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Alcohol abuse predisposes the host to bacterial infections. In response to bacterial infection,the bone marrow hematopoietic activity shifts toward granulocyte production,which is critical for enhancing host defense. This study investigated the hematopoietic precursor cell response to bacteremia and how alcohol affects this response. Acute alcohol intoxication was induced in BALB/c mice 30 min before initiation of Escherichia coli bacteremia. Bacteremia caused a significant increase in the number of bone marrow lineage (lin(-))-c-kit(+)Sca-1(+) cells. Marrow lin(-)c-kit(+)Sca-1(+) cells isolated from bacteremic mice showed an increase in CFU-granulocyte/macrophage activity compared with controls. In addition to enhanced proliferation of lin(-)c-kit(+)Sca-1(+) cells as reflected by BrdU incorporation,phenotypic inversion of lin(-)c-kit(+)Sca-1(+)Sca-1(-) cells primarily accounted for the rapid increase in marrow lin(-)c-kit(+)Sca-1(+) cells following bacteremia. Bacteremia increased plasma concentration of TNF-alpha. Culture of marrow lin(-)c-kit(+)Sca-1(+)Sca-1(-) cells with murine rTNF-alpha for 24 h caused a dose-dependent increase in conversion of these cells to lin(-)c-kit(+)Sca-1(+) cells. Sca-1 mRNA expression by the cultured cells was also up-regulated following TNF-alpha stimulation. Acute alcohol intoxication inhibited the increase in the number of lin(-)c-kit(+)Sca-1(+) cells in the bone marrow after E. coli infection. Alcohol impeded the increase in BrdU incorporation into marrow lin(-)c-kit(+)Sca-1(+) cells in response to bacteremia. Alcohol also suppressed the plasma TNF-alpha response to bacteremia and inhibited TNF-alpha-induced phenotypic inversion of lin(-)c-kit(+)Sca-1(+)Sca-1(-) cells in vitro. These data show that alcohol inhibits the hematopoietic precursor cell response to bacteremia,which may serve as one mechanism underlying the impaired host defense in alcohol abusers with severe bacterial infections. View Publication

Increased proportions of CD8 T lymphocytes lacking expression of the CD28 costimulatory receptor have been documented during both aging and chronic infection with HIV-1,and their abundance correlates with numerous deleterious clinical outcomes. CD28-negative cells also arise in cell cultures of CD8(+)CD28(+) following multiple rounds of Ag-driven proliferation,reaching the end stage of replicative senescence. The present study investigates the role of a second T cell costimulatory receptor component,adenosine deaminase (ADA),on the process of replicative senescence. We had previously reported that CD28 signaling is required for optimal telomerase upregulation. In this study,we show that the CD8(+)CD28(+) T lymphocytes that are ADA(+) have significantly greater telomerase activity than those that do not express ADA and that ADA is progressively lost as cultures progress to senescence. Because ADA converts adenosine to inosine,cells lacking this enzyme might be subject to prolonged exposure to adenosine,which has immunosuppressive effects. Indeed,we show that chronic exposure of CD8 T lymphocytes to exogenous adenosine accelerates the process of replicative senescence,causing a reduction in overall proliferative potential,reduced telomerase activity,and blunted IL-2 gene transcription. The loss of CD28 expression was accelerated,in part due to adenosine-induced increases in constitutive caspase-3,known to act on the CD28 promoter. These findings provide the first evidence for a role of ADA in modulating the process of replicative senescence and suggest that strategies to enhance this enzyme may lead to novel therapeutic approaches for pathologies associated with increases in senescent CD8 T lymphocytes. View Publication

Effector cells derived from central memory CD8(+) T cells were reported to engraft and survive better than those derived from effector memory populations,suggesting that they are superior for use in adoptive immunotherapy studies. However,previous studies did not evaluate the relative efficacy of effector cells derived from naïve T cells. We sought to investigate the efficacy of tumor-specific effector cells derived from naïve or central memory T-cell subsets using transgenic or retrovirally transduced T cells engineered to express a tumor-specific T-cell receptor. We found that naïve,rather than central memory T cells,gave rise to an effector population that mediated superior antitumor immunity upon adoptive transfer. Effector cells developed from naïve T cells lost the expression of CD62L more rapidly than those derived from central memory T cells,but did not acquire the expression of KLRG-1,a marker for terminal differentiation and replicative senescence. Consistent with this KLRG-1(-) phenotype,naïve-derived cells were capable of a greater proliferative burst and had enhanced cytokine production after adoptive transfer. These results indicate that insertion of genes that confer antitumor specificity into naïve rather than central memory CD8(+) T cells may allow superior efficacy upon adoptive transfer. View Publication

Bone marrow mesenchymal stem cells (MSC) have potent immunosuppressive properties and have been advocated for therapeutic use in humans. The nature of their suppressive capacity is poorly understood but is said to be a primitive stem cell function. Demonstration that adult stromal cells such as fibroblasts (Fb) can modulate T cells would have important implications for immunoregulation and cellular therapy. In this report,we show that dermal Fb inhibit allogeneic T cell activation by autologously derived cutaneous APCs and other stimulators. Fb mediate suppression through soluble factors,but this is critically dependent on IFN-gamma from activated T cells. IFN-gamma induces IDO in Fb,and accelerated tryptophan metabolism is at least partly responsible for suppression of T cell proliferation. T cell suppression is reversible,and transient exposure to Fb during activation reprograms T cells,increasing IL-4 and IL-10 secretion upon restimulation. Increased Th2 polarization by stromal cells is associated with amelioration of pathological changes in a human model of graft-vs-host disease. Dermal Fb are highly clonogenic in vitro,suggesting that Fb-mediated immunosuppression is not due to outgrowth of rare MSC,although dermal Fb remain difficult to distinguish from MSC by phenotype or transdifferentiation capacity. These results suggest that immunosuppression is a general property of stromal cells and that dermal Fb may provide an alternative and accessible source of cellular therapy. View Publication

B cell dysregulation in aging is thought to mostly occur in conventional B2 cells without affecting innate B1 cells. Elderly humans and mice also accumulate 4-1BBL(+)MHC class-I(Hi)CD86(Hi)B cells of unknown origin. In this article,we report that these cells,termed 4BL cells,are activated murine and possibly human B1a cells. The activation is mediated by aging human monocytes and murine peritoneal macrophages. They induce expression and activation of 4-1BBL and IFN-γR1 on B1a cells to subsequently upregulate membrane TNF-α and CD86. As a result,activated B1a/4BL cells induce expression of granzyme B in CD8(+)T cells by targeting TNFR2 via membrane TNF-α and providing costimulation with CD86. Thus,for the first time,to our knowledge,these results indicate that aging affects the function of B1a cells. Upon aging,these cells lose their tumor-supporting activity and become inducers of potentially antitumor and autoimmune CD8(+)T cells. View Publication

Group 2 innate lymphoid cells (ILC2s) in the lung are stimulated by inhaled allergens. ILC2s do not directly recognize allergens but they are stimulated by cytokines including interleukin (IL)-33 released by damaged epithelium. In response to allergens,lung ILC2s produce T helper 2 cell type cytokines inducing T cell-independent allergic lung inflammation. Here we examined the fate of lung ILC2s upon allergen challenges. ILC2s proliferated and secreted cytokines upon initial stimulation with allergen or IL-33,and this phase was followed by a contraction phase as cytokine production ceased. Some ILC2s persisted long after the resolution of the inflammation as allergen-experienced ILC2s and responded to unrelated allergens more potently than naive ILC2s,mediating severe allergic inflammation. The allergen-experienced ILC2s exhibited a gene expression profile similar to that of memory T cells. The memory-like properties of allergen-experienced ILC2s may explain why asthma patients are often sensitized to multiple allergens. View Publication

PURPOSE: Allogeneic T lymphocytes can induce regression of metastatic breast cancer through an immune-mediated graft-versus-tumor (GVT) effect in murine models. To determine if a clinical GVT effect exists against metastatic breast cancer,allogeneic lymphocytes were used as adoptive cellular therapy after a reduced-intensity chemotherapy conditioning regimen and allogeneic hematopoietic stem-cell transplantation (HSCT) from human leukocyte antigen-matched siblings. PATIENTS AND METHODS: Sixteen patients with metastatic breast cancer that had progressed after treatment with anthracyclines,taxanes,hormonal agents,and trastuzumab,received allogeneic HSCT. The reduced-intensity transplant conditioning regimen consisted of cyclophosphamide and fludarabine. To distinguish an immunological GVT effect from any antitumor effect of cytotoxic chemotherapy in the transplant-conditioning regimen,allogeneic T lymphocytes were removed from the stem-cell graft and were subsequently administered late postallogeneic HSCT. Allogeneic lymphocytes containing 1 x 10(6),5 x 10(6),and 10 x 10(6) CD3(+) cells/kg were infused on days +42,+70,and +98 post-allogeneic HSCT,respectively. RESULTS: Objective tumor regressions occurred after day +28 post-allogeneic HSCT in six patients and were attributed to allogeneic lymphocyte infusions. Two of these responding patients had disease progression post-allogeneic HSCT before subsequent tumor regression. Tumor regressions occurred concomitantly with the establishment of complete donor T-lymphoid engraftment,were associated with the development of graft-versus-host disease (GVHD),and were abrogated by subsequent systemic immunosuppression for GVHD. CONCLUSION: Allogeneic lymphocytes can induce regression of advanced metastatic breast cancer. These results indicate that an immunological GVT effect from allogeneic lymphocytes exists against metastatic breast cancer and provide rationale for further development of allogeneic cellular therapy for this largely incurable disease. View Publication

Autologous platelet rich plasma (PRP) is clinically used to induce repair of different tissues through the release of bioactive molecules. In some patients,the production of an efficient autologous PRP is unfeasible due to their compromised health. We developed an allogeneic PRP mismatched for AB0 and Rh antigens. To broadcast its clinical applications avoiding side effects the outcome of allogeneic PRP on immune response should be defined. Thus,we investigated whether PRP affected the differentiation of peripheral blood monocytes to dendritic cells upon stimulation with granulocyte monocyte colony stimulating factor and interleukin-4. Indeed,these cells are the main players of immune response and tissue repair. PRP inhibited the differentiation of monocytes to CD1a(+) dendritic cells and favored the expansion of phagocytic CD163(+) CD206(+) fibrocyte-like cells. These cells produced inteleukin-10 and prostaglandin-E2,but not interferon-γ,upon stimulation with lipopolysaccharides. Moreover,they promoted the expansion of regulatory CD4(+) CD25(+) FoxP3(+) T cells upon allostimulation or antigen specific priming. Finally,the conditioned medium harvested from monocytes differentiated with PRP triggered a strong chemotactic effect on mesenchymal cells in both scratch and transwell migration assays. These results strongly suggest that allogeneic PRP can foster the differentiation of monocytes to a regulatory anti-inflammatory population possibly favoring wound healing. View Publication

Aberrant T cell responses during T cell activation and immunological synapse (IS) formation have been described in systemic lupus erythematosus (SLE). Kv1.3 potassium channels are expressed in T cells where they compartmentalize at the IS and play a key role in T cell activation by modulating Ca(2+) influx. Although Kv1.3 channels have such an important role in T cell function,their potential involvement in the etiology and progression of SLE remains unknown. This study compares the K channel phenotype and the dynamics of Kv1.3 compartmentalization in the IS of normal and SLE human T cells. IS formation was induced by 1-30 min exposure to either anti-CD3/CD28 Ab-coated beads or EBV-infected B cells. We found that although the level of Kv1.3 channel expression and their activity in SLE T cells is similar to normal resting T cells,the kinetics of Kv1.3 compartmentalization in the IS are markedly different. In healthy resting T cells,Kv1.3 channels are progressively recruited and maintained in the IS for at least 30 min from synapse formation. In contrast,SLE,but not rheumatoid arthritis,T cells show faster kinetics with maximum Kv1.3 recruitment at 1 min and movement out of the IS by 15 min after activation. These kinetics resemble preactivated healthy T cells,but the K channel phenotype of SLE T cells is identical to resting T cells,where Kv1.3 constitutes the dominant K conductance. The defective temporal and spatial Kv1.3 distribution that we observed may contribute to the abnormal functions of SLE T cells. View Publication

CD4+CD25+ regulatory T cells play an important role in peripheral tolerance. Upon T cell receptor (TCR)-mediated activation,the cells fail to proliferate but are induced to have a suppressor function. The intracellular signaling events that lead to their responses have not been elucidated. In this study,we have examined the proximal TCR signaling events in freshly isolated human CD4+CD25+ regulatory T cells after TCR ligation. In contrast to CD4+CD25- T cells,TCR ligation of CD4+CD25+ regulatory T cells by anti-CD3 cross-linking resulted in a lower calcium influx and extracellular signal-regulated kinase 1/2 phosphorylation. Examination of the CD3zeta chain phosphorylation status indicated that CD4+CD25+ regulatory T cells have poor phosphorylation of the protein and consequently,reduced recruitment of zeta-associated protein-70 to the TCR immunoreceptor tyrosine motif. The adaptor protein,Src homology 2 domain-containing leukocyte phosphoprotein of 76 kDa,which relays signals to downstream signaling components,also showed reduced phosphorylation,which correlated with reduced VAV guanine nucleotide exchange factors association. Consistent with other findings,the defect is accompanied with impaired actin cap formation,implicating a failure of actin remodeling of the cells. Together,our results demonstrate that CD4+CD25+ regulatory T cells have altered TCR proximal signaling pathways,which could be critical for inducing the distinct behavior of these cells. View Publication

Type 2 innate lymphoid cells (ILC2) share cytokine and transcription factor expression with CD4+ Th2 cells,but functional diversity of the ILC2 lineage has yet to be fully explored. Here,we show induction of a molecularly distinct subset of activated lung ILC2,termed ILC210. These cells produce IL-10 and downregulate some pro-inflammatory genes. Signals that generate ILC210 are distinct from those that induce IL-13 production,and gene expression data indicate that an alternative activation pathway leads to the generation of ILC210. In vivo,IL-2 enhances ILC210 generation and is associated with decreased eosinophil recruitment to the lung. Unlike most activated ILC2,the ILC210 population contracts after cessation of stimulation in vivo,with maintenance of a subset that can be recalled by restimulation,analogous to T-cell effector cell and memory cell generation. These data demonstrate the generation of a previously unappreciated IL-10 producing ILC2 effector cell population. View Publication

The mutagenic enzyme activation-induced cytidine deaminase (AID) is required for immunoglobulin class switch recombination (CSR) and somatic hypermutation (SHM) in germinal center (GC) B cells. Deregulated expression of AID is associated with various B-cell malignancies and,currently,it remains unclear how AID activity is extinguished to avoid illegitimate mutations. AID has also been shown to be alternatively spliced in malignant B cells,and there is limited evidence that this also occurs in normal blood B cells. The functional significance of these splice variants remains unknown. Here we show that normal GC human B cells and blood memory B cells similarly express AID splice variants and show for the first time that AID splicing variants are singly expressed in individual normal B cells as well as malignant B cells from chronic lymphocytic leukemia patients. We further demonstrate that the alternative AID splice variants display different activities ranging from inactivation of CSR to inactivation or heightened SHM activity. Our data therefore suggest that CSR and SHM are differentially switched off by varying the expression of splicing products of AID at the individual cell level. Most importantly,our findings suggest a novel tumor suppression mechanism by which unnecessary AID mutagenic activities are promptly contained for GC B cells. View Publication