参考文献

Current evidence supports a model in which the low-affinity state of the platelet integrin alphaIIbbeta3 results from alphaIIbbeta3 adopting a bent conformation. To assess alphaIIbbeta3 biogenesis and how alphaIIbbeta3 initially adopts the bent conformation,we mapped the conformational states occupied by alphaIIb and beta3 during biogenesis using conformation-specific monoclonal antibodies (mAbs). We found that alphaIIbbeta3 complex formation was not limited by the availability of either free pro-alphaIIb or free beta3,suggesting that other molecules,perhaps chaperones,control complex formation. Five beta3-specific,ligand-induced binding site (LIBS) mAbs reacted with much or all free beta3 but not with beta3 when in complex with mature alphaIIb,suggesting that beta3 adopts its mature conformation only after complex formation. Conversely,2 alphaIIb-specific LIBS mAbs directed against the alphaIIb Calf-2 region adjacent to the membrane reacted with only minor fractions of free pro-alphaIIb,raising the possibility that pro-alphaIIb adopts a bent conformation early in biogenesis. Our data suggest a working model in which pro-alphaIIb adopts a bent conformation soon after synthesis,and then beta3 assumes its bent conformation by virtue of its interaction with the bent pro-alphaIIb. View Publication

An urgent need exists to devise strategies to augment antiviral immune responses in patients with HIV who are virologically well controlled and immunologically stable on highly active antiretroviral therapy (HAART). The objective of this study was to compare the immunomodulatory effects of the cytokines interleukin (IL)-21 with IL-15 on CD8 T cells in patients with HIV RNA of less than 50 copies/mL and CD4 counts greater than 200 cells/mm.(3) Patient CD8 T cells displayed skewed maturation and decreased perforin expression compared with healthy controls. Culture of freshly isolated patient peripheral-blood mononuclear cells (PBMCs) for 5 hours to 5 days with IL-21 resulted in up-regulation of perforin in CD8 T cells,including memory and effector subsets and virus-specific T cells. IL-21 did not induce T-cell activation or proliferation,nor did it augment T-cell receptor (TCR)-induced degranulation. Treatment of patient PBMCs with IL-15 resulted in induction of perforin in association with lymphocyte proliferation and augmentation of TCR-induced degranulation. Patient CD8 T cells were more responsive to cytokine effects than the cells of healthy volunteers. We conclude that CD8 T cells of patients with HIV can be modulated by IL-21 to increase perforin expression without undergoing overt cellular activation. IL-21 could potentially be useful for its perforin-enhancing properties in anti-HIV immunotherapy. View Publication

Macroautophagy (hereafter referred to as autophagy) is a well-conserved intracellular degradation process. Recent studies examining cells lacking the autophagy genes Atg5 and Atg7 have demonstrated that autophagy plays essential roles in cell survival during starvation,in innate cell clearance of microbial pathogens,and in neural cell maintenance. However,the role of autophagy in T lymphocyte development and survival is not known. Here,we demonstrate that autophagosomes form in primary mouse T lymphocytes. By generating Atg5-/- chimeric mice,we found that Atg5-deficient T lymphocytes underwent full maturation. However,the numbers of total thymocytes and peripheral T and B lymphocytes were reduced in Atg5 chimeras. In the periphery,Atg5-/- CD8+ T lymphocytes displayed dramatically increased cell death. Furthermore,Atg5-/- CD4+ and CD8+ T cells failed to undergo efficient proliferation after TCR stimulation. These results demonstrate a critical role for Atg5 in multiple aspects of lymphocyte development and function and suggest that autophagy may be essential for both T lymphocyte survival and proliferation. View Publication

Interferon regulatory factor-1 (IRF-1) is an important transcription factor that mediates interferon-gamma (IFN-gamma)-induced cell-signaling events. In this study,we examined whether 17beta-estradiol alters IRF-1 in splenic lymphocytes,in view of the immunomodulatory effects of this natural female sex hormone including its ability to alter IFN-gamma levels. We find that IRF-1 expression is markedly downregulated in splenocytes or purified T-cells from estrogen-treated mice at all time points studied when compared with their placebo counterparts. This decrease in IRF-1 in splenocytes from estrogen-treated mice is neither due to upregulation of IRF-1-interfering proteins (nucleophosmin or signal transducer and activator of transcription (STAT)-5) nor due to alternatively spliced IRF-1 mRNA. Given that IFN-gamma is a potent inducer of IRF-1,direct addition of recombinant IFN-gamma to splenocytes from either wild-type or IFN-gamma-knockout mice,or the addition of recombinant IFN-gamma to purified T-cells,was expected to stimulate IRF-1 expression. However,robust expression of IRF-1 in cells from estrogen-treated mice was not seen,unlike what was observed in cells from placebo-treated mice. Diminished IFN-gamma induction of IRF-1 in cells from estrogen-treated mice was noticed despite comparable phosphorylated STAT-1 activation. These studies are the first to show that estrogen regulates IFN-gamma-inducible IRF-1 in lymphoid cells,a finding that may have implications to IFN-gamma-regulated immune and vascular diseases. View Publication

Lymphocyte traffic is required to maintain homeostasis and perform appropriate immunological reactions. To migrate into inflamed tissues,lymphocytes must acquire spatial and functional asymmetries. Mitochondria are highly dynamic organelles that distribute in the cytoplasm to meet specific cellular needs,but whether this is essential to lymphocyte functions is unknown. We show that mitochondria specifically concentrate at the uropod during lymphocyte migration by a process involving rearrangements of their shape. Mitochondrial fission facilitates relocation of the organelles and promotes lymphocyte chemotaxis,whereas mitochondrial fusion inhibits both processes. Our data substantiate a new role for mitochondrial dynamics and suggest that mitochondria redistribution is required to regulate the motor of migrating cells. View Publication

We have established several HLA-A2.1-transgenic rabbit lines to provide a host to study CD8(+) T cell responses during virus infections. HLA-A2.1 protein expression was detected on cell surfaces within various organ tissues. Continuous cultured cells from these transgenic rabbits were capable of presenting both endogenous and exogenous HLA-A2.1-restricted epitopes to an HLA-A2.1-restricted epitope-specific CTL clone. A DNA vaccine containing an HLA-A2.1-restricted human papillomavirus type 16 E7 epitope (amino acid residues 82-90) stimulated epitope-specific CTLs in both PBLs and spleen cells of transgenic rabbits. In addition,vaccinated transgenic rabbits were protected against infection with a mutant cottontail rabbit papillomavirus DNA containing an embedded human papillomavirus type 16 E7/82-90 epitope. Complete protection was achieved using a multivalent epitope DNA vaccine based on epitope selection from cottontail rabbit papillomavirus E1 using MHC class I epitope prediction software. HLA-A2.1-transgenic rabbits will be an important preclinical animal model system to study virus-host interactions and to assess specific targets for immunotherapy. View Publication

Chaetocin,a thiodioxopiperazine natural product previously unreported to have anticancer effects,was found to have potent antimyeloma activity in IL-6-dependent and -independent myeloma cell lines in freshly collected sorted and unsorted patient CD138(+) myeloma cells and in vivo. Chaetocin largely spares matched normal CD138(-) patient bone marrow leukocytes,normal B cells,and neoplastic B-CLL (chronic lymphocytic leukemia) cells,indicating a high degree of selectivity even in closely lineage-related B cells. Furthermore,chaetocin displays superior ex vivo antimyeloma activity and selectivity than doxorubicin and dexamethasone,and dexamethasone- or doxorubicin-resistant myeloma cell lines are largely non-cross-resistant to chaetocin. Mechanistically,chaetocin is dramatically accumulated in cancer cells via a process inhibited by glutathione and requiring intact/unreduced disulfides for uptake. Once inside the cell,its anticancer activity appears mediated primarily through the imposition of oxidative stress and consequent apoptosis induction. Moreover,the selective antimyeloma effects of chaetocin appear not to reflect differential intracellular accumulation of chaetocin but,instead,heightened sensitivity of myeloma cells to the cytotoxic effects of imposed oxidative stress. Considered collectively,chaetocin appears to represent a promising agent for further study as a potential antimyeloma therapeutic. View Publication

Autoreactive memory T lymphocytes are implicated in the pathogenesis of autoimmune diseases. Here we demonstrate that disease-associated autoreactive T cells from patients with type-1 diabetes mellitus or rheumatoid arthritis (RA) are mainly CD4+ CCR7- CD45RA- effector memory T cells (T(EM) cells) with elevated Kv1.3 potassium channel expression. In contrast,T cells with other antigen specificities from these patients,or autoreactive T cells from healthy individuals and disease controls,express low levels of Kv1.3 and are predominantly naïve or central-memory (T(CM)) cells. In T(EM) cells,Kv1.3 traffics to the immunological synapse during antigen presentation where it colocalizes with Kvbeta2,SAP97,ZIP,p56(lck),and CD4. Although Kv1.3 inhibitors [ShK(L5)-amide (SL5) and PAP1] do not prevent immunological synapse formation,they suppress Ca2+-signaling,cytokine production,and proliferation of autoantigen-specific T(EM) cells at pharmacologically relevant concentrations while sparing other classes of T cells. Kv1.3 inhibitors ameliorate pristane-induced arthritis in rats and reduce the incidence of experimental autoimmune diabetes in diabetes-prone (DP-BB/W) rats. Repeated dosing with Kv1.3 inhibitors in rats has not revealed systemic toxicity. Further development of Kv1.3 blockers for autoimmune disease therapy is warranted. View Publication

The chemokine RANTES (regulated upon activation normal T cell expressed and secreted) is expressed late" (3 to 5 days) after activation in T lymphocytes. In order to understand the molecular events that accompany changes in gene expression� View Publication

Despite considerable success in treating newly diagnosed childhood acute lymphoblastic leukemia (ALL),relapsed disease remains a significant clinical challenge. Using a NOD/SCID mouse xenograft model,we report that immunostimulatory DNA oligonucleotides containing CpG motifs (CpG ODNs) stimulate significant immune activity against primary human ALL cells in vivo. The administration of CpG ODNs induced a significant reduction in systemic leukemia burden,mediated continued disease control,and significantly improved survival of mice with established human ALL. The death of leukemia cells in vivo was independent of the ability of ALL cells to respond directly to CpG ODNs and correlated with the production of IL-12p70,IFN-alpha,and IFN-gamma by the host. In addition,depletion of natural killer cells by anti-asialo-GM1 treatment significantly reduced the in vivo antileukemic activity of CpG ODN. This antileukemia effect was not limited to the xenograft model because natural killer cell-dependent killing of ALL by human peripheral blood mononuclear cells (PBMCs) was also increased by CpG ODN stimulation. These results suggest that CpG ODNs have potential as therapeutic agents for the treatment of ALL. View Publication