Biomedical subjects

V Dodelet

Publications and source records attributed to V Dodelet.

5 recordsLinked to original sources

PubMed2001

The failure of Daudi cells to express the cellular prion protein is caused by a lack of glycosyl-phosphatidylinositol anchor formation.

The cellular prion protein (PrPc) is a glycosyl-phosphatidylinositol (GPI)-linked cell surface protein, which is expressed at high density on nervous tissues and at lower levels on most other solid-organ tissues. It is also expressed on peripheral blood mononuclear cells (PBMC) of all lineages. In lymphocytes, its level of expression is dependent upon the state of cell activation, and polyclonal anti-PrP antisera partially block lectin-induced T-cell activation, suggesting a functional role of the protein in this process. Using the monoclonal antibody (mAb) 3F4 we examined PrPc surface immunoreactivity on leukaemic cell lines of T- and B-cell origin, and unexpectedly observed a complete lack of PrPc cell-surface expression in Daudi cells, while all other cell lines displayed discernible reactivity. We demonstrated the intracellular presence of PrP-specific mRNA and PrP protein. The lack of surface PrPc is unrelated to the well-known defect of beta2-microglobulin (beta2m) expression in Daudi cells as other beta2m-deficient cells, such as the melanoma cell line F0-1 and spleen cells from beta2m gene-deleted mice, were not deficient in cell-surface PrPc. Daudi cells failed to bind antibodies directed against all GPI-linked cell surface proteins. In somatic hybridization experiments using murine spleen cells as partners, we observed de novo expression of human PrPc, CD55 and CD59, thus demonstrating in Daudi cells the availability of these gene products for GPI linkage and cell-surface expression.

Antibodies, Monoclonal↗

PubMed1996

Soluble tumor necrosis factor receptor inhibits interleukin 12 production by stimulated human adult microglial cells in vitro.

IL-12 is a cytokine detected in active lesions in multiple sclerosis (MS) and promotes the acquisition of a Th1 cytokine profile by CD4+ T cells. Autoreactive T cells recovered from the central nervous system of animals with experimental autoimmune encephalomyelitis (EAE), a disease model for MS, display this phenotype. We demonstrate that human central nervous system-derived microglia, but not astroglia, can produce IL-12 in vitro. Under basal culture conditions, human adult microglia do not express detectable levels of IL-12, although these cells show some degree of activation as assessed by expression of the immunoregulatory surface molecules HLA-DR and B7 as well as low levels of TNF-alpha mRNA. Following activation with LPS, IL-12 p40 mRNA and p70 protein can be readily detected. IL-12 production is preceded by TNF-alpha production and is inhibited by recombinant soluble human TNF receptor (II)-IgG1 fusion protein (shu-TNF-R). These data indicate regulation of IL-12 by an autocrine-dependent feedback loop, providing an additional mechanism whereby shu-TNF-R, now used in clinical trials in MS, may be exerting its effect.

Adult↗

PubMed1996

Emerging problems in prion disease.

The authors comment on the report by Drs. Chris MacKnight and Kenneth Rockwood (see pages 529 to 536 of this issue) on the implications for Canadian physicians of human prion diseases. They argue that there is reason for concern about the possible crossover of bovine spongiform encephalopathy to humans in the form of a variant of Creutzfeldt-Jakob disease (CJD) recently identified in the United Kingdom. A second emerging issue is the potential for the causative agent of CJD to be transmitted through donated blood and tissue. Although the epidemiologic evidence suggests that this risk is remote, current national and international initiatives to increase surveillance for new cases of CJD are timely.

Animals↗

PubMed1996

Transient immunosuppression by FK506 permits a sustained high-level dystrophin expression after adenovirus-mediated dystrophin minigene transfer to skeletal muscles of adult dystrophic (mdx) mice.

Adenovirus (AV)-mediated gene transfer into skeletal muscles of adult immune-competent animals has been limited by the fact that a cell-mediated immune attack of the host against transduced muscle fibers prevented efficient long-term transgene expression. More recently, various immunomodulating strategies have been shown to improve the longevity of transgene expression after AV-mediated gene transfer. In this study we treated adult dystrophic (mdx) mice with daily subcutaneous injections of the immunosuppressive drug FK506 (tacrolimus) over 5, 10, 30 and 60 days after AV-mediated dystrophin gene transfer and compared the transduction level with saline-injected mdx controls. We show that daily FK506 treatment after AV-mediated dystrophin gene transfer into adult mdx muscle results in the maintenance of the initial transgene expression for at least 2 months, even when FK506 treatment was discontinued after 1 month. This is in keeping with the marked reduction of inflammatory infiltrates and the reduced activation level (inducible nitric oxide synthase) of macrophages in adenoviral recombinant (AVR)-injected muscles of FK506-treated animals. Moreover, we find that FK506 efficiently suppresses the humoral immune response against both the vector proteins and the transgene protein product (dystrophin). Furthermore, we demonstrate that continuous FK506 treatment over 30 days significantly improves the efficiency of gene transfer when the same vector is readministered to an animal which had been transduced 20 days earlier. In conclusion, the data suggest that sensitization by the initial antigenic load of the AVR application plays a pivotal role in triggering the humoral and cellular immune response of the host, which can be significantly counteracted by relatively short-term immunosuppressive treatment. These findings have important implications for the design of future human trials for gene replacement therapy in Duchenne muscular dystrophy.

Adenoviridae↗

PubMed1994

Selective enrichment of Th1 CD45RBlow CD4+ T cells in autoimmune infiltrates in experimental allergic encephalomyelitis.

The cytokine effector status of CD4+ T cells from lymph nodes (LN) and the central nervous system (CNS) of SJL/J mice immunized with autoantigen in adjuvant for the induction of experimental allergic encephalomyelitis (EAE) was compared. CD4+ T cells were FACS sorted based on the levels of expression of the activation marker CD45RB. Low levels of expression of this surface marker are induced by antigen recognition and are associated with 'effector' T cell function. Reverse transcriptase polymerase chain reaction (PCR) was used to analyze the expression of different T cell cytokine genes in the sorted populations. CD45RBlow cells constituted a minority of CD4+ cells in the LN and expressed elevated levels of IL-2, IFN-gamma, and IL-4 mRNA, whereas the CD45RBlow CD4+ population did not express detectable message for these cytokines under linear PCR conditions. By contrast to the LN, CD4+ cells from the CNS were predominantly CD45RBlow and expressed readily detectable levels of IL-2 and IFN-gamma mRNA, but almost no IL-4 transcription could be detected. IL-4 mRNA levels in CNS were 100- to 250-fold lower than in LN. Also, IL-4 message could not be detected in the CNS 1 week after remission. A cytokine-specific immunocytochemical single cell staining technique was used to enumerate cytokine-producing cells in LN cell populations and in CNS infiltrates. Between 1 and 5% cells in isolated LN cells produced detectable IL-2 and IFN-gamma. By contrast, the frequency of cytokine-producing cells stained in perivascular infiltrates in frozen sections from the brains of animals with active EAE was 10-fold higher.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗