Autoantigen-specific regulatory T cells, a potential tool for immune-tolerance reconstitution in type-2 autoimmune hepatitis

Effector CD4 and CD8 T cell immune responses to cytochrome P450IID6 (CYP2D6), the autoantigen of autoimmune hepatitis type 2 (AIH-2), are permitted by a numerical and functional impairment of CD4(pos) CD25(high) regulatory T cells (T-regs). We aimed to investigate whether T-regs specific for CYP2D6 immunodominant regions and restricted by the appropriate human leukocyte antigen (HLA)-DR molecule can be generated in patients with AIH-2 and can control CD4 and CD8 T cell effectors targeting identical or overlapping CYP2D6 regions. CYP2D6-specific regulatory T cells (CYP2D6 T-regs) were obtained from peptide-pulsed monocyte-depleted peripheral blood mononuclear cells of 17 patients with AIH-2, who were positive for the predisposing HLA-DR7 and/or HLA-DR3 alleles. Their antigen specificity was assessed by cytofluorimetry using HLA class II tetramers and their cytokine profile by intracellular staining. T-reg ability to suppress was ascertained by measuring reduction of CD4(pos) CD25(neg) cell proliferation/effector cytokine secretion and of CD8 T cell cytotoxicity. The most efficient suppression of effector T cell proliferation, inflammatory cytokine release, and cytotoxicity was obtained by coculturing T-regs with CYP2D6-peptide-loaded semimature dendritic cells (smDCs), and smDC-CYP2D6 T-regs also expressed high levels of FOXP3 (forkhead box P3). Possession of the appropriate HLA-DR molecule and recognition of the CYP2D6 autoantigenic sequence were critical to the synergistic smDC-CYP2D6 T-reg immunoregulatory functions, and lack of either element led to poor control of responder cell proliferation and cytokine secretion. Moreover, interferon-γ neutralization significantly boosted the suppressive ability of CYP2D6 T-regs. CONCLUSION: T-regs generated under CYP2D6-specific conditions and cocultured with smDCs are highly effective at controlling autoreactive T cells, thus providing the basis for a powerful and tailored form of immunotherapy for AIH-2.     

Galectin-9 and T cell immunoglobulin mucin-3 pathway is a therapeutic target for type 1 diabetes

Galectin-9 (Gal-9), a ligand for T cell Ig mucin-3 (Tim-3), induces apoptosis in cluster of differentiation 4 (CD4)(+) Tim-3(+) T helper 1 (T(H)1) cells via the Gal-9-Tim-3 pathway and negatively regulates T(H)1 immunity. In turn, Gal-9 activates dendritic cells (DC) to produce TNF-α, which promotes the T(H)1 response. We investigated the efficacy of Gal-9 against T(H)1-mediated autoimmune diabetes in NOD mice and compared with anti-Tim-3 monoclonal antibody (RMT3-23), which inhibited the binding between Tim-3-Ig and Gal-9 in a solid-phase binding assay. mRNA expression of Gal-9 was prominently induced by the treatment of interferon-γ in MIN6 cells, and Gal-9 was also expressed in the pancreatic β-cells in NOD mice, suggesting Gal-9 may be released from pancreatic β-cells to terminate T(H)1-mediated inflammation. Long-term injection of Gal-9 exhibits preventive efficacy for development of diabetes in NOD mice, but RMT3-23 demonstrated further prominent therapeutic potential compared with Gal-9. Gal-9 induced apoptosis of CD4(+)Tim-3(+) T(H)1 cells at the concentration of 0.2 μM, whereas RMT3-23 failed to enhance the apoptosis of CD4(+)Tim-3(+) T(H)1 cells. In contrast, Gal-9 induced TNF-α production in cultured DC in a dose-dependent manner; however, RMT3-23 inhibited Gal-9-induced TNF-α production in a dose-dependent manner. Although Gal-9 exhibited certain therapeutic potential against autoimmune diabetes by enhancing apoptosis of CD4(+)Tim-3(+) T(H)1 cells, RMT3-23 exhibited prominent therapeutic efficacy by suppressing the TNF-α production and activation of DC. Taken together, the inhibition of the Gal-9-Tim-3 pathway on DC, upstream of T(H)1 response, may be a new target for the treatment of type 1 diabetes.     

Galectin-9 binding to Tim-3 renders activated human CD4+ T cells less susceptible to HIV-1 infection

Galectin-9 (Gal-9) is a tandem repeat-type member of the galectin family and is a ligand for T-cell immunoglobulin mucin domain 3 (Tim-3), a type-I glycoprotein that is persistently expressed on dysfunctional T cells during chronic infection. Studies in autoimmune diseases and chronic viral infections show that Tim-3 is a regulatory molecule that inhibits Th1 type immune responses. Here we show that soluble Gal-9 interacts with Tim-3 expressed on the surface of activated CD4(+) T cells and renders them less susceptible to HIV-1 infection and replication. The Gal-9/Tim-3 interaction on activated CD4(+) T cells, leads to down-regulation of HIV-1 coreceptors and up-regulation of the cyclin-dependent kinase inhibitor p21 (also known as cip-1 and waf-1). We suggest that higher expression of Tim-3 during chronic infection has evolved to limit persistent immune activation and associated tissue damage. These data demonstrate a novel mechanism for Gal-9/Tim-3 interactions to induce resistance of activated CD4(+) T cells to HIV-1 infection and suggest that Gal-9 may play a role in HIV-1 pathogenesis and could be used as a novel microbicide to prevent HIV-1 infection.     

Deficiency of forkhead box P3 and cytotoxic T-lymphocyte-associated antigen-4 gene expressions and impaired suppressor function of CD4+CD25+ T cells in patients with autoimmune hepatitis

Aim:  Recently, forkhead box P3 (Foxp3), cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4), glucocorticoid-induced tumor necrosis factor receptor family-related gene (GITR), and CD28 were identified as the key molecules that control the development and activation of CD4+CD25+ regulatory T cells (T-reg). We investigated the expression pattern of these molecules on T-reg, and investigated the ability of T-reg to produce cytokines in patients with autoimmune hepatitis (AIH).
Methods:  Fifteen patients with AIH and nine healthy patients were included. To determine the frequency of T-reg, a two-color flow cytometry analysis was performed. T-reg were isolated using immunomagnetic beads, and the mRNA levels of Foxp3 , CTLA-4, GITR , and CD28 were quantified by real-time polymerase chain reaction (PCR). The ability of T-reg to produce interferon-γ, interleukin (IL)-10, transforming growth factor-β, and tumor necrosis factor-α after stimulation by OKT3 was evaluated by measuring the levels of mRNA in T-reg by real-time PCR.
Results:  The frequency of T-reg was increased in AIH. The mRNA levels of Foxp3 and CTLA-4 were significantly lower in AIH. The ability of T-reg to produce IL-10 was impaired in AIH.
Conclusion:  We speculate that the inferiority of the Foxp3 and CTLA-4 gene expressions on T-reg results in the impaired suppressor function of T-reg, and eventually in the breakdown of self-tolerance.     

Deficiency of forkhead box P3 and cytotoxic T-lymphocyte-associated antigen-4 gene expressions and impaired suppressor function of CD4(+)CD25(+) T cells in patients with autoimmune hepatitis

Aim: Recently, forkhead box P3 (Foxp3), cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4), glucocorticoid-induced tumor necrosis factor receptor family-related gene (GITR), and CD28 were identified as the key molecules that control the development and activation of CD4+CD25+ regulatory T cells (T-reg). We investigated the expression pattern of these molecules on T-reg, and investigated the ability of T-reg to produce cytokines in patients with autoimmune hepatitis (AIH). Methods: Fifteen patients with AIH and nine healthy patients were included. To determine the frequency of T-reg, a two-color flow cytometry analysis was performed. T-reg were isolated using immunomagnetic beads, and the mRNA levels of Foxp3, CTLA-4, GITR, and CD28 were quantified by real-time polymerase chain reaction (PCR). The ability of T-reg to produce interferon-gamma, interleukin (IL)-10, transforming growth factor-beta, and tumor necrosis factor-alpha after stimulation by OKT3 was evaluated by measuring the levels of mRNA in T-reg by real-time PCR. Results: The frequency of T-reg was increased in AIH. The mRNA levels of Foxp3 and CTLA-4 were significantly lower in AIH. The ability of T-reg to produce IL-10 was impaired in AIH. Conclusion: We speculate that the inferiority of the Foxp3 and CTLA-4 gene expressions on T-reg results in the impaired suppressor function of T-reg, and eventually in the breakdown of self-tolerance.     

Increased number of regulatory T cells (T-regs) in the peripheral blood of patients with Her-2/neu-positive early breast cancer

Background

Although progress has been made in establishing prognostic factors in breast cancer, there remains an urgent need for better prognostic and predictive scores for patients with early breast cancer. The important role of the immune system in controlling cancer progression is widely accepted. Regulatory T cells (T-regs) constitute a specialized T cell subset, which play an essential role in sustaining self-tolerance by negatively regulating immune responses. Increased frequencies of T-regs have been reported in the micromilieu of a variety of malignancies including breast cancer. However, little is known about the role of T-regs in the peripheral blood of cancer patients.

Methods

We analyzed T-reg numbers in the peripheral blood of 292 patients with newly diagnosed early breast cancer by flow cytometry (CD4⁺CD25⁺CD127^low cells) prior to planned breast surgery.

Results

Absolute T-reg numbers/μl varied from 4 to 212/μl. No difference could be detected in T-reg numbers between nodal negative and nodal positive, well and poorly differentiated or small and locally advanced cancers. However, T-reg numbers of Her-2/neu-positive patients were higher than in samples from patients with hormone receptor positive, Her-2/neu-negative cancers. In contrast, numbers of T-regs were not increased in triple negative patients. In addition, T-reg numbers were higher in patients with invasive ductal carcinomas as compared to invasive lobular cancers.

Conclusions

Increased numbers of circulating T-regs may contribute to the higher metastatic potential of Her-2/neu-positive cells. A potential role as a prognostic or predictive parameter is currently being analyzed in a larger cohort of patients with sufficient follow-up.     

Aetiopathogenesis of autoimmune hepatitis

The histological hallmark of autoimmune hepatitis（AIH） is a dense portal mononuclear cell infiltrate that invades the surrounding parenchyma and comprises T and B lymphocytes,macrophages,and plasma cells.An unknown but powerful stimulus must be promoting the formation of this massive inflammatory cellular reaction that is likely to initiate and perpetuate liver damage.An autoimmune attack can follow different pathways to inflict damage on hepatocytes.Liver damage is likely to be orchestrated by CD4^＋ T lymphocytes recognizing an autoantigenic liver peptide.To trigger an autoimmune response,the peptide must be embraced by an HLA class Ⅱ molecule and presented to naive CD4^＋ T helper（Th0） cells by professional antigen presenting cells,with the co-stimulation of ligand-ligand fostering interaction between the two cells.Th0 cells become activated,differentiate into functional phenotypes according to the cytokines prevailing in the microenvironment and the nature of the antigen,and initiate a cascade of immune reactions determined by the cytokines produced by the activated T cells.Th1 cells,arising in the presence of the macrophage-derived interleukin（IL） -12,secrete mainly IL-2 and interferon-gamma（IFN-γ）,which activate macrophages,enhance expression of HLA classⅠ（increasing liver cell vulnerability to a CD8^＋ T cell cytotoxic attack）,and induce expression of HLA class Ⅱ molecules on hepatocytes.Th2 cells,which differentiate from Th0 if the microenvironment is rich in IL-4,produce mainly IL-4,IL-10,and IL-13 which favour autoantibody production by B lymphocytes.Physiologically,Th1 and Th2 antagonize each other.Th17 cells,a recently described population,arise in the presence of transforming growth factor beta（TGF-β） and IL-6 and appear to have an important effector role in inflammation and autoimmunity.Theprocess of autoantigen recognition is strictly controlled by regulatory mechanisms,such as those exerted by CD4^＋CD25^＋ regulatory T cells,which derive from Th0 in the presen     

IL-6 controls Th17 immunity in vivo by inhibiting the conversion of conventional T cells into Foxp3+ regulatory T cells

The conditions leading to the induction of adaptive Foxp3⁺ regulatory T cells (T-regs) from peripheral T cells in vivo are incompletely understood. Here, we show that unresponsiveness of T cells to IL-6 by T cell-selective deletion of gp130 or immunization of wild-type mice with antigen in incomplete Freund's adjuvant (IFA), which fails to induce IL-6, promotes the conversion of peripheral CD4⁺ T cells into adaptive Foxp3⁺ T-regs. Thus, both T cell-conditional gp130 knockout (KO) mice immunized with MOG35-55 in complete Freund's adjuvant (CFA) and wild-type mice immunized with MOG35-55 in IFA develop overwhelming antigen-specific T-reg responses and are protected from experimental autoimmune encephalomyelitis (EAE). Depletion of T-regs restores T helper (Th)17 responses and clinical EAE in MOG/CFA-immunized T cell-conditional gp130 KO mice, but not in MOG/IFA-immunized wild-type mice. We conclude that in the absence of T-regs, IL-6 signaling is dispensable for the induction of Th17 cells, and alternative pathways exist to induce Th17 cells and EAE in the absence of IL-6 signaling. However, IL-6 signaling is dominant in inhibiting the conversion of conventional T cells into Foxp3⁺ T-regs in vivo, and in the absence of IL-6 signaling, no other cytokine can substitute in inhibiting T-reg conversion. These data identify IL-6 as an important target to modulate autoimmune responses and chronic inflammation.     

Tim-3 is an inducible human natural killer cell receptor that enhances interferon gamma production in response to galectin-9

NK-cell function is regulated by the integration of signals received from activating and inhibitory receptors. Here we show that a novel immune receptor, T-cell Ig and mucin-containing domain-3 (Tim-3), is expressed on resting human NK cells and is up-regulated on activation. The NK92 NK-cell line engineered to overexpress Tim-3 showed a marked increase in IFN-γ production in the presence of soluble rhGal-9 or Raji tumor cells engineered to express Gal-9. The Tim-3(+) population of low-dose IL-12/IL-18-activated primary NK cells significantly increased IFN-γ production in response to soluble rhGal-9, Gal-9 presented by cell lines, and primary acute myelogenous leukemia (AML) targets that endogenously express Gal-9. This effect is highly specific as Tim-3 Ab blockade significantly decreased IFN-γ production, and Tim-3 cross-linking induced ERK activation and degradation of IκBα. Exposure to Gal-9-expressing target cells had little effect on CD107a degranulation. Reconstituted NK cells obtained from patients after hematopoietic cell transplantation had diminished expression of Tim-3 compared with paired donors. This observation correlates with the known IFN-γ defect seen early posttransplantation. In conclusion, we show that Tim-3 functions as a human NK-cell coreceptor to enhance IFN-γ production, which has important implications for control of infectious disease and cancer.     

Tim-3/galectin-9 signaling pathway mediates T-cell dysfunction and predicts poor prognosis in patients with hepatitis B virus-associated hepatocellular carcinoma

The interaction between T cell immunoglobulin- and mucin-domain-containing molecule (Tim-3) expressed on T helper 1 (Th1) cells, and its ligand, galectin-9, negatively regulates Th1-mediated immune responses. However, it is poorly understood if and how the Tim-3/galectin-9 signaling pathway is involved in immune escape in patients with hepatocellular carcinoma (HCC). Here we studied the expression, function, and regulation of the Tim-3/galectin-9 pathway in patients with hepatitis B virus (HBV)-associated HCC. We detected different levels of galectin-9 expression on antigen-presenting cell (APC) subsets including Kupffer cells (KCs), myeloid dendritic cells (DCs), and plasmacytoid DCs in HCC. The highest galectin-9 expression was on KCs in HCC islets, not in the adjacent tissues. Furthermore, Tim-3 expression was increased on CD4(+) and CD8(+) T cells in HCC as compared to the adjacent tissues, and Tim-3(+) T cells were replicative senescent and expressed surface and genetic markers for senescence. Interestingly, tumor-infiltrating T-cell-derived interferon (IFN)-γ stimulated the expression of galectin-9 on APCs in the HCC microenvironment. Immunofluorescence staining revealed a colocalization of Tim-3(+) T cells and galectin-9(+) KCs in HCC. Functional studies demonstrated that blockade of the Tim-3/galectin-9 signaling pathway importantly increased the functionality of tumor-infiltrating Tim-3(+) T cells as shown by increased T-cell proliferation and effector cytokine production. Finally, we show that the numbers of Tim-3(+) tumor-infiltrating cells were negatively associated with patient survival. Conclusion: Our work demonstrates that the Tim-3/galectin-9 signaling pathway mediates T-cell senescence in HBV-associated HCC. The data suggest that this pathway could be an immunotherapeutic target in patients with HBV-associated HCC. (HEPATOLOGY 2012).     

Impairment of CD4(+)CD25(+) regulatory T-cells in autoimmune liver disease

BACKGROUND/AIMS: CD4(+) lymphocytes constitutively expressing the IL-2-receptor alpha-chain (CD25) regulate the activation of CD4 and CD8 autoreactive T-cells by suppressing their proliferation and effector function. The aim of this study is to: (1) measure the percentage of CD4(+)CD25(+) T-cells (T-regs) in patients with autoimmune liver disease at presentation and during remission, (2) correlate their frequency with disease activity, (3) determine their ability to expand and (4) to inhibit interferon-gamma (IFNgamma) production by CD4(+)CD25- T-cells. METHODS: 41 patients were studied. Percentage of T-regs was determined on peripheral blood mononuclear cells (PBMCs) by triple-colour flow cytometry; their ability to expand by exposing PBMCs to a T-cell expander (CD3/CD28 Dynabeads); their immunoregulatory function by measuring their ability to suppress IFNgamma production by CD4(+)CD25(-) T-cells. RESULTS: T-regs were significantly less in patients than in controls, and at diagnosis than during remission. Their percentage was inversely correlated with titres of anti-liver kidney microsomal and soluble liver antigen autoantibodies. T-regs ability to expand was significantly lower in patients than in controls, but that to suppress IFNgamma production by CD4(+)CD25(-) T-cells was maintained. CONCLUSIONS: Decreased T-regs numbers and ability to expand may favour the emergence of liver-targeted autoimmunity, despite preserved suppressor function. Treatment should aim at increasing T-regs number.     

Immunosuppression during active tuberculosis is characterized by decreased interferon- gamma production and CD25 expression with elevated forkhead box P3, transforming growth factor- beta , and interleukin-4 mRNA levels

The balance between effector and regulatory responses after Mycobacterium tuberculosis infection may dictate outcome and progression to active disease. We investigated effector and regulatory T cell responses in bacille Calmette-Guerin (BCG)-stimulated peripheral blood mononuclear cells and whole blood cultures from persons with active tuberculosis (TB), persons with TB at the end of 6 months of treatment, and healthy control subjects with latent TB infection. All 3 groups displayed BCG-induced increases in effector and regulatory T cell phenotypes as defined by CD4(+)CD25(lo) and CD4(+)CD25(hi) T cells, respectively. In case patients with active disease, BCG stimulation induced the lowest increase of CD25, CD4(+)CD25(hi), CTLA-4, and interferon- gamma . However, these case patients expressed the highest mRNA levels of forkhead box P3, transforming growth factor (TGF)- beta , and interleukin (IL)-4 and a lower T-bet : GATA-3 ratio. There were no significant differences in IL-4 delta 2, IL-10, or TGF- beta receptor-II mRNA expression between groups. Together, these results suggest that immunosuppression seen after mycobacterial stimulation in case patients with active TB is associated with naturally occurring regulatory T cells.     

Reduced Tim-3 expression on human T-lymphotropic virus type I (HTLV-I) Tax-specific cytotoxic T lymphocytes in HTLV-I infection

T cell immunoglobulin and mucin domain-containing molecule-3 (Tim-3) and programmed cell death-1 (PD-1) are T cell exhaustion molecules. We investigated the expression of Tim-3 and PD-1 in human T-lymphotropic virus type I (HTLV-I) infection. Tim-3 expression, but not PD-1 expression, was reduced on CD4(+) and CD8(+) T cells of HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP) patients and HTLV-I carriers as compared with healthy controls. Tim-3 expression was also reduced in HTLV-I Tax-specific cytotoxic T lymphocytes (CTLs) as compared with cytomegalovirus-specific CTLs. Tim-3(+), but not PD-1(+), Tax-specific CTLs produced less interferon-γ and exhibited low cytolytic activity. However, we observed no difference in the expression of Tim-3 or cytolytic activity between Tax-specific CTLs of HAM/TSP patients or carriers. Moreover, HTLV-I-infected CD4(+) T cells showed decreased Tim-3 expression. These data suggest that Tim-3 expression is reduced in HTLV-I infection and that a high number of Tim-3(-) HTLV-I-specific CTLs preserves their cytolytic activity, thereby controlling viral replication.     

Identification of the CD16low CD56low CD38pos Natural Killer Cell as a Key Subset in Patients with Multiple Myeloma

Background: Natural killer (NK) cells are classified as innate immune cells which can directly recognize and kill tumor cells without antigen sensitization. NK cell-based adoptive immunotherapy for blood malignancies has attracted more attention in recent years. Objective: To analyze different NK cell subsets in the peripheral blood and bone marrow (BM) of patients with multiple myeloma (MM). Methods: Using flow cytometry we analyzed: (i) the distribution of distinct NK cell subpopulations (i.e. CD16low CD56low, CD16pos CD56high, CD16neg CD56high, CD16high CD56low, CD16neg CD56low, CD16low CD56low CD38pos) in the BM from MM patients at distinct disease stages. (ii) the expression of NKG2D, DNAM-1 and NKp30, and (iii) the expression of CD107a in CD16low CD56low CD38pos and CD16low CD56low CD38neg NK cells subsets. Results: CD16low CD56low CD38pos was the dominant subset in BM from patients with MM at the CR stage with a decreased expression of NKp30. CD16low CD56low CD38pos subset showed a higher proportion of CD107a expression compared to CD16low CD56low CD38neg cells. In vitro experiments indicated that the CD16low CD56low CD38pos NK cell subset possesses more cytotoxicity than CD16low CD56low CD38neg NK cells. Conclusion: Our data suggest that CD16low CD56low CD38pos NK cells may reflect as an effector population with the potential therapeutic target in patients with MM. This group of cells may be useful for adoptive immunotherapy in MM in the future.     

Contrasting acute graft-versus-host disease effects of Tim-3/galectin-9 pathway blockade dependent upon the presence of donor regulatory T cells

T-cell immunoglobulin mucin-3 (Tim-3) is expressed on pathogenic T cells, and its ligand galectin-9 (gal-9) is up-regulated in inflamed tissues. When Tim-3(+) T cells encounter high gal-9 levels, they are deleted. Tim-3 is up-regulated on activated T cells during GVHD. Inhibition of Tim-3/gal-9 binding by infusion of a Tim-3-Ig fusion protein or Tim-3(-/-) donor T cells increased T-cell proliferation and GVHD lethality. When the Tim-3/gal-9 pathway engagement was augmented using gal-9 transgenic recipients, GVHD lethality was slowed. Together, these data indicate a potential for modulating this pathway to reduce disease by increasing Tim-3 or gal-9 engagement. Paradoxically, when Tim-3/gal-9 was inhibited in the absence of donor T-regulatory cells (Tregs), GVHD was inhibited. GVHD reduction was associated with decreased colonic inflammatory cytokines as well as epithelial barrier destruction. CD25-depleted Tim-3(-/-) donor T cells underwent increased activation-induced cell death because of increased IFN-γ production. To our knowledge, these studies are the first to show that although the absence of Tim-3/gal-9 pathway interactions augments systemic GVHD, concurrent donor Treg depletion paradoxically and surprisingly inhibits GVHD. Thus, although donor Tregs typically inhibit GVHD, under some conditions, such Tregs actually may contribute to GVHD by reducing activation-induced T-cell death.     

Sequential deregulation of NK cell subset distribution and function starting in acute HIV-1 infection

Natural killer (NK) cells are critical in the first-line defense against viral infections. Chronic HIV-1 infection leads to a perturbation in the NK cell compartment, yet the kinetics of this deregulation and the functional consequences are unclear. Here, we characterized changes in the NK cell compartment longitudinally by multiparameter flow cytometry, starting in acute HIV-1 infection. Acute HIV-1 infection was associated with elevated NK cell numbers, with an expansion of CD3(neg)CD56(dim)CD16(pos) NK cells and an early depletion of CD3(neg)CD56(bright)CD16(neg) NK cells. Ongoing viral replication resulted in a depletion of CD3(neg)CD56(dim)CD16(pos) NK cells with a paralleled increase in functionally anergic CD3(neg)CD56(neg)CD16(pos) NK cells, accompanied by reduced functional activity, as measured by CD107a expression and cytokine secretion. Taken together, these studies demonstrate a sequential impairment of NK cell function with persistent viral replication resulting from a progressive deregulation of NK cell subsets with distinct functional properties.     

Increased population of CD4(+)CD25(high), regulatory T cells with their higher apoptotic and proliferating status in peripheral blood of acute myeloid leukemia patients

PURPOSE: Regulatory T cells (T-reg) that control harmful autoimmune T cells in the periphery may also suppress the immune response against cancer. In this study we investigated the possible involvement of CD4(+)CD25(high) T-reg in the immune impairment of patients with acute myeloid leukemia (AML). EXPERIMENTAL DESIGN: The frequencies and phenotypes of CD4(+)CD25(high) T cells in the peripheral blood of AML patients were determined by flow cytometry. To assess the functional activity of CD4(+)CD25(high) T cells, CD4(+)CD25(high), and CD4(+)CD25(-) T cells were sorted from peripheral blood mononuclear cells with FACS Vantage. The immunoregulatory properties of CD4(+)CD25(high) and CD4(+)CD25(-) T cells were characterized by proliferation assays and cytokine production assays. In addition, the frequency of apoptotic and proliferating cells in CD4(+)CD25(high) T cells were respectively evaluated by 7AAD and ki67 binding cells using flow cytometry. RESULTS: Compared with healthy controls, AML patients had a higher proportion of CD4(+)CD25(high) T cells in peripheral blood. These cells were CD45-RA(-), CD69(-), CD45-RO(+), CD95(+), and intercellular CTLA-4(+), and secreted low levels of TNF-alpha and IL-10, but no IL-2, IL-4, IL-5, and IFN-gamma. They inhibited the proliferation and cytokine production (IL-2, IFN-gamma) of CD4(+)CD25(-) T cells, but improved IL-10 production under the co-culture of both subsets with stimulation, thus behaving as T-reg. Notably, CD4(+)CD25(high) T cells in AML patients presented significantly higher apoptosis and proliferation than that of healthy individuals. CONCLUSIONS: The frequency of CD4(+)CD25(high) T-reg in peripheral blood in AML patients is significantly higher when compared with healthy individuals, likely due to the increasing proliferation of CD4(+)CD25(high) T cells.