Browsing by Author "Zhang, Li"

Now showing 1 - 4 of 4
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    Contact-dependent delivery of IL-2 by dendritic cells to CD4 T cells in the contraction phase promotes their long-term survival
    (2019-11-05) Tong, Dan; Zhang, Li; Ning, Fei; Xu, Ying; Hu, Xiaoyu; Shi, Yan
    Abstract Common γ chain cytokines are important for immune memory formation. Among them, the role of IL-2 remains to be fully explored. It has been suggested that this cytokine is critically needed in the late phase of primary CD4 T cell activation. Lack of IL-2 at this stage sets for a diminished recall response in subsequent challenges. However, as IL-2 peak production is over at this point, the source and the exact mechanism that promotes its production remain elusive. We report here that resting, previously antigen-stimulated CD4 T cells maintain a minimalist response to dendritic cells after their peak activation in vitro. This subtle activation event may be induced by DCs without overt presence of antigen and appears to be stronger if IL-2 comes from the same dendritic cells. This encounter reactivates a miniature IL-2 production and leads a gene expression profile change in these previously activated CD4 T cells. The CD4 T cells so experienced show enhanced reactivation intensity upon secondary challenges later on. Although mostly relying on in vitro evidence, our work may implicate a subtle programing for CD4 T cell survival after primary activation in vivo.
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    Direct economic burden of hepatitis B virus related diseases: evidence from Shandong, China
    (BioMed Central, 2013-01-31) Lu, Jingjing; Xu, Aiqiang; Wang, Jian; Zhang, Li; Song, Lizhi; Li, Renpeng; Zhang, Shunxiang; Zhuang, Guihua; Lu, Mingshan
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    The Pricing of Multiple Line P&C Insurance Based on the Full Information Underwriting Beta
    (HEC Montréal, 2009-10) Nielson, Norma; Zhang, Li
    This paper develops a financial model of insurance pricing that is able to price insurance by line in a multi-line property & casualty insurance company based on the Full Information Underwriting Beta Methodology. It extends the existing literature in insurance pricing in that the model is suitable for multi-line pricing and reflects the systematic risk of different business lines. Based on Canadian Property & Casualty insurance industry data, the primary empirical findings in this paper strongly reject the argument in prior studies that underwriting betas of distinct lines vary in proportion to the length of the period that the premium of the corresponding line can be kept for investment. The results also show that the expected underwriting profit margin of liability insurance is the lowest among three distinct business lines: auto insurance, property insurance, and liability insurance.