Biomedical subjects

V K Tuohy

Publications and source records attributed to V K Tuohy.

7 recordsLinked to original sources

PubMed1992

Monocytes in active multiple sclerosis: intact regulation of HLA-DR density in vitro despite decreased HLA-DR density in vivo.

HLA-DR expression on circulating monocytes varies as a function of disease activity in patients with multiple sclerosis (MS), a putative immunopathological demyelinating disorder. Specifically, monocytes isolated from subjects with active MS exhibit reduced HLA-DR antigen density, and immunoregulatory aberrations such as impaired T lymphocyte-mediated suppression correlate strongly with this quantitative defect. To address the mechanism underlying this phenomenon, we compared in vitro regulation of HLA-DR by interferon beta (IFN beta), interferon gamma (IFN gamma), and lipopolysaccharide (LPS) in monocytes from patients with stable and active MS and normal individuals. Interferon-gamma and LPS enhanced monocyte expression of HLA-DR equally in both MS patient groups, suggesting that underexpression of HLA-DR in active MS was not explained by impaired in vivo monocyte responsiveness. Furthermore, interferon regulation of HLA-DR in normals and stable MS subjects was indistinguishable, indicating that aberrant interferon-mediated regulation of class II major histocompatibility complex (MHC) on circulating monocytes does not appear to be a characteristic of the MS disease state.

HLA-DR Antigens↗

PubMed1992

Myelin proteolipid protein: minimum sequence requirements for active induction of autoimmune encephalomyelitis in SWR/J and SJL/J mice.

Proteolipid protein (PLP) is the major protein constituent of mammalian central nervous system myelin. We have previously identified two different PLP encephalitogenic T cell epitopes in two mouse strains. Murine PLP peptides 103-116 YKTTICGKGLSATV and 139-151 HCLGKWLGHPDKF are encephalitogenic determinants in SWR/J (H-2q) and SJL/J (H-2s) mice, respectively. The purpose of the present study was to determine the minimum sequence requirements for each of these PLP encephalitogens. In SWR/J mice, at least two distinct overlapping peptides can induce experimental autoimmune encephalomyelitis (EAE). The eleven residue sequences PLP 105-115 TTICGKGLSAT and PLP 106-116 TICGKGLSATV are encephalitogenic in SWR/J mice, but PLP 106-115 TICGKGLSAT, the decapeptide indigenous to both sequences, is non-encephalitogenic. In contrast, the shortest PLP sequence capable of inducing EAE in SJL/J mice is the nonapeptide 141-149 LGKWLGHPD. These data indicate that encephalitogenic determinants of PLP are short contiguous peptide sequences similar in length and diversity to those of MBP.

Amino Acid Sequence↗

PubMed1991

Parental MHC molecule haplotype expression in (SJL/J x SWR)F1 mice with acute experimental allergic encephalomyelitis induced with two different synthetic peptides of myelin proteolipid protein.

To determine if the Ag that induces an autoimmune disease influences parental MHC haplotype molecule expression in situ in MHC heterozygotes, acute experimental allergic encephalomyelitis (EAE) was induced with different encephalitogenic peptides in (SJL/J x SWR)F1 mice. The mice were sensitized with either a synthetic peptide corresponding to mouse myelin proteolipid protein (PLP) residues 103-116 YKTTICGKGLSATV which induces EAE in SWR (H-2q), but not SJL/J (H-2s) mice or a synthetic peptide corresponding to PLP residues 139-151 HCLGKWLGHPDKF which is encephalitogenic in SJL/J but not SWR mice. Mice were killed when they were moribund or at 30 days after sensitization. Twelve of 18 F1 mice given PLP peptide 103-116 and 12 of 17 mice given PLP peptide 139-151 developed EAE within 2 to 3 wk after sensitization. Cryostat sections of brain samples from F1 and parental mice were immunostained with a panel of mAb identifying H-2s and H-2q class I and II MHC molecules. In brains of controls, class I MHC molecules were expressed on choroid plexus, endothelial cells, and microglia whereas class II MHC molecules were absent. In EAE lesions, class I and II MHC molecules were present on inflammatory and parenchymal cells, but the degree of parental haplotype molecule expression did not vary with the different peptide Ag tested. Thus, in (SJL/J x SWR)F1 mice, myelin PLP peptides 103-116 and 139-151 are co-dominant Ag with respect to clinical and histologic disease and parental haplotype MHC molecule expression. We propose a unifying hypothesis consistent with these results and previous observations of differential Ia expression in (responder x non-responder)F1 guinea pigs. We suggest that MHC molecules may bind locally derived peptide Ag in inflammatory sites and that these interactions influence levels of MHC haplotype molecules on APC.

Amino Acid Sequence↗

PubMed1991

Sensitive competitive-binding ELISAs for quantifying free kappa and lambda light chains in cerebrospinal fluid.

Simple, sensitive, and fully standardized solid-phase enzyme-linked competitive binding immunoassays to quantify free kappa and lambda immunoglobulin light chains are described. The assays were developed to measure the concentration of free light chains in cerebrospinal fluid (CSF), in part because elevated levels of free kappa light chains have utility as a diagnostic marker for multiple sclerosis (MS). Polyclonal rabbit antibodies raised against pooled Bence Jones proteins are bound to solid-phase Staphylococcal protein A and used as the primary antisera in this assay. A pool of Bence Jones proteins isolated from the urine of 10 individuals with multiple myeloma are used as a biotin-labeled ligand and to develop a standard curve. The assays as described are sensitive to the low nanogram range and are specific for free kappa or lambda light chains. The assays were found to have acceptable precision, and results correlated highly with concentrations determined using competitive-binding radioimmunoassays previously described.

Binding, Competitive↗

PubMed1990

Inhibition of murine relapsing experimental autoimmune encephalomyelitis by immune tolerance to proteolipid protein and its encephalitogenic peptides.

Tolerization of SJL/J mice with splenocytes coupled with proteolipid protein (PLP), the major protein component of central nervous system myelin, resulted in dramatic inhibition of relapsing experimental autoimmune encephalomyelitis (R-EAE) induced by mouse spinal cord homogenate (MSCH). Mice tolerized with splenocytes coupled with MSCH (a complex mixture of neuroantigens) or with purified PLP, but not purified myelin basic protein, were resistant to the development of clinical and histologic R-EAE. In addition, mice rendered tolerant to an encephalitogenic peptide of PLP were significantly protected, whereas mice tolerized to a nonencephalitogenic peptide of PLP were highly susceptible, to the induction of MSCH-induced R-EAE. Thus, immune responses directed against encephalitogenic regions of PLP appear to play a major role in the development of R-EAE induced by MSCH in SJL/J mice. These results also indicate that determinant-specific immune tolerance is a feasible approach to the regulation of a disease that involves autoimmune responses to a variety of Ag.

Animals↗

PubMed1990

Class II-restricted T cell responses in Theiler's murine encephalomyelitis virus (TMEV)-induced demyelinating disease. III. Failure of neuroantigen-specific immune tolerance to affect the clinical course of demyelination.

Intracerebral inoculation of Theiler's murine encephalomyelitis virus (TMEV) into susceptible mouse strains produces a chronic demyelinating disease in which mononuclear cell-rich infiltrates in the central nervous system (CNS) are prominent. Current evidence strongly supports an immune-mediated basis for myelin breakdown, with an effector role proposed for TMEV-specific, major histocompatibility complex (MHC) class II-restricted delayed-type hypersensitivity (DTH) responses in which lymphokine-activated macrophages mediate bystander demyelination. The present study examined the possibility that concomitant or later-appearing neuroantigen-specific autoimmune T cell responses, such as those demonstrated in chronic-relapsing experimental allergic encephalomyelitis (R-EAE), may contribute to the demyelinating process following TMEV infection. T cell responses against intact, purified major myelin proteins (myelin basic protein (MBP) and proteolipid protein (PLP], and against altered myelin constituents were readily demonstrable in SJL/J mice with R-EAE, but were not detectable in SJL/J mice with TMEV-induced demyelinating disease. TMEV-infected mice also did not display T cell responses against the peptide fragments of MBP(91-104) and PLP(139-151) recently shown to be encephalitogenic in SJL/J mice. In addition, induction of neuroantigen-specific tolerance to a heterogeneous mixture of CNS antigens, via the i.v. injection of syngeneic SJL/J splenocytes covalently coupled with mouse spinal cord homogenate, resulted in significant suppression of clinical and histologic signs of R-EAE and the accompanying MBP- and PLP-specific DTH responses. In contrast, neuroantigen-specific tolerance failed to alter the development of clinical and histologic signs of TMEV-induced demyelinating disease or the accompanying virus-specific DTH and humoral immune responses. These findings demonstrate that TMEV-induced demyelinating disease can occur in the apparent absence of neuroantigen-specific autoimmune responses. The relationship of the present results to the immunopathology of multiple sclerosis is discussed.

Animals↗

PubMed1990

Acute experimental allergic encephalomyelitis in SJL/J mice induced by a synthetic peptide of myelin proteolipid protein.

Clinical, histologic, and ultrastructural characteristics of acute experimental allergic encephalomyelitis (EAE) induced by sensitization with a synthetic peptide corresponding to mouse myelin proteolipid protein (PLP) residues 139-151 HCLGKWLGHPDKF were studied in SJL/J mice. Groups of mice were immunized with 20, 50, or 100 nmol of the peptide and were killed from seven to 28 days after sensitization or when they were moribund. Beginning on Day 9, the mice showed signs of EAE and the disease progressed rapidly to paralysis. Central nervous system (CNS) inflammation, edema, gliosis, and demyelination were found in all mice killed between Days 10 and 28 and white matter lesion areas correlated with clinical score at the time the mice were killed. Peripheral nerve roots and the cauda equina did not have lesions. Within the range studied, the severity of clinical or histologic disease was the same regardless of the PLP peptide dose. Two of ten mice immunized with 100 nmol and none of 14 mice given smaller doses of a synthetic peptide of mouse myelin basic protein (MBP) showed clinical EAE. These mice had small numbers of CNS lesions that were indistinguishable from those in PLP peptide-sensitized mice. These findings demonstrate that immunization of SJL/J mice with PLP peptide 139-151 produces a disease with the clinical and morphologic features of CNS tissue-, whole PLP-, whole MBP-, and MBP peptide-induced acute EAE. Thus, PLP is a major encephalitogen and immune reactions to epitopes of different myelin proteins may induce identical patterns of injury in the CNS.

Acute Disease↗