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Query: UMLS:C0432222 (SEM)
 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

During primary varicella-zoster virus (VZV) infection, it is presumed that virus is transmitted from mucosal sites to regional lymph nodes, where T cells become infected. The cell type responsible for VZV transport from the mucosa to the lymph nodes has not been defined. In this study, we assessed the susceptibility of human monocyte-derived dendritic cells to infection with VZV. Dendritic cells were inoculated with the VZV strain Schenke and assessed by flow cytometry for VZV and dendritic cell (CD1a) antigen expression. In five replicate experiments, 34.4% +/- 6.6% (mean +/- SEM) of CD1a(+) cells were also VZV antigen positive. Dendritic cells were also shown to be susceptible to VZV infection by the detection of immediate-early (IE62), early (ORF29), and late (gC) gene products in CD1a(+) dendritic cells. Infectious virus was recovered from infected dendritic cells, and cell-to-cell contact was required for transmission of virus to permissive fibroblasts. VZV-infected dendritic cells showed no significant decrease in cell viability or evidence of apoptosis and did not exhibit altered cell surface levels of major histocompatibility complex (MHC) class I, MHC class II, CD86, CD40, or CD1a. Significantly, when autologous T lymphocytes were incubated with VZV-infected dendritic cells, VZV antigens were readily detected in CD3(+) T lymphocytes and infectious virus was recovered from these cells. These data provide the first evidence that dendritic cells are permissive to VZV and that dendritic cell infection can lead to transmission of virus to T lymphocytes. These findings have implications for our understanding of how virus may be disseminated during primary VZV infection.
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PMID:Varicella-zoster virus infection of human dendritic cells and transmission to T cells: implications for virus dissemination in the host. 1139 Jun 20

Interactions between inducible co-stimulatory molecule (ICOS) and ICOS-ligand (ICOS-L) are crucial for T-cell co-stimulation, effector cell differentiation and memory CD8+ T-cell activation. Because in the muscle of patients with sporadic inclusion body myositis (sIBM) clonally expanded CD8+ T cells invade major histocompatibility complex (MHC) class I-expressing muscle fibres, we investigated ICOS.ICOS-L interactions and correlated their expression with perforin, a marker for cytotoxic effector function by autoinvasive CD8+ T cells. The mRNA from 20 muscle biopsies of sIBM, 20 non-inflammatory or dystrophic controls, two dermatomyositis (DM) and two polymyositis (PM) patients was reverse transcribed and reamplified by semi-quantitative and quantitative reverse transcription-polymerase chain reaction (RT-PCR), using primers for ICOS, ICOS-L and perforin. The glyceraldehyde 3-phosphate dehydrogenase (GAPDH)-normalized ratio of ICOS, ICOS-L and perforin expression was compared with the degree of endomysial inflammation. Protein expression of ICOS, ICOS-L and perforin was confirmed by immunohistochemistry. We demonstrate that ICOS-L mRNA was upregulated in sIBM (arbitrary units, median +/- SEM: 48.6 +/- 14.9) compared with controls (6.2 +/- 17.8, P < 0.05) and significantly correlated with the expression of ICOS (53.9 +/- 16.6 versus 6.7 +/- 8.9 in controls, P < 0.001). By triple labelling immunohistochemistry, the CD8+ T cells in sIBM and PM were found to invade ICOS-L- and MHC class I-co-expressing muscle fibres. Among the autoinvasive CD8+ T cells, however, only a subset of approximately 5-10% were ICOS positive, and thereby perceptive for ICOS.ICOS-L signalling at the immunological synapse. In contrast, in Duchenne muscular dystrophy and DM, although ICOS and ICOS-L mRNA expression was also increased, the majority of ICOS-L- and ICOS-positive cells were in the perimysial regions and connective tissue. The mRNA for perforin was increased in sIBM (28.1 +/- 8.7) compared with controls (4.3 +/- 11.2, P = 0.18), and significantly correlated with mRNA of ICOS, ICOS-L and the degree of endomysial inflammation as assessed in coded haematoxylin/eosin tissue sections. By triple immunohistochemical staining and cell counting, perforin granules were found in 71% of the autoinvasive CD8+ T cells that were also ICOS positive. Our data indicate that in sIBM there is upregulation of ICOS.ICOS-L co-stimulatory signalling in association with enhanced perforin expression by the autoinvasive CD8+ T cells. The findings support previous suggestions that in IBM, the muscle fibres have the capacity for antigen presentation, thereby activating a specific subset among the autoinvasive CD8+ T cells to exert a cytotoxic effect. The observations strengthen the immunopathogenesis of sIBM, and offer the basis for future therapeutic interventions targeting ICOS.ICOS-L co-stimulatory interactions.
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PMID:Upregulated inducible co-stimulator (ICOS) and ICOS-ligand in inclusion body myositis muscle: significance for CD8+ T cell cytotoxicity. 1504 91


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