Search PubMed⌕ Search

Biomedical subjects

M L Cuzner

Publications and source records attributed to M L Cuzner.

At least 91 records · Page 5Linked to original sources
PubMed1987

Microglia are the major cell type expressing MHC class II in human white matter.

In normal human white matter the predominant cell type expressing MHC Class II is the microglia. This population of cells reacts with the pan macrophage marker, EBM/11, and constitutes about 13% of the glial cell population. The intensity of staining was enhanced and the absolute number of Class II+ microglia increased in normal appearing white matter from multiple sclerosis (MS) brain. As T cell activation in MS may occur in the brain the upregulation of microglia bearing MHC Class II may reflect their function as antigen presenting cells in the development of inflammatory lesions.

Adult↗
PubMed1987

Basic protein dissociating from myelin membranes at physiological ionic strength and pH is cleaved into three major fragments.

Experiments were performed with isolated human myelin membrane preparations to analyse factors that may modulate association of myelin basic protein (MBP) with the membranes and could contribute to demyelinating processes. Transfer of membranes (5 mg protein ml-1) at 37 degrees C and pH 7.4 from a hypotonic medium, in which they were relatively stable, to one of physiological ionic strength produced three major effects: (1) initial dissociation of MBP from the membranes by a nonenzymatic process that was doubled in the presence of millimolar Ca2+/Mg2+; (2) within 10 min, the appearance in the medium of three major MBP fragments (14.4, 10.3, and 8.4 kilodaltons); and (3) progressive acidification of dissociated MBP and its fragments, probably due to deamidation. Between 1 and 6 h a steady state was apparent in which protein equivalent to 15% of the MBP originally bound to the membranes was found in the medium. The three major MBP fragments formed two-thirds of this solubilised material and appeared metabolically stable for 24 h. The kinetics of peptide formation suggested that dissociated, rather than membrane-bound, MBP was cleaved by myelin-associated neutral proteases. Two-dimensional electrophoresis and immunoblotting using two monoclonal antibodies indicated that proteolysis occurred in the vicinity of residues 35 and 75. Evidence was also obtained for removal of C-terminal arginines and relatively rapid deamidation in the C-terminal half of MBP. These modifications of MBP might also occur if extracellular fluid gained access to the compacted cytoplasmic space of the myelin sheath.

Brain↗
PubMed1986

Chronic relapsing experimental autoimmune encephalomyelitis. Transient presence in blood of lymphocytes sensitised to encephalitogen at onset of inflammatory relapses.

Juvenile guinea pigs were immunised with homologous spinal cord and monitored daily over a 6-month period for neurological signs of chronic relapsing experimental autoimmune encephalomyelitis (CREAE). At various times animals were killed, numbers of leucocytes in their cerebrospinal fluid (CSF) quantified, and in vitro proliferative responses of blood lymphocytes to myelin basic protein (MBP) and its encephalitogenic nonapeptide (NP) determined. After recovering from initial acute clinical signs, animals suffered at least two major spontaneous relapses separated by remission periods of 4-5 weeks mean duration. In the early chronic phase, 5-12 weeks post-immunisation (pi), 63% of the animals recovered fully from relapses, whereas relatively irreversible neurological deficits predominated in the late chronic phase. During the acute and chronic phases, there was a highly significant correlation between clinical severity and CSF pleocytosis only in animals killed within 24 h of onset of a clinical exacerbation associated with more than 100 leucocytes/microliter of CSF. Guinea pigs with this degree of CSF pleocytosis were defined as suffering an inflammatory relapse. Blood lymphocytes responsive to MBP and NP were detected only in animals killed at the onset of clinical signs of either the acute or an inflammatory relapse. This dynamic relationship suggests that migration of encephalitogen-responsive lymphocytes via the blood to the central nervous system could produce certain relapses in CREAE. However, the relative paucity of CSF leucocytes in most animals killed during relapses between 15-26 weeks pi suggests that other factors may elicit neurological exacerbations in the late chronic phase.

Animals↗
PubMed1986

Chronic experimental autoimmune encephalomyelitis. Circulating autoantibodies bind predominantly determinants expressed by complexes of basic protein and lipids of myelin.

Chronic relapsing experimental autoimmune encephalomyelitis (CREAE) was induced by immunising juvenile strain 13 guinea pigs with homologous spinal cord tissue in adjuvant. Thirteen animals were killed in the early chronic (5-12 weeks post immunisation) and 8 in the late chronic phase (after 15 weeks pi). Plasma titres of antibodies to an isolated myelin preparation were determined by enzyme linked immunoassay. Elevated titres of these antibodies were detected between 5-26 weeks pi, varied by 10-fold between different individuals, and had no direct relationship to clinical status or time pi. Of 20 CREAE plasma with anti-myelin immunoglobulins (Igs), only 3 contained substantial amounts of antibodies to myelin lipid and these were all from animals in the late chronic phase. By contrast 15/20 of the samples contained antibodies which appeared to require lipid-protein interactions for optimal binding to antigens in isolated myelin. There was a close correlation between plasma titres of antibodies to isolated myelin and to purified myelin basic protein (MBP). Even in samples with a moderately high lipid requirement for binding to isolated myelin, purified MBP could inhibit at least 50% of the binding. These observations suggest that MBP-lipid complexes are dominant immunogens in CREAE. Gross inflammation and myelin loss in spinal cords from these CREAE guinea pigs were determined by light microscopy. Substantial inflammation was apparent in some animals between 7 and 26 weeks pi. The most severe myelin loss was observed in late chronic phase animals having plasma anti-myelin Igs with a variety of specificities. The data suggest that circulating antibodies to myelin lipids or MBP-lipid complexes could contribute to demyelination in CREAE but their titres do not correlate with the extent of this process.

Animals↗
PubMed1986

Immunocytochemical characterisation of the immune reaction in the central nervous system in multiple sclerosis. Possible role for microglia in lesion growth.

As there is evidence that in multiple sclerosis T-cell activation occurs in the central nervous system rather than outside, the inflammatory lesion may be extended through antigen presentation by cells at the edge of the plaque. In this study we present an immunocytochemical report on CNS tissue from an active case of MS, with an analysis of the distribution of CD4 and CD8 binding T cells and the expression of class I and II MHC determinants in plaques and white matter. Perivascular cuffs of early lesions, as judged by hypercellularity and minimal demyelination, contained activated T (Tac+) cells, which reacted with an anti-IL-2 monoclonal antibody. Thus sufficient T-cell growth factor would appear to be present to fuel the immune reaction in a growing lesion. The preponderance of T cells of the cytotoxic/suppressor (CD8) phenotype in the CNS parenchyma was found in conjunction with widespread staining of class I MHC antigen, a prerequisite for activity of cytotoxic T cells. Potential antigen presenting cells were demonstrated in MS plaques with a monoclonal antibody against the cytoplasmic, invariant chain of class II MHC. Macrophages and astrocytes, contributed to the staining in the hypercellular plaque border while the distribution of class II+ microglia in white matter suggest they may also be of importance in local antigen presentation.

Adult↗
PubMed1986

The production of prostaglandin and the regulation of cell division in neonate rat primary mixed glial cultures.

The production of prostaglandins has been studied in neonate rat primary mixed glial cultures. A correlation was found between inhibition of [3H]thymidine incorporation in the cultures and production of prostaglandin, which was stimulated by the addition of supernatant from Con A-activated rat splenocytes. Inhibition of prostaglandin synthesis in the cultures by indomethacin results in a striking increase in incorporation of [3H]thymidine into the cultures, an effect which was reversed by the addition of exogenous PGE2, but not PGF2 alpha. PGE was the principal prostaglandin detected, with both macrophages/microglia and astrocytes contributing to the output. A possible role for prostaglandins in the modulation of inflammatory responses in the central nervous system is discussed.

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

Expression of major histocompatibility complex antigens in neonate rat primary mixed glial cultures.

Primary mixed glial cultures containing astrocytes, oligodendrocytes and macrophages have been cultured from cerebral hemispheres of neonate rats and examined by indirect immunofluorescence for the expression of class I and II RT1 major histocompatibility complex-coded antigens. None of these cells expressed detectable levels of either class I or II antigens except for the macrophages which were weakly class I positive. Treatment with lymphokine-containing supernatant from concanavalin A-activated splenic lymphocytes resulted in increased expression of class I antigens on all cells together with the appearance of class II RT1.B and RT1.D antigens on macrophages and a small proportion of type 1/protoplasmic astrocytes. The identity of the Ia antigens was confirmed by immunoprecipitation from lysates of surface-iodinated cells. The ability of lymphokine-treated mixed glial cultures to stimulate proliferation of allogeneic lymphocytes provides additional evidence of Ia induction. A possible role for these Ia+, putative antigen-presenting cells in delayed type hypersensitivity in the central nervous system is discussed.

Animals↗
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↗
PubMed1984

Regulation of lymphocyte activation by PGE2 in multiple sclerosis.

The immunoregulatory action of prostaglandin E2 (PGE2) was examined in two independent lymphocyte activation assays of peripheral blood lymphocytes obtained from multiple sclerosis (MS) patients and normal controls. Phytohaemagglutinin (PHA)-mediated stimulation of lymphoblast transformation and leucocyte migration inhibition factor (LIF) release were both inhibited by PGE2 in a dose-dependent manner. Sixteen patients with MS were studied as a single clinical group and their PHA-stimulated lymphocytes shown to respond essentially normally to PGE2. Four patients in relapse exhibited diminished responsiveness in both assays, but only at a supraphysiological concentration of PGE2. Thus, unresponsiveness to immunoregulatory prostaglandins is unlikely to be a major contribution to the immunopathogenesis of MS.

Adult↗
PubMed1983

Distribution of nominal and latent IgG (Gm) allotypes in plaques of multiple sclerosis brain.

Concentrations of IgG allotypes G1m(1), G1m(3) and G3m(11) in neutral pH eluates from discrete plaques of multiple sclerosis (MS) brain and from white matter of control brain were determined to obtain information about distribution of B cell clones among MS lesions. Within each MS brain a predominant nominal IgG1 allotype was distributed rather homogeneously in all plaques while quantitatively minor allotypes showed some fluctuation. Latent IgG1 allotypes were detected (7-12% of the corresponding nominal allotype level) in some tissue eluates from both MS and control brains, which were homozygous for either G1m(1) or G1m(3). By contrast, the expression of a latent IgG3 allotype, namely G3m(11), was apparently MS restricted. Large amounts of latent allotypes were detected only in recent plaques with lymphoid cells whereas the distribution of total plaque associated IgGs did not correlate with the presence of lymphoid cells. Latent allotypes in recent MS lesions may mark a transient immunological activity which coincides with the infiltration of lymphoid cells and precedes the appearance in these plaques of oligoclonal IgGs, the distribution of which may parallel that of the predominant nominal allotypes.

Adult↗
PubMed1982

Rapid analysis of immunoglobulin isoelectric focusing patterns with cellulose nitrate sheets and immunoperoxidase staining.

Immunoglobulins which have been focused to their isoelectric points in thin-layer polyacrylamide gels can be transferred by diffusion to the surface of cellulose nitrate sheets with retention of the original focusing patterns. IgG can be detected with peroxidase-linked antiserum. Unlike polyacrylamide gel, cellulose nitrate offers no permeability barrier, and so washing times are reduced from days to minutes. Thus small quantities (less than 1 microgram) of IgG may be visualized within 24 h of isoelectric focusing. In addition after immobilization on cellulose nitrate, immunoglobulin reactivity with antigens, including those of high molecular weight, may be analysed.

Animals↗
PubMed1982

Immunosuppression by cyclosporin A of experimental allergic encephalomyelitis.

Cyclosporin A (CsA), an immunosuppressant which acts selectively on antigen-responding T cells, was tried in the treatment of experimental allergic encephalomyelitis (EAE). The drug was highly effective in preventing the appearance of clinical and pathological signs of EAE in rats, guinea pigs and monkeys. Treatment of the established disease also reduced the incidence and severity of symptoms, and significantly reduced the number of inflammatory lesions in the central nervous system.

Animals↗
PubMed1982

The effect of cyclosporin A on the adoptive transfer of experimental allergic encephalomyelitis in the Lewis rat.

Experimental allergic encephalomyelitis (EAE) can be adoptively transferred in Lewis rats with spleen cells from immunized animals, after culture with concanavalin A or myelin basic protein (MBP). The effect of the immunosuppressive drug cyclosporin A (CsA) on the in vitro and in vivo steps of the cell transfer has been investigated. Clinical signs of EAE were completely suppressed by CsA in rats immunized with MBP in Freund's complete adjuvant and spleen cells from these animals, cultured with the antigen, did not transfer the disease. The incidence of transferred disease was also reduced, if recipients were treated with CsA, although a higher dose of drug than that needed to suppress active EAE was required. In both instances complete suppression of EAE was only accomplished for the period of dosing, although the clinical signs of disease which appeared after withdrawal of the drug were significantly reduced in severity. These results imply that an immune response in the host animal is a prerequisite for adoptive transfer of EAE or suggest that CsA can regulate the action of lymphocytes already primed.

Animals↗
PubMed1982

Analysis of immunoglobulin G in multiple sclerosis brain: quantitative and isoelectric focusing studies.

Immunoglobulin G (IgG) in soluble and particulate fractions of discrete tissue samples from multiple sclerosis (MS) brain was analysed. Supernatant IgG/albumin rations and particulate-bound IgG levels were highest in samples dissected from MS plaques and adjacent white matter. Acid extracts of particulate fractions from the equivalent of 1 g of MS plaque tissue contained up to 15 micrograms IgG, an order of magnitude less than the amount in extracts from a subacute sclerosing panencephatitis (SSPE) brain, but 20 times more than those from control brain. By contrast, supernatant fractions from SSPE brain and some MS plaques contained comparable amounts (100-200 micrograms/g tissue) of IgG, which were 10 times greater than those from control brain. Samples were subjected to isoelectric focusing (IEF), and IgG was visualized by immunoperoxidase staining. The IEF patterns of IgG from control samples were diffuse but samples from demyelinated MS tissue displayed distinct oligoclonal bands of IgG. A number of common IgG bands were apparent in extracts of supernatant and particulate fractions from the same plaque. The IEF spectra of plaque samples from three MS brains were different. Furthermore, quantitative variations in certain IgG bands were observed in different plaques from the same brain.

Adult↗