技术资料

HIV-1 infection is associated with increased risk for B-cell lymphomas. How HIV infection promotes the development of lymphoma is unclear,but it may involve chronic B-cell activation,inflammation,and/or impaired immunity,possibly leading to a loss of control of oncogenic viruses and reduced tumor immunosurveillance. We hypothesized that HIV structural proteins may contribute to lymphomagenesis directly,because they can persist long term in lymph nodes in the absence of viral replication. The HIV-1 transgenic mouse Tg26 carries a noninfectious HIV-1 provirus lacking part of the gag-pol region,thus constituting a model for studying the effects of viral products in pathogenesis. Approximately 15% of Tg26 mice spontaneously develop leukemia/lymphoma. We investigated which viral proteins are associated with the development of leukemia/lymphoma in the Tg26 mouse model,and performed microarray analysis on RNA from spleen and lymph nodes to identify potential mechanisms of lymphomagenesis. Of the viral proteins examined,only expression of HIV-1 matrix protein p17 was associated with leukemia/lymphoma development and was highly expressed in bone marrow before disease. The tumor cells resembled pro-B cells,and were CD19(+)IgM(-)IgD(-)CD93(+)CD43(+)CD21(-)CD23(-)VpreB(+)CXCR4(+) Consistent with the pro-B-cell stage of B-cell development,microarray analysis revealed enrichment of transcripts,including Rag1,Rag2,CD93,Vpreb1,Vpreb3,and Igll1 We confirmed RAG1 expression in Tg26 tumors,and hypothesized that HIV-1 matrix protein p17 may directly induce RAG1 in B cells. Stimulation of human activated B cells with p17 enhanced RAG1 expression in three of seven donors,suggesting that intracellular signaling by p17 may lead to genomic instability and transformation. View Publication

During an immune response,activated antigen (Ag)-specific T cells condition dendritic cells (DCs) to enhance DC function and survival within the inflamed draining lymph node (LN). It has been difficult to ascertain the role of the tumor necrosis factor (TNF) superfamily member lymphotoxin-alphabeta (LTalphabeta) in this process because signaling through the LTbeta-receptor (LTbetaR) controls multiple aspects of lymphoid tissue organization. To resolve this,we have used an in vivo system where the expression of TNF family ligands is manipulated only on the Ag-specific T cells that interact with and condition Ag-bearing DCs. We report that LTalphabeta is a critical participant required for optimal DC function,independent of its described role in maintaining lymphoid tissue organization. In the absence of LTalphabeta or CD40L on Ag-specific T cells,DC dysfunction could be rescued in vivo via CD40 or LTbetaR stimulation,respectively,suggesting that these two pathways cooperate for optimal DC conditioning. View Publication

Natural killer (NK) cells are thought to develop from common lymphoid progenitors in the bone marrow. However,immature thymocytes also retain NK potential. Currently,the contribution of the thymus-dependent pathway in normal steady-state NK-cell development is unknown. Here,we show that TCRgamma genes are rearranged in approximately 5% of neonatal and 1% of adult mouse splenic NK cells,and similar levels are detected in NK cells from TCRbeta,delta double-knockout mice,excluding the possibility of T-cell contamination. NK-cell TCRgamma gene rearrangement is thymus dependent because this rearrangement is undetectable in nude mouse NK cells. These results change the current view of NK-cell development and show that a subset of NK cells develops from immature thymocytes that have rearranged TCRgamma genes. View Publication

Granulocyte colony-stimulating factor (G-CSF),the prototypical mobilizing cytokine,induces hematopoietic stem and progenitor cell (HSPC) mobilization from the bone marrow in a cell-nonautonomous fashion. This process is mediated,in part,through suppression of osteoblasts and disruption of CXCR4/CXCL12 signaling. The cellular targets of G-CSF that initiate the mobilization cascade have not been identified. We use mixed G-CSF receptor (G-CSFR)-deficient bone marrow chimeras to show that G-CSF-induced mobilization of HSPCs correlates poorly with the number of wild-type neutrophils. We generated transgenic mice in which expression of the G-CSFR is restricted to cells of the monocytic lineage. G-CSF-induced HSPC mobilization,osteoblast suppression,and inhibition of CXCL12 expression in the bone marrow of these transgenic mice are intact,demonstrating that G-CSFR signals in monocytic cells are sufficient to induce HSPC mobilization. Moreover,G-CSF treatment of wild-type mice is associated with marked loss of monocytic cells in the bone marrow. Finally,we show that bone marrow macrophages produce factors that support the growth and/or survival of osteoblasts in vitro. Together,these data suggest a model in which G-CSFR signals in bone marrow monocytic cells inhibit the production of trophic factors required for osteoblast lineage cell maintenance,ultimately leading to HSPC mobilization. View Publication

A new entity of acute leukemia coexpressing CD4(+)CD56(+) markers without any other lineage-specific markers has been identified recently as arising from lymphoid-related plasmacytoid dendritic cells (pDCs). In our laboratory,cells from a patient with such CD4(+)CD56(+) lineage-negative leukemia were unexpectedly found to also express the myeloid marker CD33. To confirm the diagnosis of pDC leukemia despite the CD33 expression,we demonstrated that the leukemic cells indeed exhibited pDC phenotypic and functional properties. In 7 of 8 other patients with CD4(+)CD56(+) pDC malignancies,we were able to confirm that the tumor cells expressed CD33 although with variable expression levels. CD33 expression was shown by flow cytometry,reverse transcriptase-polymerase chain reaction,and immunoblot analysis. Furthermore,CD33 monoclonal antibody stimulation of purified CD4(+)CD56(+) leukemic cells led to cytokine secretion,thus confirming the presence of a functional CD33 on these leukemic cells. Moreover,we found that circulating pDCs in healthy individuals also weakly express CD33. Overall,our results demonstrate that the expression of CD33 on CD4(+)CD56(+) lineage-negative cells should not exclude the diagnosis of pDC leukemia and underline that pDC-specific markers should be used at diagnosis for CD4(+)CD56(+) malignancies. View Publication