Biomedical subjects

J Newcombe

Publications and source records attributed to J Newcombe.

At least 19 recordsLinked to original sources

PubMed1992

Gamma delta T-cell receptor repertoire in acute multiple sclerosis lesions.

Gamma delta T cells are a distinct lymphocyte population that can exhibit reactivity with heat shock proteins over-expressed at inflammatory sites. As gamma delta T cells may be involved in the central nervous system (CNS) inflammatory process in multiple sclerosis (MS), we examined T-cell populations in MS plaque tissue by quantitative immunohistochemistry and sequence analysis of T-cell antigen receptor (TCR) delta chains. Gamma delta T cells that express the variable (V) gene segments V delta 1, V delta 2, and V gamma 2 (V gamma 9) were found to accumulate in acute, demyelinating MS plaques and appeared to have undergone clonal expansion, most likely because of recognition of a specific CNS ligand. Further, 60-kDa and 90-kDa heat shock proteins (hsp60 and hsp90), which may be target antigens for autoreactive gamma delta T cells, were found to be expressed in normal CNS tissue and overexpressed in acute MS plaques. In acute plaques, hsp60 was found in foamy macrophages, while hsp90 was detected in reactive astrocytes. These results provide evidence for a role of gamma delta T cells in active stages of MS.

Base Sequence↗

PubMed1992

T cell receptor V alpha-V beta repertoire and cytokine gene expression in active multiple sclerosis lesions.

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system with presumed autoimmune etiology. A recent study has suggested the presence of a restricted T cell receptor (TCR) V alpha repertoire in MS lesions. The presence of such a restricted TCR repertoire at the site of inflammation would have important consequences for the pathogenesis and the ultimate treatment of MS. To further characterize the TCR V alpha and V beta repertoire in MS plaque tissue, we examined a series of 26 histologically well-characterized central nervous system (CNS) tissue specimens from six MS patients as well as samples from five normal postmortem cases and a case of subacute sclerosing panencephalitis. RNA was extracted from frozen sections and cDNAs were amplified by polymerase chain reaction using primers for TCR V alpha (V alpha 1-18) and V beta (V beta 1-19) gene families. This analysis demonstrated a broad TCR V alpha-V beta repertoire in active lesions, while fewer TCR V genes were detected in chronic plaques and control samples. Even though a large number of TCR V alpha and V beta gene segments were present in the majority of active lesions, there were clear differences in the TCR repertoire between plaques from the same case, suggesting that local events influence the TCR repertoire at the level of T cell recruitment or T cell expansion. Examination of cytokine mRNAs demonstrated that IL-1 mRNA was present in the majority of acute and subacute plaques, while IL-2 and IL-4 mRNA were detected in only a few acute lesions. These data demonstrate that the TCR repertoire in MS plaques is polyclonal. However, autoreactive alpha/beta T cells thought to be critical in the initiation of the inflammatory process probably represent a minor fraction of T cells in active MS plaques and may use a limited number of TCR V gene segments for recognition of the autoantigen.

Acute Disease↗

PubMed1992

Monoclonal antibody 14E recognizes an antigen common to human oligodendrocytes, Schwann cells, Bergmann glia, and a subpopulation of reactive glia.

The monoclonal antibody 14E immunocytochemically stains the nuclear membrane of oligodendrocytes but not myelin in tissue sections of adult normal human white matter. The nuclear membranes of Schwann cells in human peripheral nerve and cerebellar Bergmann glia were also visualized with this antibody. In actively demyelinating multiple sclerosis plaques the 14E antibody stained increased numbers of oligodendrocytes and the nuclei, perikarya and cell processes of hypertrophic glia, which were often multinucleate. Scattered small groups of these hypertrophic glia were present in areas of dense astrogliosis in acute plaques. The 14E-positive hypertrophic cells could be either a subpopulation of reactive astrocytes or bipotential glial precursors.

Antibodies, Monoclonal↗

PubMed1992

Lipocortins (annexins) 1, 2, 4 and 5 are increased in the central nervous system in multiple sclerosis.

Western blotting and densitometry have been used to investigate the lipocortin content of post-mortem central nervous system (CNS) tissue samples from multiple sclerosis (MS) patients and normal controls. Lipocortins 1, 2, 4 and 5 were all detected in normal control grey and white matter. In white matter samples from MS patients these lipocortins were found to be significantly increased, a further elevation in lipocortin content was observed in MS plaque tissue. The implications of these findings with respect to the role of these proteins in inflammatory CNS disease and a possible mechanism of steroid action in the therapy of MS are discussed.

Adult↗

PubMed1992

Measurement of low-molecular-weight antioxidants, uric acid, tyrosine and tryptophan in plaques and white matter from patients with multiple sclerosis.

The levels of the antioxidants ascorbic acid, cysteine, reduced glutathione and alpha-tocopherol, of the free-radical marker uric acid and of the amino acids tyrosine and tryptophan were measured by means of high-pressure liquid chromatography in plaques, adjacent white matter and distant white matter from patients with multiple sclerosis, and in central nervous system tissue from patients without neurological diseases. Cholesterol and DNA were also determined, to check demyelination and cellularity. Uric acid was increased and glutathione correspondingly decreased in plaques; alpha-tocopherol was lowest in plaques and highest in distant white matter in all cases. Ascorbic acid, cysteine, tyrosine and tryptophan were not significantly changed in any tissue. The results provide evidence supporting the involvement of free radicals in multiple sclerosis.

Adult↗

PubMed1991

Histopathology of multiple sclerosis lesions detected by magnetic resonance imaging in unfixed postmortem central nervous system tissue.

Postmortem unfixed whole brains from 17 multiple sclerosis and 6 control cases were examined by magnetic resonance imaging (MRI) using a T2-weighted spin echo sequence and histology to determine the relationship between areas of abnormal MRI signal and underlying pathological change. In group 1, small MRI lesions and correspondingly small plaques, most of which were chronic, were detected histologically in 5 brains. In 4 brains there were more extensive areas of both abnormal signal and histological plaques which were more often active (group 2). However, in a further 5 brains extensive MRI abnormalities were observed when only small periventricular plaques were present histologically (group 3). Lesions in the hindbrain and cerebral grey matter were infrequently observed by MRI. The extensive MRI abnormalities seen in areas in which only small histological plaques were found may be the result of vascular permeability changes in the normal-appearing white matter surrounding plaques.

Autopsy↗

PubMed1991

Expression of the 14E antigen in glial cells in human normal and pathological central nervous system tissues.

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Antibodies, Monoclonal↗

PubMed1990

Spleen versus CNS immunoglobulin G in multiple sclerosis: an isoelectric focusing study.

Immunoglobulin G (IgG) band patterns were investigated in a peripheral immune compartment, the spleen, and the central nervous system (CNS) compartment in 6 multiple sclerosis (MS) subjects and 3 controls in a search for systemic humoral immune response that may be related to the localized immune response seen in MS. Using the isoelectric focusing (IEF) technique with immunoperoxidase staining of proteins transferred to nitrocellulose membranes, we were not able to demonstrate any qualitative abnormalities of spleen or serum IgG in the MS cases, whilst all matched CNS tissues and CSF specimens were clearly positive for oligoclonal IgG bands. Our results suggest that there is no systemic oligoclonal IgG secretion in MS. This further supports the presence of a compartmentalized IgG intrathecal immune response in MS and emphasizes the organ specificity of MS.

Central Nervous System↗

PubMed1988

Monoclonal antibody 14E identifies the oligodendrocyte cell body in normal adult human and rat white matter.

A monoclonal antibody, 14E, which detects immunocytochemically the perikarya of interfascicular oligodendrocytes in sections of normal adult human and rat white matter, was obtained using isolated normal human oligodendrocytes as the immunogen. 14E is an IgM antibody that reacts with a polypeptide of approximate molecular weight 23,000 on immunoblots of the particulate fraction of normal white matter. In sections of active multiple sclerosis plaques and recent infarcts, 14E immunostained the cell bodies and processes of only a small number of hypertrophic glial cells which could be oligodendrocytes undergoing pathological changes or a subpopulation of reactive astrocytes.

Animals↗

PubMed1988

A new epitope on human myelin basic protein arising from cleavage by a metalloendoprotease associated with brain myelin membranes.

Human brain myelin membranes were incubated to allow activity of an associated metalloendoprotease which cleaves myelin basic protein (MBP). A 10.3 kDa C-terminal fragment of MBP, peptide C, isolated from the incubation medium had a blocked N-terminal. After treatment with pyroglutamyl aminopeptidase, N-terminal sequencing indicated that Gln74 of MBP formed the N-terminal residue of peptide C. A rabbit antiserum was raised to a synthetic peptide containing the sequence Pyroglu-Lys-Ser-His-Gly-Arg, corresponding to the first six residues of peptide C. By immunoblotting this serum reacted with peptide C but not with intact MBP. The data indicate that cleavage of MBP by a myelin-associated protease engenders a new epitope.

Amino Acid Sequence↗

PubMed1988

The nature of inflammatory components during demyelination in multiple sclerosis.

Immune reactivity in the central nervous system (CNS) in multiple sclerosis (MS) can be fuelled by activated T lymphocytes sequestered in the brain and those entering systemically. The perivascular cuff of the inflammatory lesion consists predominantly of T cells and macrophages, while the hypercellular interface between normal and degenerating myelin is comprised mainly of macrophages and activated microglia. MHC class II+ cells are abundant in the hypercellular zone and expression of both the polymorphic and invariant chains of the molecule are expressed beyond the plaque edge in the white matter where the staining is restricted largely to microglia. Under carefully controlled staining conditions expression of MHC class II can be demonstrated on microglia in control white matter. Thus the immunological privilege of the CNS does not appear to preclude constitutive expression of MHC antigens or prevent the traffic of activated lymphocytes into the brain parenchyma. However, the antigens priming the immune reaction in the CNS in MS and the role of antibodies in the demyelinating process remain a matter for speculation and the exact mechanisms of demyelination are as yet unresolved.

Animals↗

PubMed1986

Distribution of glial fibrillary acidic protein in gliosed human white matter.

Glial fibrillary acidic protein (GFAP) in gliosed white matter from multiple sclerosis plaques and cerebral infarcts was examined by polyacrylamide gel electrophoresis and immunoblotting. Using a monoclonal antibody raised against human GFAP, up to 11 GFAP polypeptide bands of molecular weight 37-49 kilodaltons were identified in particulate and supernatant fractions of CNS tissue homogenates. Soluble GFAP constituted about one-quarter of the total GFAP in normal cerebral white matter. In brain lesions in which reactive astrocytes were observed microscopically, the proportion of soluble GFAP was increased, with a greater representation of the lower-molecular-weight forms. In brain chronic sclerotic plaques, almost all of the GFAP was in the particulate form. Purified particulate GFAP was susceptible to proteolysis at acid but not at neutral pH in the presence of CNS homogenates. In tissue autolysis studies, GFAP was stable in situ for periods well in excess of average CNS postmortem times.

Astrocytes↗

PubMed1985

Serum antibodies against central nervous system proteins in human demyelinating disease.

An immunoblotting technique has been used to screen serum samples from patients with demyelinating disease for antibody directed against central nervous system proteins. Antibodies of the IgM, IgG and IgA class directed against one or more of the particulate fraction proteins tubulin, myelin basic protein, 69 K neurofilament protein, glial fibrillary acidic protein, myelin associated glycoprotein or Wolfgram protein were present in 94, 54 and 47%, respectively, of multiple sclerosis sera examined. IgM antibodies against tubulin and myelin basic protein predominated. A similar antibody spectrum was seen in a significant proportion of sera from patients with optic neuritis, subacute sclerosing panencephalitis and motor neurone disease, in which primary or secondary demyelination occurs. Antibodies of all three classes directed against the 169 K and 220 K neurofilament proteins and against some unidentified proteins of human peripheral nerve, kidney, liver, spleen and skeletal muscle were detected in sera from healthy subjects and patients with neurological disease.

Adolescent↗

PubMed1982