Expansion of neonatal tolerance to self in adult life: II. Tolerance preferentially spreads in an intramolecular manner
Nir Grabie1 and
Nathan Karin1,2
1 Department of Immunology, Bruce Rappaport Faculty of Medicine and
2 Rappaport Family Institute for Research in the Medical Sciences, Technion, POB 9697, Haifa 31096, Israel
Correspondence to:
N. Karin
 |
Abstract
|
---|
Newborn rats exposed to a myelin basic protein determinant acquired long-lasting resistance to experimental autoimmune encephalomyelitis induced by another determinant only if both determinants are co-administered in adult life. We demonstrate here that during the course of disease both the anti-self response and the tolerant state spread in an intramolecular and not an intermolecular manner. Mechanisms involved in tolerance elicitation and expansion are then explored using an in vitro system in which indirect suppression could be measured.
Keywords: experimental autoimmune encephalomyelitis, IL-4, intramolecular deviation, multiple sclerosis, neonatal tolerance, Th1, Th2, tolerizing T cells.
 |
Introduction
|
---|
The embryonic and neonatal periods have been thought of as a window in ontogeny during which the developing immune system is particularly susceptible to tolerization. Thus, antigenic challenge in neonatal life may result in specific T cell unresponsiveness in the adult (15). Antigen-specific T cell deletion was suggested to be a pivotal mechanism by which central tolerance, including tolerance to neonatally administered antigens, is induced and maintained (6,7).
Based on their cytokine profile CD4+ T cells fall into at least four subfamilies: Th1 cells that produce large amounts of IFN-
and tumor necrosis factor (TNF)-
, but to a much lesser extent IL-4 or IL-10; Th2 cells that produce IL-4, IL-10, IL-13 and, to a much lesser extent, IFN-
and TNF-
(817); Th3 cells that produce high amounts of transforming growth factor-ß (18); and the newly discovered Tr1 cells that produce IL-10 with no production of IL-4 (19). Alteration of the balance between antigen-specific T cell subsets, in favor of tolerizing T cell selection, rather than T cell elimination, has recently been suggested as a major mechanism by which the tolerant state in neonatal tolerance is induced and maintained (2023).
We have used experimental autoimmune encephalomyelitis (EAE), a well-defined model of T cell-mediated autoimmune disease of the central nervous system (CNS), to explore basic concepts in tolerance to self (2426). These studies determined, at the molecular level, the minimal requirements for initiation of antigen-specific peripheral T cell tolerance (24,27), which could be reversed in vivo by neutralizing antibodies to IL-4 (26). The current study uses this well-defined model to explore basic concepts in expansion of tolerance to self.
In EAE the autoimmune response of T cells to components of CNS begins with recognition of a single or limited number of self-determinants and expands into a reaction to several self-determinants on the same molecule, termed intramolecular epitope spreading (2831). Possible expansion of the response to other molecules within the nervous system would then be termed intermolecular epitope spreading. Lewis rats immunized with myelin basic protein (MBP) emulsified in complete Freund's adjuvant (CFA) to induce active EAE first mount a primary T cell response to an encephalitogenic epitope encompassed within residues 6886 (p6886) of MBP and then to a secondary epitope consisting of residues 8799 (p8799) (28,29). These epitopes do not share cross-reactive determinants. Yet, immunization of Lewis rats with one of these determinants induces a response that spreads to the other one (3,31). This type of response involving epitope spreading has also been named a `trans-acting' or `cryptic' response (2,3,3032). Another major component of myelin in the CNS is the proteolipid apo-protein (PLP). The epitope contained between residues 217 and 240 of PLP in its acetylated form (PLP Ac217240) is encephalitogenic in the Lewis rat (33) and does not cross-activate MBP-specific T cells. P2 is an antigen exclusively expressed in the peripheral nervous system. Experimental autoimmune neuritis (EAN) is a T cell-mediated autoimmune disease of the peripheral nervous system induced by the 5781 residues of bovine P2 emulsified in CFA (34), which does not cross-activate MBP-specific T cells nor PLP-specific T cells. We have used the above system to explore possible intramolecular, intermolecular and organ-specific expansion of tolerance to self.
The current study demonstrates that perturbation of the antigen-specific T cell balance is involved in maintaining the tolerant state of neonatally tolerized T cells, and demonstrates that the antigen-specific T cell proliferative response and the expansion of tolerance to self both spread in a similar manner. Most importantly, it also brings evidence to suggest that the deviation of `neonatally tolerizing' T cells occurs peripherally during adult life.
 |
Methods
|
---|
Rats
Pregnant Lewis rats were purchased from Harlan (Jerusalem, Israel) ~5 days before expected delivery and kept under pathogen-free conditions at our animal facility.
Peptide antigens
MBP p8799, VHFFKNIVTPRTP, MBP p6886, YGSLPQKSQRSQDENPV, P2 p5783 (34), and PLP pAc 224240, Ac-LSICKTAEFQMTFHLFI-NH were all synthesized on a MilliGen 9050 peptide synthesizer by standard 9-fluorenylmethoxycarbonyl chemistry. Peptides were purified by HPLC. Structure was confirmed by amino acid analysis and mass spectroscopy. Only peptides that were >95% pure were used in our study.
Induction of neonatal tolerance
MBP, P2 and PLP peptides at a concentration of 1 mg/ml were dissolved in PBS and emulsified with an equal volume of incomplete Freund's adjuvant (IFA; Difco, Detroit, MI). Within the first 2472 h after birth newborn rats were immunized i.p. with 0.1 ml of the emulsion. Only female rats were later selected for experiments.
Active EAE or EAN induction
MBP p6886, MBP p8799, P2 p5783 or PLP Ac 224240 peptides at a concentration of 1 mg/ml were dissolved in PBS and emulsified with an equal volume of IFA supplemented with 4 mg/ml heat-killed Mycobacterium tuberculosis (MT) H37Ra in oil (Difco). At 68 weeks of age rats were immunized s.c. in the hind footpads with 0.1 ml of the emulsion and monitored daily for clinical signs by an observer blind to the treatment protocol. EAE was scored as follows: 0, clinically normal; 1, flaccid tail; 2, hind limb paralysis; 3, front and hind limb paralysis; 4, total body paralysis (36). EAN was scored as follows: 0, clinically normal; 1, flaccid tail; 2, hind limb paralysis.
Both EAE and EAN display a similar clinical manifestation. Because P2 and MBP peptides were, in some experiments, injected to the same recipient, development of each disease was histologically verified by evaluating the elaboration of an inflammatory process in sections from ischiatic nerve and from the CNS, using a protocol we have described in detail elsewhere (35).
Antigen-specific T cell proliferation assays
Lewis rats were immunized with various MBP peptides as described above. Nine to 10 days later, draining lymph node cells or spleen cells were suspended in stimulation medium that included Dulbecco's modified Eagle's medium (Biological Industries, Kibbutz Beit-Haemek, Israel) supplemented with 2-mercaptoethanol (5x105 M), L-glutamine (2 mM), sodium pyruvate (1 mM), penicillin (100 µ/ml), streptomycin (100 µg/ml) and 1% heat-inactivated normal Lewis rat serum. Cells were then cultured in U-shape 96-well microculture plates (2x105 cells/well) for 72 h at 37°C in humidified air containing 7.5% CO2. In the trans-acting antigen-specific proliferation assay, spleen cells (2x105 cells/well) were plated together with MT (10 µg/ml) with or without additional MBP peptides at various concentrations. Each well was pulsed with 2 µCi of [3H]thymidine (sp. act. 10 Ci/mmol) for the final 18 h. The cultures were then harvested on fiberglass filters and the proliferative response expressed as c.p.m. ± SD or as stimulation index (SI) (mean c.p.m. of test cultures divided by mean c.p.m. of control cultures).
Cytokine determination
Spleen cells were stimulated in vitro (107 cells/ml) in 24-well plates (Nunc, Roskilde, Denmark) with 100 µM p6886. After 48 h of stimulation, supernatants were assayed by semi-ELISA kits, that include antibody pairs and recombinant rat cytokines, as follows: IFN-
, rabbit anti-rat IFN-
polyclonal antibody (CY-048; Innogenetics, Zwijlnaarde, Belgium) as a capture antibody, biotinylated mouse anti-rat mAb (CY-106 clone BD-1, Innogenetics) as a detection antibody and alkaline phosphatasestreptavidin (cat no. 43-4322; Zymed, San Francisco, CA) with rat recombinant IFN-
as a standard (cat. no. 3281SA; Gibco/BRL, Gaithersburg, MD); IL-10, commercial semi-ELISA kit for the detection of rat IL-10 (PharMingen, San Diego, CA); IL-4, mouse anti-rat IL-4 mAb (24050D OX-81; PharMingen) as a capture antibody, and rabbit anti-rat IL-4 biotin-conjugated polyclonal antibody (2411-2D; PharMingen) as second antibody. Recombinant rat IL-4 purchased from R & D Systems (Minneapolis, MN; 504-RL) was used as a standard.
Statistical analysis
Significance of differences was examined using Student's t-test. A value of P < 0.05 was considered significant.
 |
Results
|
---|
Intramolecular but not intermolecular spread of the T cell response to encephalitogenic determinants at the onset of active EAE
Determinant spread in the CNS was determined at the onset of active EAE. Lewis rats were immunized with either the major encephalitogenic determinant of MBP (MBP p6886/CFA), the secondary determinant on the same molecule (MBP p8799) or by an encephalitogenic determinant located on another molecule in the CNS (PLP pAc 224240). Ten days later, three out of nine rats in each group were evaluated for the development of a splenic T cell response against each of the above non-cross-reactive determinants (Table 1
), while the other rats were kept for evaluation of clinical and histological manifestation of disease. All three peptides were encephalitogenic under our working conditions (MBP p6886/CFA: incidence six of six, first day of onset 10 ± 0, mean maximal clinical score 2.66 ± 0.23; MBP p8799/CFA: incidence six of six, first day of onset 12 ± 0, mean maximal clinical score 2.16 ± 0.18; PLP pAc 224240/CFA: incidence four of six, first day of onset 11 ± 0, mean maximal clinical score 0.66 ± 0.23). Splenic T cells from rats immunized with p6886/CFA exhibited a profound proliferative response to the immunizing peptide (Table 1a
, SI = 7.1 ± 0.9) that spread to the other linked determinant (Table 1a
, SI = 4.5 ± 0.6) but not to PLP pAc 224240 (Table 1a
, SI = 1.5 ± 0.3). Similarly, splenic T cells from rats immunized with p8799/CFA displayed a significant proliferative response to the immunizing peptide (Table 1b
, SI = 5.8 ± 0.4) that spread to the other linked determinant (Table 1b
, SI = 5.4 ± 0.3) but not to PLP pAc 224240 (Table 1b
, SI = 1.2 ± 0.1). Splenic T cells from rats immunized with PLP pAc 224240/CFA (Table 1c
) developed a significant response that did not spread to either of the MBP encephalitogenic determinants in the CNS nor to the immunodominant determinant of P2 (P2 p5781) which is exclusively expressed in the peripheral nervous system. All cultured spleen T cells displayed a similar primary T cell response against MT which was present in the Freund's adjuvant, with which each peptide was administered (Table 1
). Thus, at the onset of EAE, the T cell response against CNS encephalitogenic determinants spreads in an intramolecular rather than intermolecular manner.
Intramolecular but not intermolecular expansion of tolerance to self in neonatally tolerized rats
Newborn rats exposed to MBP p8799 within the first 2472 h after birth acquired long-lasting resistance to EAE induced by this same peptide in later life (Table 2c
versus a, none of six versus six of six with a maximal clinical score of 2.2 ± 0.1, P < 0.001) and not by MBP p6886/CFA (Table 2f
, six of six with a maximal clinical score of 2.2 ± 0.2). The tolerant state could be extended to the other linked MBP determinant only if the neonatally tolerizing determinant was simultaneously injected in adult life together with CFA (Table 2i
versus f and d, incidence one of six versus six of six in each group, with a mean maximal clinical score of 0.16 ± 0.18 versus 2.25 ± 0.2, and 2.5 ± 0.2, P < 0.001 for each comparison, no significant difference between Table 2f and d
).
Ovalbumin could be used as a tolerizing determinant against itself (Fig. 1e
). Nevertheless, rats treated neonatally with ovalbumin/IFA and challenged with MBP p6886/CFA plus ovalbumin/CFA in adult life did not demonstrate any EAE resistance (Table 2k
). Ovalbumin failed to induce trans-acting neonatal tolerance either because it was not continually accessible to the immune system, because it was not displayed in proximity to the encephalitogenic determinant at the site of inflammation (i.e. the brain) or because it was not part of the same molecule. To further assess this question the last experiment was repeated using the neuritogenic epitope of P2 (P2 p5783), rather than ovalbumin, as a tolerizing determinant. This determinant is exclusively expressed in the peripheral nervous system and can be used as a powerful tolerizing determinant (Fig. 1d
, SI = 3.5 ± 0.2 versus 9.2 ± 0.5, P < 0.001). Thus, Lewis rats tolerized with P2 p5783/IFA and exposed to a subsequent immunization of P2 p5783/CFA + MBP p6886/CFA were evaluated for resistance to either neuritis or EAE. These rats were markedly resistant to neuritis (incidence of none of six versus six of six sick rats), but yet highly susceptible to EAE (Table 2g
, six of six mean maximal score of 2.4 ± 0.2). Thus, exposure to a tolerizing determinant that is not organ specific is irrelevant to the EAE system even though the tolerizing antigen is a persistent antigen at a distant point in the nervous system.

View larger version (20K):
[in this window]
[in a new window]
|
Fig. 1. Unresponsiveness to various self and foreign determinants in neonatally tolerized Lewis rats. MBP p6886, MBP p8799, P2 p5783 or PLP Ac 224240 peptides and ovalbumin (grade VII; Sigma) at a concentration of 1 mg/ml were dissolved in PBS and emulsified with an equal volume of either IFA or with an equal volume of IFA supplemented with 4 mg/ml heat-killed MT H37Ra in oil (CFA; Difco). Within the first 2472 h after birth newborn rats were immunized i.p. with 0.1 ml of each peptide emulsified with IFA (gray bars) or with IFA alone (empty bars). At 6 weeks of age these rats were s.c. challenged, in the hind footpads, with 0.1 ml of each reciprocal CFA emulsion. Ten days later splenic T cells were cultured together with 100 µg/ml of each of the immunizing peptides. Results of quadruplicates are shown as SI ± SE.
|
|
Similarly to MBP, PLP is highly expressed in the CNS and can be used as a powerful tolerizing determinant against self (Fig. 1c
, SI = 1.5 ± 0.3 versus 4.5 ± 0.3, P < 0.001). Similarly to the P2 results, adult immunization with PLP pAc 224240/CFA of rats that were neonatally exposed to this epitope did not render them resistant to EAE induced by MBP p6886 (Table 2h
, six of six, mean maximal score 2.08 ± 0.17). Taken together these results suggest that epitope spread of neonatal tolerance requires not only the presence of each determinant at the target organ, but also their co-expression on the same molecule.
Once a tolerant state has been established it can spread in vivo in an intramolecular, but not intermolecular, manner. Thus, rats neonatally tolerized and subsequently challenged in adult life with MBP p8799 displayed a markedly reduced primary splenic T cell response not only to MBP p8799 (Fig. 2b
versus a, 1.1 ± 0.5 versus 5.8 ± 0.5, P < 0.001), but also to the linked determinant, MBP p6886 (Fig. 2d
versus c, 2.3 ± 0.8 versus 6.1 ± 0.2, P < 0.001). These results are highly interesting since MBP p6886 was not administered experimentally during the neonatal period nor in adult life. Rats that were neonatally administered with p8799/IFA and then in adult life with p8799/CFA + PLP pAc 224240/CFA exhibited a markedly reduced T cell response against p6886 (Table 3i
, SI = 1.2 ± 0.1), but not against PLP pAc 224240 (Table 3i,
4.7 ± 0.3). This demonstrates, once again, that a tolerant state spreads in an intramolecular, but not intermolecular, manner.

View larger version (36K):
[in this window]
[in a new window]
|
Fig. 2. Reversal of trans-acting suppression by IL-4-specific neutralizing antibodies. MBP p8799 at a concentration of 1 mg/ml was dissolved in PBS and emulsified with an equal volume of IFA. Within the first 2472 h after birth newborn rats were immunized i.p. with 0.1 ml of the above emulsion (b, d, f, h, j, l, n and p) or with IFA alone (a, c, e, g, i, k, m and o). At 6 weeks of age these rats were all challenged with MBP p8799 /CFA. Ten days later splenic T cells were cultured together with either MBP p8799, MBP p6886, MBP p8799, P2 p5783 or PLP Ac 224240 peptides (100 µg/ml), MT (100 µg/ml) or their combination, with or without the addition of anti-IL-4 neutralizing antibodies (rabbit anti-rat IL-4 polyclonal antibody 2411-2D) at a final concentration of 150 ng/ml. Result of the proliferation assay of each group (quadruplicates) are shown as SI ± SE.
|
|
Immunological mechanism of determinant spread
Determinant spread of a tolerant state may be explained, in part, by antigen-specific active suppression. Spleen cells from rats tolerized neonatally with p8799/IFA that were obtained 9 days after adult challenge with the tolerizing epitope and cultured for 48 h in stimulation medium exhibited a profound increase in IL-4 production (250 versus 10 pg/ml in cultured spleen T cells from control EAE rats, P < 0.0001). The above increase was accompanied by a significant reduction in IFN-
production (2.5 versus 40 ng/ml). Thus, alteration of the balance of antigen-specific T cells might be involved in the induction, maintenance and intramolecular expansion of tolerance to self. To further investigate this possibility, an in vitro system in which indirect (trans-acting) suppression could be measured has been utilized. Addition of the tolerizing epitope (MBP p8799) to splenic T cells from MBP p8799/IFA-tolerized animals that were challenged with MBP p8799/CFA in adult life induced a marked trans-acting suppression of their anti-MT response (Fig. 2
versus f, 2.1 ± 0.6 versus 14.1 ± 1.34, P < 0.001). This response could be restored by IL-4-specific neutralizing antibodies (Fig. 2h
, SI = 7.8 ± 1.1). Addition of the MBP p8799 epitope to cultures of splenic T cells from non-tolerized EAE animals did not induce trans-acting suppression of their anti-MT response (Fig. 2a
). Surprisingly, addition of MBP p6886 to splenic T cells from rats that were neonatally administered with MBP p8799/IFA and subsequently challenged with MBP p8799/CFA as adults induced a marked suppression in the proliferative response to MT (Fig. 2d
versus c, 1.5 ± 0.2 compared with 10.5 ± 1.3, P < 0.001). Again this trans-acting response could be reinstated by IL-4-specific neutralizing antibodies (Fig. 2d
versus c, 8.1 ± 1.3 versus 10.2 ± 0.9). These results are remarkable since the target determinant p6886 was not administered during the neonatal period nor to the adult. These experiments provide indirect evidence for peripheral targeted deviation of neonatally tolerized T cells during adult life. Addition of PLP pAc 224240 to the above cultured T cells proliferating in response to MT did not affect their response (Fig. 2n
). Thus we demonstrate here, for the first time, intramolecular, but not intermolecular, expansion of tolerance to self and suggest a mechanism that explains this spreading, as discussed below.
 |
Discussion
|
---|
Negative selection in the thymus is a major mechanism by which many, but not all, self-reactive T cells, including those reacting against antigens administered at the neonatal period of life, are eliminated (25). This type of T cell tolerance has also been referred to as central tolerance (6,7). It is apparent that autoreactive T cells do escape thymic selection, and can be identified in both healthy individuals and those suffering form self-destructive autoimmune diseases (37). In healthy individuals, self tolerance is maintained in part through mechanisms acting outside the thymus that keep these autoreactive lymphocytes under control. This type of T cell tolerance has also been termed peripheral tolerance (38). T cell anergy (39), active suppression (3943) and T cell deletion (44,45) contribute to the maintenance of a tolerant state in peripheral tolerance. The anti-inflammatory cytokine IL-4 is a key mediator in peripheral T cell tolerance (46). Thus, perturbation of the Th1/Th2 balance towards IL-4-producing Th2 cells restrains the harmful activity of autoimmune Th1 cells (42,43,4749), whereas IL-4 neutralizing antibodies reinstate EAE susceptibility in peripherally tolerized animals (26). The data presented in our study, together with accumulating data from other laboratories (2023), demonstrate that alteration of the antigen-specific balance of CD4+ T cells, rather than across the board T cell elimination, plays a pivotal role in neonatal tolerance as well. Considering that neonatal tolerance represents immunological processes that are associated with central tolerance, we suggest that IL-4-dependent T cell perturbation is a key mechanism by which both central and peripheral tolerance are maintained (Fig. 2
).
Epitope spread at a target organ has recently been explored in EAE (2931) and insulin-dependent diabetes in the NOD mouse (50). We have previously used molecular biologic techniques to demonstrate that T cell homing to the site of inflammation, in this case the brain, is a multi-sequential event that includes a selective stage in which antigen-specific T cells interact with their target antigen resulting in activation of the bloodbrain barrier to allow the accumulation of a non-selective influx of endogenous T cells into the CNS which correlates with disease onset (2527,35). It is therefore likely that epitope spreading entails non-selective entrance of inactivated circulating T cells into the CNS during the inflammatory breach in the bloodbrain barrier and their activation, possibly for the first time, at the site of inflammation. The above hypothesis cannot fully explain preferential intramolecular, rather than intermolecular spreading of the immune response against self, as was detected in our experimental system (Table 1
). Interestingly, the tolerant state in neonatally tolerized animals expands in an intramolecular rather than intermolecular manner (Tables 2 and 3
). The biological rational is apparent in that there is no obvious reason why the immune response should generate protective immunity to restrain a response that has not been turned on. Nevertheless, the underlying mechanism at the cellular and molecular level is not yet fully understood. Our results show that addition of a tolerizing determinant to cultured primary T cells from tolerized animals suppresses their response to MT and that IL-4-specific neutralizing antibodies can reinstate this trans-acting proliferative response (Fig. 2
) provide a partial explanation for the mechanism of tolerance spread. Determinant spread of a tolerant state between various antigenic determinants has also been characterized for determinants associated with the development of diabetes in NOD mice (50) and myasthenia gravis (51). Our study, nevertheless, demonstrates for the first time a correlation between spread of T cell response and of T cell tolerance, and provides indirect evidence to support targeted deviation of tolerizing T cells at an autoimmune site.
 |
Acknowledgments
|
---|
We would like to thank Dr H. Gershon for creative discussions and for reading the manuscript. This study was supported by Israel Cancer Research Foundation (ICRF), Israel Science Foundation, Israel Ministry of Science and Arts, Israel Ministry of Health, and the Technion VPRAlbert Goodstein Fund.
 |
Abbreviations
|
---|
CFA | complete Freund's adjuvant |
CNS | central nervous system |
EAE | experimental autoimmune encephalomyelitis |
EAN | experimental autoimmune neuritis |
IFA | incomplete Freund's adjuvant |
MBP | myelin basic protein |
PLP | proteolipid apo-protein |
SI | stimulation index |
TNF | tumor necrosis factor |
 |
Notes
|
---|
Transmitting editor: L. Steinman
Received 12 January 1999,
accepted 17 February 1999.
 |
References
|
---|
-
Qin, Y. F., Sun, D. M., Goto, M., Meyermann, R. and Wekerle, H. 1989. Resistance to experimental autoimmune encephalomyelitis induced by neonatal tolerization to myelin basic protein: clonal elimination vs. regulation of autoaggressive lymphocytes. Eur. J. Immunol. 19:373.[ISI][Medline]
-
Clayton, J. P., Gammon, G. M., Ando, D. G., Kono, D. H., Hood, L. and Sercarz, E. E. 1989. Peptide-specific prevention of experimental allergic encephalomyelitis. Neonatal tolerance induced to the dominant T cell determinant of myelin basic protein. J. Exp. Med. 169:1681.[Abstract]
-
Vandenbark, A. A., Vainiene, M., Celnik, B., Hashim, G. A., Buenafe, A. and Offner, H. 1994. Definition of encephalitogenic and immunodominant epitopes of guinea pig myelin basic protein (Gp-BP) in Lewis rats tolerized neonatally with Gp-BP or Gp-BP peptides. J. Immunol. 153:852.[Abstract/Free Full Text]
-
Gammon, G. M., Oki, A., Shastri, N. and Sercarz, E. E. 1986. Induction of tolerance to one determinant on a synthetic peptide does not affect the response to a second linked determinant. Implications for the mechanism of neonatal tolerance induction. J. Exp. Med. 164:667.[Abstract]
-
Gammon, G., Don, K., Shastri, N., Oki, A., Wilbur, S. and Sercarz, E. E. 1986. Neonatal T-cell tolerance to minimal immunogenic peptides is caused by clonal inactivation. Nature 309:413.
-
Ramsdell, F. and Fowlkes, B. J. 1990. Clonal deletion versus clonal anergy: the role of the thymus in inducing self tolerance. Science 248:1342.[ISI][Medline]
-
Kappler, J., Roehm, N. and Marrack, P. 1987. T cell tolerance by clonal elemination in the thymus. Cell 49:273.[ISI][Medline]
-
O'Garra, A. and Murphy, K. 1994. Role of cytokines in determining T-lymphocyte function. Curr. Opin. Immunol. 6:458.[ISI][Medline]
-
Abbas, A. K., Murphy, K. M. and Sher, A. 1996. Functional diversity of helper T lymphocytes. Nature 383:787.[ISI][Medline]
-
Swain, S. L., Weinberg, A. D., English, M. and Huston, G. 1990. IL-4 directs the development of Th2-like helper effectors. J. Immunol. 145:3796.[Abstract/Free Full Text]
-
Lederer, J. A., Perez, V. L., DesRoches, L., Kim, S. M., Abbas, A. K. and Lichtman, A. H. 1996. Cytokine transcriptional events during helper T cell subset differentiation. J. Exp. Med. 184:397.[Abstract]
-
Seder, R. A., Gazzinelli, R., Sher, A. and Paul, W. E. 1993. IL-12 acts directly on CD4+ T cells to enhance priming for IFN-g production and diminishes IL-4 inhibition of such priming. Proc. Natl Acad. Sci. USA 90:10188.[Abstract]
-
Seder, R. A., Paul, W. E., Davis, M. M. and Fazekas de St. Groth, B. 1992. The presence of interleukin-4 during in vitro priming determines the cytokine-producing potential of CD4+ T cells from T cell receptor transgenic mice. J. Exp. Med. 176:1091.[Abstract]
-
Fiorentino, D. F., Zlotnik, A., Vieira, P., Mosmann, T. R., Howard, M., Moore, K. W. and O'garra, A. 1991. IL-10 acts on the antigen presenting cell to inhibit cytokine production by Th1 cells. J. Immunol. 146:3444.[Abstract/Free Full Text]
-
Mosmann, T. R. and Coffman, R. L. 1989. Th1 and Th2 cells: different patterns of lymphokine secretion lead to different functional properties. Annu. Rev. Immunol. 9:145.
-
Mosmann, T. and Moor, K. 1989. The role of IL-10 in the crossregulation of Th1 and Th2 responses. Immunol. Today 12:A49.
-
Huang, H., Hu-Li, J., Chen, H., Ben-Sasson, S. Z. and Paul, W. E. 1997. IL-4 and IL-13 production in differentiated T helper type 2 cells is not IL-4 dependent. J. Immunol. 159:3731.[Abstract]
-
Fukaura, H., Kent, S. C., Pietrusewicz, M. J., Khoury, S. J., Weiner, H. L. and Hafler, D. A. 1996. Induction of circulating myelin basic protein and proteolipid protein-specific transforming growth factor-beta1-secreting Th3 T cells by oral administration of myelin in multiple sclerosis patients. J. Clin. Invest. 98:70.[Abstract/Free Full Text]
-
Groux, H., O'Garra, A., Bigler, M., Rouleau, M., Antonenko, S., de Vries, J. E. and Roncarolo, M. G. 1997. A CD4+ T-cell subset inhibits antigen-specific T-cell responses and prevents colitis. Nature 389:737.[ISI][Medline]
-
Singh, R. R., Hahn, B. H. and Sercarz, E. E. 1996. Neonatal peptide exposure can prime T cells and, upon subsequent immunization, induce their immune deviation: implications for antibody vs. T cell-mediated autoimmunity [see comments]. J. Exp. Med. 183:1613.[Abstract]
-
Forsthuber, T., Yip, H. C. and Lehmann, P. V. 1996. Induction of TH1 and TH2 immunity in neonatal mice [see comments]. Science 271:1728.[Abstract]
-
Sarzotti, M., Robbins, D. S. and Hoffman, P. M. 1996. Induction of protective CTL responses in newborn mice by a murine retrovirus [see comments]. Science 271:1726.[Abstract]
-
Ridge, J. P., Fuchs, E. J. and Matzinger, P. 1996. Neonatal tolerance revisited: turning on newborn T cells with dendritic cells [see comments]. Science 271:1723.[Abstract]
-
Karin, N., Binah, O., Grabie, N., Mitchel, D. J., Felzen, B., Solomon, M. D., Conlon, P., Gaur, A., Ling, N. and Steinman, L. 1998. Short peptide based tolerogens without antigenic activity reverse autoimmunity. J. Immunol. 160:5188.[Abstract/Free Full Text]
-
Karin, N., Mitchell, J. D., Brocke, S., Ling, N. and Steinman, L. 1994. Reversal of experimental autoimmune encephalomyelitis by as soluble peptide variant of a myelin basic protein epitope: T cell receptor antagonism and reduction of IFN-
and TNF-
production. J. Exp. Med. 180:2227.[Abstract]
-
Brocke, S., Gijbels, K., Allegretta, M., Ferber, I., Piercy, C., Blankenstein, T., Martin, R., Utz, U., Karin, N., Mitchell, D., et al. 1996. Treatment of experimental encephalomyelitis with a peptide analogue of myelin basic protein. Nature 379:343.[ISI][Medline]
-
Karin, N., Szafer, F., Mitchell, D., Gold, D. P. and Steinman, L. 1993. Selective and nonselective stages in homing of T lymphocytes to the central nervous system during experimental allergic encephalomyelitis. J. Immunol. 150:4116.[Abstract/Free Full Text]
-
Offner, H., Hashim, G. A., Celnik, B., Galang, A., Li, X. B., Burns, F. R., Shen, N., Heber- Katz, E. and Vandenbark, A. A. 1989. T cell determinants of myelin basic protein include a unique encephalitogenic I-E-restricted epitope for Lewis rats. J. Exp. Med. 170:355.[Abstract]
-
Offner, H., Vainiene, M., Gold, D. P., Celnik, B., Wang, R., Hashim, G. A. and Vandenbark, A. A. 1992. Characterization of the immune response to a secondary encephalitogenic epitope of basic protein in Lewis rats. I. T cell receptor peptide regulation of T cell clones expressing cross-reactive V beta genes. J. Immunol. 148:1706.[Abstract/Free Full Text]
-
Lehmann, P. V., Forsthuber, T., Miller, A. and Sercarz, E. E. 1992. Spreading of T-cell autoimmunity to cryptic determinants of an autoantigen. Nature 358:155.[ISI][Medline]
-
Mor, F. and Cohen, I. R. 1993. Shifts in the epitopes of myelin basic protein recognized by Lewis rat T cells before, during, and after the induction of experimental autoimmune encephalomyelitis. J. Clin. Invest. 92:2199.[ISI][Medline]
-
McRae, B. L., Vanderlugt, C. L., Dal Canto, M. C. and Miller, S. D. 1995. Functional evidence for epitope spreading in the relapsing pathology of experimental autoimmune encephalomyelitis. J. Exp. Med. 182:75.[Abstract]
-
Zhao, W., Wegmann, K. W., Trotter, J. L., Ueno, K. and Hickey, W. F. 1994. Identification of an N-terminally acetylated encephalitogenic epitope in myelin proteolipid apoprotein for the Lewis rat. J. Immunol. 153:901.[Abstract/Free Full Text]
-
Olee, T., Powers, J. M. and Brostoff, S. W. 1988. A T cell epitope for experimental allergic neuritis. J. Neuroimmunol. 19:167.[ISI][Medline]
-
Yednock, T. A., Cannon, C., Fritz, L. C., Sanchez, M. F., Steinman, L. and Karin, N. 1992. Prevention of experimental autoimmune encephalomyelitis by antibodies against alpha 4 beta 1 integrin. Nature 356:63.[ISI][Medline]
-
Ben-Nun, A., Wekerle, H. and Cohen, I. R. 1981. The rapid isolation of clonable antigen-specific T lymphocyte lines capable of mediating autoimmune encephalomyelitis. Eur. J. Immunol. 11:195.[ISI][Medline]
-
Pette, M., Fujita, K., Kitze, B., Whitaker, J. N., Albert, E., Kappos, L. and Wekerle, H. 1990. Myelin basic protein-specific T lymphocyte lines from MS patients and healthy individuals. Neurology 40:1770.[Abstract]
-
Steinman, L. 1995. Escape from `horror autotoxicus': pathogenesis and treatment of autoimmune disease. Cell 80:7.[ISI][Medline]
-
Friedman, A. and Weiner, H. L. 1994. Induction of anergy or active suppression following oral tolerance is determined by antigen dosage. Proc. Natl Acad. Sci. USA 91:6688.[Abstract]
-
Chen, Y., Kuchroo, V. K., Inobe, J., Hafler, D. and Weiner, H. L. 1994. Regulatory T-cell clones induced by oral tolerance: suppression of autoimmune encephalomyelitis. Science 265:1237.[ISI][Medline]
-
Khoury, S. J., Hancock, W. W. and Weiner, H. L. 1992. Oral tolerance to myelin basic protein and natural recovery from experimental autoimmune encephalomyelitis are associated with downregulation of inflammatory cytokines and differential upregulation of transforming growth factor beta, interleukin 4, and prostaglandin E expression in the brain. J. Exp. Med. 176:1355.[Abstract]
-
Cash, E., Minty, A., Ferrara, P., Caput, D., Fradelizi, D. and Rott, O. 1994. Macrophage-inactivating IL-13 suppresses experimental autoimmune encephalomyelitis in rats. J. Immunol. 153:4258.[Abstract/Free Full Text]
-
Saoudi, A., Kuhn, J., Huygen, K., de, K. Y., Velu, T., Goldman, M., Druet, P. and Bellon, B. 1993. TH2 activated cells prevent experimental autoimmune uveoretinitis, a TH1-dependent autoimmune disease. Eur. J. Immunol. 23:3096.[ISI][Medline]
-
Critchfield, J. M., Racke, M. K., Zuniga, P. J., Cannella, B., Raine, C. S., Goverman, J. and Lenardo, M. J. 1994. T cell deletion in high antigen dose therapy of autoimmune encephalomyelitis. Science 263:1139.[ISI][Medline]
-
Critchfield, J. M. and Lenardo, M. J. 1995. Antigen-induced programmed T cell death as a new approach to immune therapy [review]. Clin. Immunol. Immunopathol. 75:13.[ISI][Medline]
-
Burstein, H. J. and Abbas, A. K. 1993. In vivo role of interleukin 4 in T cell tolerance induced by aqueous protein antigen. J. Exp. Med. 177:457.[Abstract]
-
Rapoport, M. J., Jaramillo, A., Zipris, D., Lazarus, A., Serreze, D. V., Leiter, E. H., Cyopick, P., Danska, J. S. and Delovitch, T. L. 1993. Interleukin-4 reverses T cell proliferative unresponsiveness and prevents the onset of diabetes in nonobese diabetic mice. J. Exp. Med. 178:87.[Abstract]
-
Liblau, R. S., Singer, S. M. and McDevitt, H. O. 1995. Th1 and Th2 CD4+ T-Cells in the pathogenesis of organ-specific autoimmune diseases. Immunol. Today 16:34.[ISI][Medline]
-
Segal, B. M., Dwyer, B. K. and Shevach, E. M. 1998. An interleukin (IL)-10/IL-12 immunoregulatory circuit controls susceptibility to autoimmune disease. J. Exp. Med. 187:537.[Abstract/Free Full Text]
-
Tian, J., Lehmann, P. and Kaufman, D. 1997. Determinant spreading of T helper cell 2 (Th2) responses to pancreatic islet autoantigens. J. Exp. Med. 186:2039.[Abstract/Free Full Text]
-
Wu, B., Deng, C., Goluszko, E. and Christadoss, P. 1997. Tolerance to a dominant T cell epitope in the acetylcholine receptor molecule induces epitope spread and suppresses murine myasthenia gravis. J. Immunol. 159:3016.[Abstract]