B-cell frequencies and immunoregulatory phenotypes in myeloproliferative neoplasms: Influence of ruxolitinib, interferon-α2, or combination treatment.

OBJECTIVE: Given a proposed role for PD-L1+ and IL-10-producing B-cell subsets in promoting certain cancers, we sought to characterize the frequency and phenotype of B cells in patients with chronic myeloproliferative neoplasms (MPNs) and the influence of ruxolitinib and interferon-α2 therapy. METHODS: We analyzed B-cell frequencies and phenotype in patients with MPNs (n = 107), before and during treatment with ruxolitinib (n = 29), interferon-α2 (n = 21), or the two drugs in combination (COMBI; n = 42) and healthy donors (HDs; n = 52) using flow cytometry. RESULTS: Myelofibrosis patients had lower lymphocyte counts and proportions of B cells than patients with essential thrombocythemia or polycythemia vera and HDs. The B-cell count correlated inversely with JAK2-V617F allele burden and spleen size and increased after ruxolitinib or COMBI treatment. The proportions of PD-L1+ B cells and PD-1+ B cells were significantly higher in patients with myelofibrosis or polycythemia vera than in HDs and decreased during ruxolitinib and COMBI treatment. The proportions of TNF-α+ and IL-6+ B cells were elevated in myelofibrosis patients. The proportion of IL-6+ B cells decreased, and the proportion of IL-10+ B cells increased during ruxolitinib treatment. CONCLUSION: B-cell frequency and phenotype were altered in MPN patients. Ruxolitinib therapy had marked effects on both frequency and phenotype.

Interferon-α induces marked alterations in circulating regulatory T cells, NK cell subsets, and dendritic cells in patients with JAK2V617F-positive essential thrombocythemia and polycythemia vera.

Long-term therapy with IFN-α2 is associated with sustained major molecular remissions in JAK2-positive ET and PV. The efficacy of IFN-α2 may be partly mediated by modulation of immune cells, which was investigated in twenty patients with ET (n = 6) and PV (n = 14). The frequency of CD4(+) CD25(+) Foxp3(+) T cells was significantly increased during IFN-α2 treatment in all patients (P < 0.0001). A significant expansion of the CD56(bright) NK cells (P = 0.0002) and a concomitant decrease in the frequency of CD56(dim) NK cells (P < 0.0001) were also detected. Myeloid DCs (mDCs) and plasmacytoid DCs (pDCs) were studied in nine patients, and decreased frequencies of both cell types were observed during the course of treatment. On both mDCs and pDCs, HLA-ABC expression was upregulated (P = 0.003), but decreasing expression levels of HLA-DR was detected on mDCs. The expression of CD40 (P = 0.002), CD83 (P = 0.03), and CD86 (P = 0.01) increased, but was confined to pDCs. Furthermore, PD-L1 expression was reduced on mDC (P = 0.003) and increased on pDCs (P = 0.02). No significant correlations were found between the changes in immune cells and hematological or molecular responses achieved in our cohort of patients. So forth, it remains to be revealed whether the profound changes in circulating immune cells contribute to the beneficial effects of long-term IFN-α2 treatment in some patients.

Expansion of circulating CD56bright natural killer cells in patients with JAK2-positive chronic myeloproliferative neoplasms during treatment with interferon-α.

In recent years, major molecular remissions have been observed in patients with JAK2-positive chronic myeloproliferative neoplasms (MPNs) after therapy with IFN-α. IFN-α is known to have altering effects on immune cells involved in immune surveillance and might consequently enhance anti-tumor immune response against the JAK2-mutated clone. The objective of this study was to investigate circulating levels and phenotype of natural killer cells in 29 JAK2-positive MPN patients during IFN-α treatment. Furthermore, functional studies of NK cells upon target-cell recognition and cytokine stimulation were performed. The CD56(bright) and CD56(dim) NK cell subtypes display different properties in terms of cytokine production and cytotoxicity, respectively. Our results show a significant increase in the proportion of CD56(bright) NK cells and a decreasing CD56(dim) population during treatment with IFN-α compared to patients that are untreated, treated with hydroxyurea and healthy controls, P < 0.0001. Furthermore, an overall increase in cytokine-dependent (IL-12 and IL-15) IFN-γ expression by CD56(dim) NK cells during IFN-α treatment was observed. In contrast, our data indicate a compromised NK cell response to target-cell recognition during treatment with IFN-α in four patients. We also report low levels of circulating NK cells in untreated patients compared to healthy donors, patients treated with hydroxyurea and IFN-α, P = 0.02. Based on our findings, one might speculate whether treatment with IFN-α skews the human NK population toward a helper type that may assist in CD8(+) T cell priming in lymphoid tissues at the expense of their immediate cytotoxic functions in peripheral blood and tissues.

High frequencies of circulating memory T cells specific for calreticulin exon 9 mutations in healthy individuals.

Mutations in exon 9 of the calreticulin gene (CALR) frequently occur in patients with chronic myeloproliferative neoplasms (MPN). Patients exhibit spontaneous cellular immune responses to epitopes derived from the mutant CALR C-terminus, and CALR-mutant-specific T cells recognize autologous CALR-mutant malignant cells. This study investigated whether CALR-mutant-specific T cells occur naturally in CALRwt MPN-patients and in healthy individuals. Specific immune responses against epitopes in the mutant CALR peptide sequence were detected in both CALRwt MPN-patients and in healthy individuals. Healthy donors displayed more frequent and stronger CALR-mutant specific T-cell responses compared to the responses identified in CALR-mutant MPN-patients. Several T-cell responses were identified in healthy donors directly ex vivo. Importantly, by running functional analyses on live-sorted immune cells from healthy donors, we showed that circulating CALR-mutant-specific immune cells are T-memory cells. These findings suggest, that healthy individuals acquire a CALR exon 9 mutation, but the immune system reacts and clears the mutant cells, and during this reaction generates CALR-mutant specific T-memory cells. We believe that these findings provide the evidence for tumor immune surveillance in MPN.

Statins in the treatment of polycythaemia vera and allied disorders: an antithrombotic and cytoreductive potential?

Thrombohaemorrhagic complications are major clinical problems in the classical chronic Ph-negative myeloproliferative disorders (CMPDs), polycytaemia vera (PV), essential thrombocythaemia (ET) and idiopathic myelofibrosis (IMF), contributing significantly to morbidity and mortality. Pathophysiologically these disorders are characterized by clonal myeloproliferation, myeloaccumulation and a propensity to develop myelofibrosis and neoangiogenesis in both the bone marrow and spleen. Based upon in vitro and in vivo studies of the effects of statins (antithrombotic, antiproliferative, proapoptotic and antiangiogenic), this review focuses on the translation of these effects into potential clinical benefits of statin therapy in patients with CMPDs.

A 7-Gene Signature Depicts the Biochemical Profile of Early Prefibrotic Myelofibrosis.

Recent studies have shown that a large proportion of patients classified as essential thrombocythemia (ET) actually have early primary prefibrotic myelofibrosis (prePMF), which implies an inferior prognosis as compared to patients being diagnosed with so-called genuine or true ET. According to the World Health Organization (WHO) 2008 classification, bone marrow histology is a major component in the distinction between these disease entities. However, the differential diagnosis between them may be challenging and several studies have not been able to distinguish between them. Most lately, it has been argued that simple blood tests, including the leukocyte count and plasma lactate dehydrogenase (LDH) may be useful tools to separate genuine ET from prePMF, the latter disease entity more often being featured by anemia, leukocytosis and elevated LDH. Whole blood gene expression profiling was performed in 17 and 9 patients diagnosed with ET and PMF, respectively. Using elevated LDH obtained at the time of diagnosis as a marker of prePMF, a 7-gene signature was identified which correctly predicted the prePMF group with a sensitivity of 100% and a specificity of 89%. The 7 genes included MPO, CEACAM8, CRISP3, MS4A3, CEACAM6, HEMGN, and MMP8, which are genes known to be involved in inflammation, cell adhesion, differentiation and proliferation. Evaluation of bone marrow biopsies and the 7-gene signature showed a concordance rate of 71%, 79%, 62%, and 38%. Our 7-gene signature may be a useful tool to differentiate between genuine ET and prePMF but needs to be validated in a larger cohort of "ET" patients.

Gene expression profiling with principal component analysis depicts the biological continuum from essential thrombocythemia over polycythemia vera to myelofibrosis.

The recent discovery of the Janus activating kinase 2 V617F mutation in most patients with polycythemia vera (PV) and half of those with essential thrombocythemia (ET) and primary myelofibrosis (PMF) has favored the hypothesis of a biological continuum from ET over PV to PMF. We performed gene expression profiling of whole blood from control subjects (n = 21) and patients with ET (n = 19), PV (n = 41), and PMF (n = 9) using DNA microarrays. Applying an unsupervised method, principal component analysis, to search for patterns in the data, we demonstrated a separation of the four groups with biological relevant overlaps between the different entities. Moreover, the analysis separates Janus activating kinase 2-negative ET patients from Janus activating kinase 2-positive ET patients. Functional annotation analysis demonstrates that clusters of gene ontology terms related to inflammation, immune system, apoptosis, RNA metabolism, and secretory system were the most significantly deregulated terms in the three different disease groups. Our results yield further support for the hypothesis of a biological continuum originating from ET over PV to PMF. Functional analysis suggests an important implication of these gene ontology clusters in the pathogenesis of these neoplasms and in disease evolution from ET over PV to PMF.

[Flowcytometric diagnostics of hereditary spherocytosis]. / Flowcytometrisk diagnostik af hereditaer sfaerocytose.

INTRODUCTION: The diagnosis of hereditary spherocytosis (HS) is based upon clinical presentation, typical laboratory findings of haemolysis with an increased mean corpuscular haemoglobin concentration (MCHC) combined with a positive osmotic fragility result. The disorder is caused by structural defects in red cell cytoskeletal proteins. The dye eosin-5'-maleimide (EMA) binds to band three of the red cell membrane. The fluorescence intensity of EMA-labelled red cells can be quantified by flowcytometric analysis. Decreased fluorescence is found in patients with HS. We have evaluated this method by comparing flowcytometric analysis of red cells from patients with HS and patients with other haemolytic disorders. MATERIAL AND METHODS: We included 21 patients with HS and 27 patients with other haemolytic disorders. The red cells were incubated and labelled with EMA followed by flowcytometric analysis measuring the mean-fluorescence-intensity expressed as EMA percentage. RESULTS: Based on the overall results, we assess an EMA percentage threshold of 15 or above to indicate HS. We found a sensitivity of 95% and a specificity of 93%. CONCLUSION: The osmotic fragility test does not have the same high degree of sensitivity and specificity and the test is time-consuming in the laboratory setting. Flowcytometric analysis with quantification of fluorescence intensity of red cells labelled with the EMA dye has proven to be a rapid and user-friendly method available to any laboratory with a flowcytometer. The method has a high sensitivity and specificity and can be recommended as a diagnostic tool for HS.

The mevalonate pathway as a therapeutic target in the Ph-negative chronic myeloproliferative disorders.

The Ph-negative chronic myeloproliferative disorders (CMPDs) polycythaemia vera, essential thrombocytosis and idiopathic myelofibrosis are acquired stem cell disorders, which pathophysiologically are featured by clonal myeloproliferation and accumulation of myeloid cells, the latter being consequent to decreased apoptosis. Myelofibrosis and neoangiogenesis in the bone marrow and spleen are the histopathological hallmarks of idiopathic myelofibrosis but may develop in the other diseases as well. In patients with myelofibrosis elevated levels of circulating CD34+ cells are highly characteristic being partly explained by a proteolytic bone marrow mileu owing to excessive release of various proteases with ensuing extracellular matrix degradation and constitutive mobilisation of CD34+ cells into the peripheral blood. Thrombohaemorrhagic complications are major clinical problems contributing significantly to morbidity and mortality. Based upon in vitro and in vivo studies of the effects of statins (antithrombotic, antiproliferative, antiangiogenic, antiproteolytic) and zoledronic acid (antiproliferative antiproliferative, antiangiogenic, antiproteolytic) this review focusses on the translation of these effects into potential clinical benefits of combinational therapy with these agents in patients with CMPDs.