatibility complex class II-restricted autoreactive T cells could be related to their escape from negative selection within the thymus.     

Predominant usage of V beta 8.3 T cell receptor in a T cell line that induces experimental autoimmune uveoretinitis (EAU).

Experimental autoimmune uveoretinitis (EAU) is a T cell-mediated autoimmune disease induced in animals by immunization with retinal proteins (or synthetic fragments derived from them) in adjuvant, and it is considered a model of human autoimmune diseases of the eye. To study the T cell clonotypes that may be involved in EAU, we analyzed the T cell repertoire of three related T cell lines: the pathogenic line LR16, specific to the major uveitogenic epitope of IRBP; its pathogenic subline J; and its nonpathogenic subline A. We examined the expression of the genes coding for the variable regions of the 20 known Lewis rat T cell antigen receptor (TCR) V beta families. The nonpathogenic subline was found to contain mostly T cells expressing V beta 5, V beta 8.2, and V beta 19 while the pathogenic subline consisted mainly of cells expressing V beta 8.3 TCRs. Genomic Southern blot analysis of DNA from the pathogenic subline showed that V beta 8.3-expressing T cells were the dominant clonotype, and DNA sequence analyses of V beta 8.3 cDNAs revealed that two V beta 8.3 TCRs were expressed in the pathogenic subline. One of the V beta 8.3 cDNAs encoded a variable region gene segment identical to previously reported rat V beta 8.3 TCR while the other differed by two amino acids in the second complementarity determining region (CDR2). Taken together with previous data showing overrepresentation of V beta 8-expression in T cell lines that induce EAU, but not in nonuveitogenic T cell lines, our results suggest that V beta 8.3-expressing T cells represent a pathogenic clonotype in IRBP-induced EAU.     

Delineation of tissue damage mechanisms in experimental autoimmune encephalomyelitis (EAE). I. Cell detachment and lysis induced by encephalitogenic CD4+ T lymphocytes.

Myelin basic protein (MBP) reactive CD4+ T lymphocytes, capable of inducing experimental autoimmune encephalomyelitis (EAE), were examined for their ability to damage target cells of central nervous system (CNS) origin. Damage was assessed by monitoring detachment of adherent astrocytes from substratum and astrocyte lysis. MBP-specific, but non-encephalitogenic CD4+ T cells mediated astrocyte detachment but not lysis. However, encephalitogenic CD4+ T cell lines were more efficient in causing astrocyte detachment and could also cause astrocyte lysis. The detachment and lytic activities of the MBP-reactive T cell lines tested were often independent of the presence of specific antigen, and were not restricted to syngeneic major histocompatibility (MHC) antigens. MBP often augmented the detaching and, if lytic, lytic activities of these T cells. The encephalitogenic CD4+ T cells also detached and lysed allogeneic 'bystander' fibroblasts in the presence of unlabelled syngeneic astrocytes, suggesting the involvement of a soluble mediator(s). Although MBP is essential for the initiation of EAE, the presence of MBP on cells of CNS origin, such as astrocytes and oligodendrocytes, does not appear to be necessary for their damage by MBP-specific CD4+ T cells. Immune CD4+ T cells, which penetrate the CNS, may disorganize brain tissue structure by lysing astrocytes directly and by damaging other brain cells indirectly by soluble mediators. Thus cellular detachment, in addition to cell lysis, mediated by MBP-specific CD4+ cells may contribute to EAE pathogenesis.     

Restricted TCR Valpha gene rearrangements in T cells recognizing an immunodominant peptide of myelin basic protein in DR2 patients with multiple sclerosis

T cell responses to myelin basic protein (MBP) are thought to play an important role in the pathogenesis of multiple sclerosis (MS). The response to the 83-99 region of MBP represents a dominant response to MBP in patients with MS and is associated with HLA-DR2 that is linked with susceptibility to MS. Although T cell clones reactive to various regions of MBP have been found to exhibit heterogeneous TCR Vbeta gene usage in patients with MS, it is unclear whether T cell clones uniformly recognizing the 83-99 peptide of MBP in the context of the same DR molecule would have restricted TCR V gene rearrangements and recognition motifs. In this study, a panel of DR2- or DR4-restricted T cell clones specific for the MBP83-99 peptide were derived from 11 patients with MS and examined for TCR V gene usage by PCR and the recognition motifs using analog peptides. Our study revealed that despite a few T cell clone pairs having similar recognition motifs and shared sequence homology in the CDR3, the overall recognition motifs of MBP83-99-specific T cells were considerably diverse. Interestingly, the DR2-restricted T cell clones displayed a biased V gene usage for Valpha3 and Valpha8, while Vbeta gene rearrangements were highly heterogeneous. This study provided experimental evidence suggesting a limited heterogeneity in TCR Valpha gene rearrangements of MBP-reactive T cells in DR2 patients with MS.      

Successful prevention and treatment of autoimmune encephalomyelitis by short-term administration of anti-T-cell receptor alpha beta antibody.

To identify an effective immunotherapy for T-cell-mediated autoimmune diseases, prevention and treatment of experimental autoimmune encephalomyelitis (EAE) induced in Lewis rats was attempted by administering a monoclonal antibody (mAb), R73, which is specific for rat T-cell receptor (TcR) alpha beta. Short-term administration of R73 at relatively low doses before immunization with encephalitogenic antigen, myelin basic protein (MBP), prevented the development of EAE. However, treatment with anti-CD4 and anti-Ia mAb in the same protocol was ineffective. Flow cytometric analysis demonstrated that short-term administration of R73 resulted in transient down-regulation of the TcR molecules, whereas the number of CD2-expressing T cells was well preserved. Furthermore, the response to MBP of T cells isolated from rats that were pretreated with R73 and then immunized with MBP was strongly suppressed. On the other hand, the T-cell response of R73-pretreated rats to a third-party antigen which was immunized at a later period was not inhibited. These findings suggest that in vivo administration of a low dose of R73 protects rats from EAE by inducing anergy of MBP-reactive encephalitogenic T cells. Furthermore, R73 treatment which started on day 10 of the immunization (shortly before the day of onset of clinical signs) completely suppressed the induction of EAE and that which started on day 11 (the day of onset) hastened recovery. Since the phenotypes of the TcR V beta chain of encephalitogenic T cells are not so limited as previously believed, immunotherapy with mAb against the TcR alpha beta framework may be one of the best methods for treatment of T-cell-mediated autoimmune diseases.     

Immunoregulation of encephalitogenic MBP-NAc1-11-reactive T cells by CD4+ TCR-specific T cells involves IL-4, IL-10 and IFN-gamma

The generation of TCR transgenic (Tg) mice expressing a BV8S2 (Vbeta8 subfamily 2) chain specific for the encephalitogenic NAc1-11 region of MBP provides a unique system for evaluating the mechanisms involved in anti-TCR immunoregulation of EAE. In a previous study, we showed that vaccination with BV8S2 protein induced specific T cells that inhibited proliferation responses and encephalitogenic activity of MBP-reactive T cells in vitro, and resulted in a skewed production of Th2 cytokines by the MBP-reactive T cells. These data suggested that regulation of the encephalitogenic T cells was mediated by inhibitory cytokines rather than through a deletional mechanism. In the current study, we have employed the BV8S2 Tg mouse model to address the issue of which cytokines produced by anti-TCR-reactive T cells can regulate the function of encephalitogenic Th1 cells. Utilizing neutralizing anti-cytokine antibodies to reverse inhibitory effects of supernatants from BV8S2-specific T cells, we found that IL-4, IL-10, and to a lesser extent, IFN-gamma and TGF-beta, were the major regulatory cytokines responsible for inhibiting encephalitogenic activity, proliferation, and IFN-gamma secretion of MBP-NAc1-11-reactive Th1 cells. These results indicate that cytokine regulation is the major mechanism through which TCR specific CD4+ T cells regulate encephalitogenic and potentially other bystander Th1 cells.     

Differential activation of human autoreactive T cell clones by altered peptide ligands derived from myelin basic protein peptide (87–99)

We have examined the functional consequences induced by interaction of DR2a-restricted myelin basic protein (MBP) (87–99)-specific T cell clones (TCC) with altered peptide ligands (APL) derived from MBP peptide (87–99). The immunodominant MBP peptide (87–99) has been implicated as a candidate antigen in multiple sclerosis (MS) by several lines of evidence. In the present study, we have defined the T cell receptor (TCR) contact residues for DR2a-restricted, (87–99)-specific T helper type 1 T cells to design APL suitable to modify the functions of such T cells potentially relevant for the pathogenesis of MS. We show that neutral (L-alanine substitutions) or conservative exchanges of the primary and secondary TCR contact residues lead to various alterations of T cell function, ranging from differences in interleukin-2 receptor up-regulation to anergy induction and TCR antagonism. The potential usefulness of APL as an immunomodulating therapy for DR2⁺ MS patients is discussed.     

The role of CTLA-4 in tolerance induction and ttigen administration cell differentiation in experimental autoimmune encephalomyelitis: i. v. antigen administration

Interactions between B7 molecules on antigen-presenting cells and CTLA-4 on T cells have been shown to be important in establishing tolerance. In the present study, we examined the kinetics of tolerance induction following i.v. administration of myelin basic protein (MBP) Ac1-11 in mice transgenic for a TCR V(beta)8.2 gene derived from an encephalitogenic T cell clone specific for MBP Ac1-11. Examination of the lymph node cell (LNC) response 10 days after antigen administration demonstrated an accentuation of i.v. tolerance induction with anti-CTLA-4 blockade. Anergy was induced in splenocytes by i.v. antigen administration as shown by a decrease in MBP-specific proliferation and IL-2 production, and anti-CTLA-4 potentiated this effect. In addition, i.v. antigen plus anti-CTLA-4 and complete Freund's adjuvant was not encephalitogenic. Interestingly, i.v. tolerance (a single injection) did not inhibit experimental autoimmune encephalomyelitis (EAE) and anti-CTLA-4 administration did not alter this phenotype. These results suggest that while the majority of MBP-specific T cells are tolerized by i.v. antigen and that this process is potentiated by anti-CTLA-4 administration, a population of T cells remains that is quite efficient in mediating EAE.     

Dominant V beta 8 gene usage in response to TNP: failure to use other V beta chains following removal of V beta 8+ T cells by monoclonal antibody in vivo.

This paper investigates the V beta usage of lymph node cells from mice immunized with TNP and of cell lines made from them. In cell lines stimulated weekly with TNP in vitro for 1 month, about 87% of the cells were V beta 8+ and further analysis showed that these cells were actually V beta 8.2+. This was also true for the cells that proliferated in lymph nodes in response to TNP 4 days after primary immunization, i.e. proliferation occurred mainly in the V beta 8+, and in particular in the V beta 8.2+, population while much less proliferation occurred when the V beta 8- or V beta 8.2- T-cell populations are used. This was not due to non-specific damage during separation, as the response to concanavalin A and alloantigen was intact. In a separate series of experiments, mice were acutely depleted of V beta 8+ T cells by treatment with F23.1 or a control monoclonal antibody (mAb) in vivo given before immunization. Treatment with the relevant mAb virtually abolished the response to TNP. In contrast, SJL mice, which lack the gene segment coding for the V beta 8 family and several other V beta chains, made a normal proliferative and delayed-type hypersensitivity (DTH) response to TNP. This poses the problem, which may be important in the study of the T-cell repertoire, of why acute removal of V beta 8+ T cells, which are dominantly used in the response to TNP, does not allow T cells using other chains to substitute in the response, while the absence of this population over a long period of time, because of a deletion in the genome, allows the use of T cells bearing other V beta chains.