Prolonged Activation of Virus-Specific CD8(+)T Cells after Acute B19 Infection

BACKGROUND: Human parvovirus B19 (B19) is a ubiquitous and clinically significant pathogen, causing erythema infectiosum, arthropathy, transient aplastic crisis, and intrauterine fetal death. The phenotype of CD8(+) T cells in acute B19 infection has not been studied previously. METHODS AND FINDINGS: The number and phenotype of B19-specific CD8(+) T cell responses during and after acute adult infection was studied using HLA–peptide multimeric complexes. Surprisingly, these responses increased in magnitude over the first year post-infection despite resolution of clinical symptoms and control of viraemia, with T cell populations specific for individual epitopes comprising up to 4% of CD8(+) T cells. B19-specific T cells developed and maintained an activated CD38(+) phenotype, with strong expression of perforin and CD57 and downregulation of CD28 and CD27. These cells possessed strong effector function and intact proliferative capacity. Individuals tested many years after infection exhibited lower frequencies of B19-specific cytotoxic T lymphocytes, typically 0.05%–0.5% of CD8(+) T cells, which were perforin, CD38, and CCR7 low. CONCLUSION: This is the first example to our knowledge of an “acute” human viral infection inducing a persistent activated CD8(+) T cell response. The likely explanation—analogous to that for cytomegalovirus infection—is that this persistent response is due to low-level antigen exposure. CD8(+) T cells may contribute to the long-term control of this significant pathogen and should be considered during vaccine development

Impaired Cell Surface Expression of HLA-B Antigens on Mesenchymal Stem Cells and Muscle Cell Progenitors

HLA class-I expression is weak in embryonic stem cells but increases rapidly during lineage progression. It is unknown whether all three classical HLA class-I antigens follow the same developmental program. In the present study, we investigated allele-specific expression of HLA-A, -B, and -C at the mRNA and protein levels on human mesenchymal stem cells from bone marrow and adipose tissue as well as striated muscle satellite cells and lymphocytes. Using multicolour flow cytometry, we found high cell surface expression of HLA-A on all stem cells and PBMC examined. Surprisingly, HLA-B was either undetectable or very weakly expressed on all stem cells protecting them from complement-dependent cytotoxicity (CDC) using relevant human anti-B and anti-Cw sera. IFNγ stimulation for 48–72 h was required to induce full HLA–B protein expression. Quantitative real-time RT-PCR showed that IFNγ induced a 9–42 fold increase of all six HLA-A,-B,-C gene transcripts. Interestingly, prior to stimulation, gene transcripts for all but two alleles were present in similar amounts suggesting that post-transcriptional mechanisms regulate the constitutive expression of HLA-A,-B, and -C. Locus-restricted expression of HLA-A, -B and -C challenges our current understanding of the function of these molecules as regulators of CD8+ T-cell and NK-cell function and should lead to further inquiries into their expression on other cell types

Contribution of flowering synchrony to species richness in dry meadow

Background: Identification of surface markers for prospective isolation of functionally homogenous populations of human skeletal (stromal, mesenchymal) stem cells (hMSCs) is highly relevant for cell therapy protocols. Thus, we examined the possible use of CD146 to subtype a heterogeneous hMSC population. Methods: Using flow cytometry and cell sorting, we isolated two distinct hMSC-CD146 and hMSC-CD146 cell populations from the telomerized human bone marrow-derived stromal cell line (hMSC-TERT). Cells were examined for differences in their size, shape and texture by using high-content analysis and additionally for their ability to differentiate toward osteogenesis in vitro and form bone in vivo, and their migrational ability in vivo and in vitro was investigated. Results: In vitro, the two cell populations exhibited similar growth rate and differentiation capacity to osteoblasts and adipocytes on the basis of gene expression and protein production of lineage-specific markers. In vivo, hMSC-CD146 and hMSC-CD146 cells formed bone and bone marrow organ when implanted subcutaneously in immune-deficient mice. Bone was enriched in hMSC-CD146 cells (12.6 % versus 8.1 %) and bone marrow elements enriched in implants containing hMSC-CD146 cells (0.5 % versus 0.05 %). hMSC-CD146 cells exhibited greater chemotactic attraction in a transwell migration assay and, when injected intravenously into immune-deficient mice following closed femoral fracture, exhibited wider tissue distribution and significantly increased migration ability as demonstrated by bioluminescence imaging. Conclusion: Our studies demonstrate that CD146 defines a subpopulation of hMSCs capable of bone formation and in vivo trans-endothelial migration and thus represents a population of hMSCs suitable for use in clinical protocols of bone tissue regeneration

A Study of Metal Additive Manufacturing: DMLS Design for Optimizing Automobile Components

abstract: Automobiles can advance greatly with the introduction of metal additive manufactured components. Additive tooling is slowly becoming additive manufacturing and someday the technology will be advanced enough that high volume can be supported. This research was conducted in order to show the advantages metal additive manufacturing has in the automobile industry. One large advantage to metal additive manufacturing is mass reduction. Components can be designed for production with different geometries than other manufacturing methods. The change in geometry can significantly reduce the product volume and therefore mass. Overall, mass reduction in the automotive industry is beneficial. Mass reduction can increase performance and fuel economy of the car. Once metal additive manufacturing becomes capable of higher production, metal additive manufacturing will play a major role in automobile manufacturing. Research was conducted to design and produce an optimized AC compressor bracket. The bracket was designed to the specifications of the OEM component, and the mass was reduced by more than half

Sustained CD8(+) T-Cell Responses Induced after Acute Parvovirus B19 Infection in Humans

Murine models have suggested that CD8(+) T-cell responses peak early in acute viral infections and are not sustained, but no evidence for humans has been available. To address this, we longitudinally analyzed the CD8(+) T-cell response to human parvovirus B19 in acutely infected individuals. We observed striking CD8(+) T-cell responses, which were sustained or even increased over many months after the resolution of acute disease, indicating that CD8(+) T cells may play a prominent role in the control of parvovirus B19 and other acute viral infections of humans, including potentially those generated by live vaccines