The majority of patients with acute myeloid leukemia will relapse, and older patients often fail to achieve remission with induction chemotherapy. We explored the possibility that leukemic ...suppression of innate immunity might contribute to treatment failure. Natural killer cell phenotype and function was measured in 32 consecutive acute myeloid leukemia patients at presentation, including 12 achieving complete remission. Compared to 15 healthy age-matched controls, natural killer cells from acute myeloid leukemia patients were abnormal at presentation, with downregulation of the activating receptor NKp46 (P=0.007) and upregulation of the inhibitory receptor NKG2A (P=0.04). Natural killer cells from acute myeloid leukemia patients had impaired effector function against autologous blasts and K562 targets, with significantly reduced CD107a degranulation, TNF-α and IFN-γ production. Failure to achieve remission was associated with NKG2A overexpression and reduced TNF-α production. These phenotypic and functional abnormalities were partially restored in the 12 patients achieving remission. In vitro co-incubation of acute myeloid leukemia blasts with natural killer cells from healthy donors induced significant impairment in natural killer cell TNF-α and IFN-γ production (P=0.02 and P=0.01, respectively) against K562 targets and a trend to reduced CD107a degranulation (P=0.07). Under transwell conditions, the inhibitory effect of AML blasts on NK cytotoxicity and effector function was still present, and this inhibitory effect was primarily mediated by IL-10. These results suggest that acute myeloid leukemia blasts induce long-lasting changes in natural killer cells, impairing their effector function and reducing the competence of the innate immune system, favoring leukemia survival.
A subset of regulatory B cells (Bregs) in mice negatively regulate T-cell immune responses through the secretion of regulatory cytokines such as IL-10 and direct cell-cell contact and have been ...linked to experimental models of autoimmunity, inflammation, and cancer. However, the regulatory function of Bregs in human disease is much less clear. Here we demonstrate that B cells with immunoregulatory properties are enriched within both the CD19+IgM+CD27+ memory and CD19+CD24hiCD38hi transitional B-cell subsets in healthy human donors. Both subsets suppressed the proliferation and interferon-γ production of CD3/CD28-stimulated autologous CD4+ T cells in a dose-dependent manner, and both relied on IL-10 secretion as well as cell-cell contact, likely mediated through CD80 and CD86, to support their full suppressive function. Moreover, after allogeneic stem cell transplantation, Bregs from patients with chronic graft-versus-host disease (cGVHD) were less frequent and less likely to produce IL-10 than were Bregs from healthy donors and patients without cGVHD. These findings suggest that Bregs may be involved in the pathogenesis of cGVHD and support future investigation of regulatory B cell–based therapy in the treatment of this disease.
•Human IgM memory B cells possess immunoregulatory properties analogous to transitional B cells.•IL-10–producing B cells are deficient in cGVHD.
Cord blood (CB) offers a number of advantages over other sources of hematopoietic stem cells, including a lower rate of chronic graft-versus-host disease (cGVHD) in the presence of increased HLA ...disparity. Recent research in experimental models of autoimmunity and in patients with autoimmune or alloimmune disorders has identified a functional group of interleukin-10 (IL-10)-producing regulatory B cells (Bregs) that negatively regulate T-cell immune responses. At present, however, there is no consensus on the phenotypic signature of Bregs, and their prevalence and functional characteristics in CB remain unclear. Here, we demonstrate that CB contains an abundance of B cells with immunoregulatory function. Bregs were identified in both the naive and transitional B-cell compartments and suppressed T-cell proliferation and effector function through IL-10 production as well as cell-to-cell contact involving CTLA-4. We further show that the suppressive capacity of CB-derived Bregs can be potentiated through CD40L signaling, suggesting that inflammatory environments may induce their function. Finally, there was robust recovery of IL-10–producing Bregs in patients after CB transplantation, to higher frequencies and absolute numbers than seen in the peripheral blood of healthy donors or in patients before transplant. The reconstituting Bregs showed strong in vitro suppressive activity against allogeneic CD4+ T cells, but were deficient in patients with cGVHD. Together, these findings identify a rich source of Bregs and suggest a protective role for CB-derived Bregs against cGVHD development in CB recipients. This advance could propel the development of Breg-based strategies to prevent or ameliorate this posttransplant complication.
•Cord blood is a rich source of B cells with immunoregulatory function.•IL-10–producing B cells may protect against cGVHD after cord blood transplantation.
Tyrosine kinase inhibitors (TKIs) have significant off-target multikinase inhibitory effects. We aimed to study the impact of TKIs on the in vivo B-cell response to vaccination. Cellular and humoral ...responses to influenza and pneumococcal vaccines were evaluated in 51 chronic phase chronic myeloid leukemia (CML) patients on imatinib, or second-line dasatinib and nilotinib, and 24 controls. Following vaccination, CML patients on TKI had significant impairment of IgM humoral response to pneumococcus compared with controls (IgM titer 79.0 vs 200 U/mL, P = .0006), associated with significantly lower frequencies of peripheral blood IgM memory B cells. To elucidate whether CML itself or treatment with TKI was responsible for the impaired humoral response, we assessed memory B-cell subsets in paired samples collected before and after imatinib therapy. Treatment with imatinib was associated with significant reductions in IgM memory B cells. In vitro coincubation of B cells with plasma from CML patients on TKI or with imatinib, dasatinib, or nilotinib induced significant and dose-dependent inhibition of Bruton's tyrosine kinase and indirectly its downstream substrate, phospholipase-C-γ2, both important in B-cell signaling and survival. These data indicate that TKIs, through off-target inhibition of kinases important in B-cell signaling, reduce memory B-cell frequencies and induce significant impairment of B-cell responses in CML.
•TKIs impair B-cell immune responses in CML through off-target inhibition of kinases important for B-cell signaling.•Our results call for close monitoring of patients on TKI to assess the long-term impact of impaired B-cell function.
In 2009 the declaration by the World Health Organization of a global pandemic of influenza-H1N1 virus led to a vaccination campaign to ensure protection for immunocompromised patients. The goal of ...this study was to determine the efficacy of the 2009 H1N1 vaccine in patients with hematologic malignancies.
We evaluated humoral and cellular immune responses to 2009 H1N1 vaccine in 97 adults with hematologic malignancies and compared these responses with those in 25 adult controls. Patients received two injections of vaccine 21 days apart and the controls received one dose. Antibody titers were measured using a hemagglutination-inhibition assay on days 0, 21 and 49 after injection of the first dose. Cellular immune responses to H1N1 were determined on days 0 and 49.
By day 21 post-vaccination, protective antibody titers of 1:32 or more were seen in 100% of controls compared to 39% of patients with B-cell malignancies (P<0.001), 46% of allogeneic stem cell transplant recipients (P<0.001) and 85% of patients with chronic myeloid leukemia (P=0.086). After a second dose, seroprotection rates increased to 68%, (P=0.008), 73%, (P=0.031), and 95% (P=0.5) in patients with B-cell malignancies, after allogeneic stem cell transplantation and with chronic myeloid leukemia, respectively. On the other hand, T-cell responses to H1N1 vaccine were not significantly different between patients and controls.
These data demonstrate the efficacy of H1N1 vaccine in most patients with hematologic malignancies and support the recommendation for the administration of two doses of vaccine in immunocompromised patients. These results may contribute towards the development of evidence-based guidelines for influenza vaccination in such patients in the future.
Chronic graft-versus-host disease (cGvHD) remains a major complication of allogeneic hematopoietic stem cell transplantation (HSCT). A number of studies support a role for B cells in the pathogenesis ...of cGvHD. In this study, we report the presence of an expanded population of CD19+CD21- B cells with features of exhaustion in the peripheral blood of patients with cGvHD. CD21- B cells were significantly increased in patients with active cGvHD compared to patients without cGvHD and healthy controls (median 12.2 versus 2.12 versus 3%, respectively;
< 0.01). Compared with naïve (CD27-CD21+) and classical memory (CD27+CD21+) B cells, CD19+CD21- B cells in cGvHD were CD10 negative, CD27 negative and CD20hi, and exhibited features of exhaustion, including increased expression of multiple inhibitory receptors such as FCRL4, CD22, CD85J, and altered expression of chemokine and adhesion molecules such as CD11c, CXCR3, CCR7, and CD62L. Moreover, CD21- B cells in cGvHD patients were functionally exhausted and displayed poor proliferative response and calcium mobilization in response to B-cell receptor triggering and CD40 ligation. Finally, the frequencies of circulating CD21- B cells correlated with cGvHD severity in patients after HSCT. Our study further characterizes B cells in chronic cGVHD and supports the use of CD21-CD27-CD10- B cell frequencies as a biomarker of disease severity.
The transcriptional programs that guide lymphocyte differentiation depend on the precise expression and timing of transcription factors (TFs). The TF BACH2 is essential for T and B lymphocytes and is ...associated with an archetypal super-enhancer (SE). Single-nucleotide variants in the BACH2 locus are associated with several autoimmune diseases, but BACH2 mutations that cause Mendelian monogenic primary immunodeficiency have not previously been identified. Here we describe a syndrome of BACH2-related immunodeficiency and autoimmunity (BRIDA) that results from BACH2 haploinsufficiency. Affected subjects had lymphocyte-maturation defects that caused immunoglobulin deficiency and intestinal inflammation. The mutations disrupted protein stability by interfering with homodimerization or by causing aggregation. We observed analogous lymphocyte defects in Bach2-heterozygous mice. More generally, we observed that genes that cause monogenic haploinsufficient diseases were substantially enriched for TFs and SE architecture. These findings reveal a previously unrecognized feature of SE architecture in Mendelian diseases of immunity: heterozygous mutations in SE-regulated genes identified by whole-exome/genome sequencing may have greater significance than previously recognized.
An array of monopole antennas over a ground plane that radiates a directive lobe in the end-fire direction are described in this paper. The design uses the rigorous method described by Drouet et al. ...2008 in order to synthesize the radiation through the strong cumulative coupling between the monopoles. A gain higher than 20 dB was achieved in the end-fire direction over a 4.5% bandwidth. However, the antenna has been tilted in order to compensate the beam deviation caused by the edge diffraction. A prototype with 12 elements has been manufactured in order to validate the antenna principle and the whole antenna is successfully measured. The prototype was studied with the software CST-Microwave Studio and the feed network has been designed with Agilent ADS.
Background: Immune thrombocytopenia (ITP) is an autoimmune disorder characterized by isolated low platelet count and a skewed proinflammatory Th1/Th17 profile. However, little is known about the ...involvement of CD8+ cytotoxic T cells in ITP pathophysiology and whether they are regulated by regulatory T cells (Treg). Immunosuppressive therapy has been the mainstay treatment in ITP. More recently, Thrombopoietin receptor agonists (TPO-RA); Romiplostim (Romi) and Eltrombopag (EPAG), have been increasingly used to stimulate megakaryocytopoiesis to produce more platelets. TPO-RAs are reported to induce complete remission in up to 30% of cases, with limited understanding of their impact on the immune system. Here we describe changes in T cell subsets in patients with ITP: how these changes are affected by disease activity and how TPO-RA may induce remission through modulating the immune system.
Methods: Multi-color flow cytometric panels were designed to characterize peripheral blood T cell subsets, including CD8+ T cell and Treg subsets, phenotypically as well as functionally through intracellular cytokine expression. To determine whether CD8+ cells were platelet specific, an IFNγ ELISpot assay was performed using platelets from a healthy donor and PBMC from both HC and patients. Forty patients with ITP were included: 13 were on Romi, 11 on EPAG and 16 on no treatment at the time of analysis. Of these 40 patients, 15 patients had active disease (AD) (platelet-count less than 30 x 109/L) and 25 had stable disease (SD) (> 30 x 109/L). These patients were compared with 26 age and gender-matched healthy controls (HC). Data were presented as median values; Mann Whitney U and Kruskal Wallis tests were used with Dunn's multiple comparisons correction; a P value of < 0.05 was considered significant.
Results: CD4/CD8 T cell ratio was significantly lower in patients compared to HC 1.77 vs. 3.97; P value < 0.001. CD45RA+CD62L- Terminally-differentiated CD8+ T cells were significantly higher in patients compared to HC 66.3% vs. 8.56%; P value < 0.001. This finding was more prominent in AD patients than those with SD 66% vs. 44.4%; P value < 0.05. This effector population is polyfunctional, expressing high levels of proinflammatory cytokines including TNFα, IFNγ and Granzyme B when compared to HC P value < 0.05. Additionally, this population lacks the exhaustion markers PD-1 and Tim-3. Furthermore, these cells were reactive to platelets showing higher IFNγ-producing cells when co-cultured with platelets.
CD3+CD4+CD25hiCD127lo Treg frequency did not differ between patients and HC P value>0. 05. Treg functionality was preserved in these patients; no important changes were observed in their capacity to express interlukin2 intracellularly, nor in the cell surface receptor (CD25) P value > 0. 05. However, Tregs were significantly lower in AD patients with compared to SD patients 2.32% vs. 4.46%; P value < 0.05. Treg function is interactive with other T cell subsets and depends on its relative abundance in relation to other subsets; The Treg/effector CD8+ T cell ratio was significantly lower in patients compared to HC 0.06 vs. 0.16; P value < 0.01 and was also significantly lower in AD compared to SD patients 0.03 vs. 0.09 ; P value < 0.05.
EPAG-treated patients had a significantly lower effector CD8+ T cells compared to Romi-treated patients 42.4% vs 76.8%; P value <0.01. Although EPAG did not have a direct effect on the frequency of Treg, the Treg/effector CD8+ T cell ratio was significantly lower than that in patients on Romi 0.04 vs. 0.11; P value < 0.05 because of the CD8+.T cell difference. The Treg/effector CD8+ T cell ratio in EPAG-treated patients was comparable to the ratio of HC 0.11 vs. 0.16; P value > 0.05.
Conclusion: While Th1/Th2 cell ratio is often considered as driving ITP, these results demonstrate the involvement of cytokine secreting effector CD8+ T cells in the disease pathogenesis. The imbalance in immune tolerance is also highlighted in the form of a significant reduction in the Treg/effector CD8 T cell ratio. The differences seen in T cell subsets between EPAG- and Romi-treated patients suggest the potential for an additional, differential immunomodulatory effect between the two agents which is currently being explored.
Acknowledgment: The authors wish to thank Prof James B Bussel for his insightful comments and support of this work.
Cooper:Amgen, Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees.
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