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Biomedical subjects

L Steinman

Publications and source records attributed to L Steinman.

At least 73 records · Page 4Linked to original sources
PubMed1997

Myoblast implantation in Duchenne muscular dystrophy: the San Francisco study.

We evaluated myoblast implantation in 10 boys with Duchenne muscular dystrophy (DMD) and absent dystrophin (age 5-10 years) who were implanted with 100 million myoblasts in the anterior tibial muscle of one leg and placebo in the other. Cyclosporine (5 mg/kg/day) was administered for 7 months. Pre- and postimplantation (after 1 and 6 months) muscle biopsies were analyzed. Force generation (tetanic tension and maximum voluntary contraction) was measured monthly in a double-blind design. There was increased force generation in both legs of all boys, probably due to cyclosporine. Using the polymerase chain reaction, evidence of myoblast survival and dystrophin mRNA expression was obtained in 3 patients after 1 month and in 1 patient after 6 months. These studies suggest a salutary effect of cyclosporine upon muscular force generation in Duchenne muscular dystrophy; however, myoblast implantation was not effective in replacing clinically significant amounts of dystrophin in DMD muscle.

Adult↗
PubMed1997

Multiple sclerosis: a polygenic disease involving epistatic interactions, germline rearrangements and environmental effects.

Several regions of the human genome are associated with susceptibility to multiple sclerosis (MS). We review studies of linkage of MS to germline genes using microsatellites. A modest effect on susceptibility was seen with markers in the vicinity of 6p21 (HLA) and 17q22. The influence of epistatic interactions between these genes is considered. The impact of genetic rearrangements of certain germline genes on susceptibility to MS is described. Analysis of TCR gene rearrangements has established some of the target antigens of the immune response in MS. Environmental influences on MS are described with particular attention given to how microbes might trigger demyelinating disease.

Autoimmunity↗
PubMed1997

Amelioration of relapsing experimental autoimmune encephalomyelitis with altered myelin basic protein peptides involves different cellular mechanisms.

T-cells specific for a region of human myelin basic protein, amino acids 87-99 (hMBP87-99), have been implicated in the development of multiple sclerosis (MS) a demyelinating disease of the central nervous system. Administration of soluble altered peptide ligand (APL), made by substituting native residues with alanine at either positions 91(91K > A or A91) or 97 (97R > A or A97) in the hMBP87-99 peptide, blocked the development of chronic relapsing experimental autoimmune encephalomyelitis (R-EAE), in the SJL mouse. The non-encephalitogenic APL A91, appears to induce cytokine shifts from Th1 to Th2 in the target T-cells, whereas the encephalitogenic superagonist APL A97 causes deletion of the MBP87-99 responsive cells. Thus, single amino acid changes at different positions in the same peptide epitope can lead to APL capable of controlling auto-immune disease by different mechanisms.

Animals↗
PubMed1997

CD4+ T-cell subsets in autoimmunity.

The discovery that functionally heterogeneous CD4+ T-cell subsets secrete different cytokines offers an explanation for the ability of certain T cells to mediate a predominant cell-mediated immune response versus a humoral response often accompanied by allergic manifestations. Th1 cells, important for cell-mediated immunity by their production of IL-2, IFN-gamma and lymphotoxin, have been implicated in the immunopathology of certain organ-specific autoimmune diseases whereas a role as regulators has been suggested for IL-4 and IL-10 producing Th2 cells. Recent findings, however, beg re-evaluation of the direct role of Th2 cells in the induction or maintenance of tolerance, whereas evidence for the role of a distinct subset of regulatory T cells producing TGF-beta to suppress cell-mediated immunopathology is compelling.

Animals↗
PubMed1997

Perivascular T cells express the pro-inflammatory chemokine RANTES mRNA in multiple sclerosis lesions.

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system (CNS), characterized by accumulation of mononuclear cells. The pathogenesis of MS is complex and probably involves soluble immune mediators, particularly cytokines, and activated memory T cells, that are thought to migrate into the CNS. During lesion formation in MS, cytokines regulate cell functions, such as cell recruitment and migration. Because the chemokine RANTES play a role in both activating and recruiting leucocytes, particularly memory T cells into inflammatory sites, the authors have assessed RANTES mRNA levels at the site of lesions. Expression levels were analysed in brain samples and compared with neurological, infectious and other controls. RANTES was expressed by activated perivascular memory T cells, predominantly located at the edge of active plaques. While RANTES mRNA was detected in all 17 MS brains analysed, it was only found in six of the 14 control patients and generally at a lower expression level. In view of the regulatory and chemotactic properties of RANTES, these results imply that RANTES in MS lesions may play an important role in the activation and/or selective accumulation of memory T cells and, thereby, in the pathogenic events associated with MS.

Adult↗
PubMed1997

Experimental autoimmune encephalomyelitis in IL-4-deficient mice.

Experimental autoimmune encephalomyelitis (EAE) in an inflammatory demyelinating disease which usually follows a monophasic course. Autoreactive Th1 CD4+ T cells are responsible for the lesions, whereas autoreactive Th2 CD4+ T cells can, upon adoptive transfer, suppress the disease process. However, the role of IL-4 and Th2 cells in the spontaneous remission of EAE and in the prevention of relapses is not known. We have addressed these issues using IL-4-deficient mice in which the differentiation of Th2 CD4+ T cells is severely compromised. The clinical course of actively induced EAE was compared in IL-4+/+, IL-4+ /- and IL-4-/- mice on the PL/J genetic background. No significant differences were noted between groups for the frequency, severity and duration of EAE, and the frequency of relapses. Our results indicate that IL-4, despite its well-documented regulatory role in EAE, is not necessary for the spontaneous remission of disease or for the prevention of relapses. Therefore, in the absence of IL-4, overlapping or compensatory immunoregulatory mechanisms can restrict an inflammatory response within the central nervous system.

Animals↗
PubMed1996

IL-2 and TNF receptors as targets of regulatory T-T interactions: isolation and characterization of cytokine receptor-reactive T cell lines in the Lewis rat.

T cells are considered to be of prime importance in immune regulation of both B and T cell functions. The targets of recognition in T-T cell interactions are not clear. Most recent experimental work has focused on the idiotypic regulatory interactions mediated by TCR peptides. There is experimental evidence that regulatory cells exist that do not recognize the TCR. This type of regulation is selectively induced by activated T cells. Therefore, we designed this study to examine the possible role of cytokine receptors as targets of immune regulation. We tested two peptides of IL-2R alpha-chain, 2 of IL-2R beta-chain, and one of TNFR (p60). All peptides were found to be immunogenic at inducing T cell proliferation and four induced Abs in Lewis rats. We generated T cell lines to these five peptides, and tested them both in vitro and in vivo. We found that the T cells exhibited a proliferative response when cultured with activated, irradiated stimulator cells that were augmented upon addition of the cytokine receptor peptide. The cytokine profile of the lines was characterized as well as the Vbeta gene composition. One of the lines significantly protected against active encephalomyelitis. These results point at cytokine receptors as possible targets of immune regulation and T-T cell interactions.

Amino Acid Sequence↗
PubMed1996

Multiple sclerosis: from a myelin point of view.

Multiple sclerosis (MS) is a demyelinating disease during which an autoimmune reaction is directed against oligodendrocytes. Alterations of normal myelin structure or oligodendrocyte metabolism may be primary events that influence the susceptibility to MS. Once triggered, the immune system attacks and destroys myelin and the myelin forming cell. Evidence is presented that the oligodendrocyte responds to the attack by immune cells and their secreted products through modulation of its metabolism and gene expression. Cytokines, immunoglobulins, and complement complexes may elicit a survival response in the oligodendrocytes, involving the induction of heat shock proteins and other protective molecules. The possibility of manipulating these complex glial cell functions and controlling their pathologic interactions with immune cells will illuminate how myelin damage can be contained and how the injured tissue can be repaired.

Autoimmune Diseases↗
PubMed1996

A few autoreactive cells in an autoimmune infiltrate control a vast population of nonspecific cells: a tale of smart bombs and the infantry.

Inflammatory infiltrates in tissue-specific autoimmune disease comprise a collection of T cells with specificity for an antigen in the target organ. These specific cells recruit a population of nonspecific T cells and macrophages. The rare tissue-specific T cells in the infiltrate have the capacity to regulate both the influx and the efflux of cells from the tissue. Administration of an altered peptide ligand for the specific T cell which triggers autoimmunity can lead to the regression of the entire inflammatory ensemble in a few hours. Interleukin 4 is a critical cytokine involved in the regression of the inflammatory infiltrate.

Animals↗
PubMed1996

Treatment of experimental encephalomyelitis with a peptide analogue of myelin basic protein.

Following induction of experimental encephalomyelitis with a T-cell clone, L10C1, that is specific for the myelin basic protein epitope p87-99, the inflammatory infiltrate in the central nervous system contains a diverse collection of T cells with heterogeneous receptors. We show here that when clone L10C1 is tolerized in vivo with an analogue of p87-99, established paralysis is reversed, inflammatory infiltrates regress, and the heterogeneous T-cell infiltrate disappears from the brain, with only the T-cell clones that incited disease remaining in the original lesions. We found that antibody raised against interleukin-4 reversed the tolerance induced by the altered peptide ligand. Treatment with this altered peptide ligand selectively silences pathogenic T cells and actively signals for the efflux of other T cells recruited to the site of disease as a result of the production of interleukin-4 and the reduction of tumour-necrosis factor-alpha in the lesion.

Amino Acid Sequence↗
PubMed1996

Mice with a disrupted IFN-gamma gene are susceptible to the induction of experimental autoimmune encephalomyelitis (EAE).

Experimental autoimmune encephalomyelitis (EAE), an animal model for multiple sclerosis, is an autoimmune disorder seen in mice and rats following immunization with myelin basic protein (MBP) or MBP-derived peptides. IFN-gamma, a cytokine produced by a variety of cells, is involved in many inflammatory and immune regulatory events. Contradictory results concerning exacerbations and the disease course were seen comparing injections of IFN-gamma in humans suffering from multiple sclerosis to studies using anti-IFN-gamma Abs in mice with EAE. To study the role of IFN-gamma and IFN-gamma-producing cells in EAE, we crossed IFN-gamma knockout mice (H-2b) (unable to produce IFN-gamma due to the disruption of the IFN-gamma gene) with an EAE-susceptible mouse strain, B10.PL (H-2u). EAE was seen in IFN-gamma knockout mice, heterozygotic (IFN-gamma +/-) mice, as well as wild-type littermates following immunization with MBP. Histologic analyses of the central nervous system of IFN-gamma knockout mice with EAE revealed massive infiltrates composed of lymphocytes, macrophages, and granulocytes. We conclude that the presence of IFN-gamma is not crucial to the induction or the clinical course of EAE.

Animals↗
PubMed1996

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.

Amino Acid Sequence↗
PubMed1996

Isolation and Characterization of Autoreactive T Cells in Experimental Autoimmune Encephalomyelitis of the Mouse

Experimental autoimmune encephalomyelitis (EAE) can be adoptively transferred by T cells that are specific for autoantigens of the central nervous system. A variety of autoantigens and their derived peptides have been shown to be excellent stimulators for encephalitogenic T-cell lines and clones. This article describes protocols for the establishment and characterization of autoreactive T-cell lines and clones and for the study of EAE induced by these cells. The rationale for using transferred EAE models is discussed, together with advantages and disadvantages of using in vitro cultured T cells compared with Freund's adjuvant-based immunization for the induction of EAE.

Journal Article↗