Antibodies to calnexin and mutated calreticulin are common in human sera.

PURPOSE OF THE STUDY: Calreticulin is an endoplasmic reticulum chaperone protein, which is involved in protein folding and in peptide loading of major histocompatibility complex class I molecules together with its homolog calnexin. Mutated calreticulin is associated with a group of hemopoietic disorders, especially myeloproliferative neoplasms. Currently only the cellular immune response to mutated calreticulin has been described, although preliminary findings have indicated that antibodies to mutated calreticulin are not specific for myeloproliferative disorders. These findings have prompted us to characterize the humoral immune response to mutated calreticulin and its chaperone homologue calnexin. PATIENTS AND METHODS: We analyzed sera from myeloproliferative neoplasm patients, healthy donors and relapsing-remitting multiple sclerosis patients for the occurrence of autoantibodies to wild type and mutated calreticulin forms and to calnexin by enzyme-linked immunosorbent assay. RESULTS: Antibodies to mutated calreticulin and calnexin were present at similar levels in serum samples of myeloproliferative neoplasm and multiple sclerosis patients as well as healthy donors. Moreover, a high correlation between antibodies to mutated calreticulin and calnexin was seen for all patient and control groups. Epitope binding studies indicated that cross-reactive antibodies bound to a three-dimensional epitope encompassing a short linear sequence in the C-terminal of mutated calreticulin and calnexin. CONCLUSION: Collectively, these findings indicate that calreticulin mutations may be common and not necessarily lead to onset of myeloproliferative neoplasm, possibly due to elimination of cells with mutations. This, in turn, may suggest that additional molecular changes may be required for development of myeloproliferative neoplasm.

COVID-19 as a mediator of interferon deficiency and hyperinflammation: Rationale for the use of JAK1/2 inhibitors in combination with interferon.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) elicits an interferon (IFN) deficiency state, which aggravates the type I interferon deficiency and slow IFN responses, which associate with e.g. aging and obesity. Additionally, SARS-CoV-2 may also elicit a cytokine storm, which accounts for disease progression and ultimately the urgent need of ventilator support. Based upon several reports, it has been argued that early treatment with IFN-alpha2 or IFN-beta, preferentially in the early disease stage, may prohibit disease progression. Similarly, preliminary studies have shown that JAK1/2 inhibitor treatment with ruxolitinib or baricitinib may decrease mortality by dampening the deadly cytokine storm, which - in addition to the virus itself - also contributes to multi-organ thrombosis and multi-organ failure. Herein, we describe the rationale for treatment with IFNs (alpha2 or beta) and ruxolitinib emphasizing the urgent need to explore these agents in the treatment of SARS-CoV-2 - both as monotherapies and in combination. In this context, we take advantage of several safety and efficacy studies in patients with the chronic myeloproliferative blood cancers (essential thrombocythemia, polycythemia vera and myelofibrosis) (MPNs), in whom IFN-alpha2 and ruxolitinib have been used successfully for the last 10 (ruxolitinib) to 30 years (IFN) as monotherapies and most recently in combination as well. In the context of these agents being highly immunomodulating (IFN boosting immune cells and JAK1/2 inhibitors being highly immunosuppressive and anti-inflammatory), we also discuss if statins and hydroxyurea, both agents possessing anti-inflammatory, antithrombotic and antiviral potentials, might be inexpensive agents to be repurposed in the treatment of SARS-CoV-2.

Distinguishing myelofibrosis from polycythemia vera and essential thrombocythemia: The utility of enumerating circulating stem cells with aberrant hMICL expression by flow cytometry.

INTRODUCTION: Diagnosing BCR-ABL negative myeloproliferative neoplasms (MPN) may be challenging due to overlapping features and lack of robust discriminatory parameters, especially between essential thrombocythemia (ET) and prefibrotic myelofibrosis (MF). Circulating immature hematopoietic cells are variably present in polycythemia vera (PV), ET, and MF. The C-type lectin hMICL is aberrantly expressed on hematopoietic stem cells in the majority of acute myeloid leukemia patients. However, the hMICL expression in MPN, having varying propensity of leukemic transformation, is unsettled. We hypothesized that enumeration of immature cells by flow cytometry (FCM) could be a discriminatory tool in MPN diagnostics. METHODS: By FCM, we quantified circulating stem cells with aberrant hMICL expression in 39 MPN patients, 10 age-matched controls, and in leukapheresis products from 10 patients with lymphoproliferative neoplasms. The utility of the FCM assay for discriminating MPN entities was evaluated by applying ROC curve analysis. RESULTS: While hMICL was absent in control samples, MF patients had significantly more hMICL+ stem cells (median 15.2%) than PV and ET (0.0%, P = .001 and 0.0%, P = .002, respectively). By ROC curve analysis, the presence of hMICL+ stem cells (>0 cells) in peripheral blood reliably discriminates MF from ET and PV with a sensitivity of 80% and a specificity of 97%. CONCLUSION: Enumeration of circulating hMICL+ stem cells by FCM can discriminate between MPN phenotypes and holds potential for monitoring disease evolution.

The calreticulin (CALR) exon 9 mutations are promising targets for cancer immune therapy.

The calreticulin (CALR) exon 9 mutations are found in ∼30% of patients with essential thrombocythemia and primary myelofibrosis. Recently, we reported spontaneous immune responses against the CALR mutations. Here, we describe that CALR-mutant (CALRmut)-specific T cells are able to specifically recognize CALRmut cells. First, we established a T-cell culture specific for a CALRmut epitope. These specific T cells were able to recognize several epitopes in the CALRmut C terminus. Next, we established a CALRmut-specific CD4+ T-cell clone by limiting dilution. These CD4+ T cells recognized autologous CALRmut monocytes and hematopoietic stem cells, and T-cell recognition of target cells was dependent on the presence of CALR. Furthermore, we showed that the CALRmut response was human leukocyte antigen (HLA)-DR restricted. Finally, we demonstrated that the CALRmut-specific CD4+ T cells, despite their phenotype, were cytotoxic to autologous CALRmut cells, and that the cytotoxicity was mediated by degranulation of the T cells. In conclusion, the CALR exon 9 mutations are targets for specific T cells and thus are promising targets for cancer immune therapy such as peptide vaccination in patients harboring CALR exon 9 mutations.

Myeloproliferative neoplasms and inflammation: whether to target the malignant clone or the inflammatory process or both.

The Philadelphia-negative myeloproliferative neoplasms (MPNs) are clonal disorders involving hematopoietic stem and progenitor cells and are associated with myeloproliferation, splenomegaly and constitutional symptoms. Similar signs and symptoms can also be found in patients with chronic inflammatory diseases, and inflammatory processes have been found to play an important role in the pathogenesis and progression of MPNs. Signal transduction pathways involving JAK1, JAK2, STAT3 and STAT5 are causally involved in driving both the malignant cells and the inflammatory process. Moreover, anti-inflammatory and immune-modulating drugs have been used successfully in the treatment of MPNs. However, to date, many unresoved issues remain. These include the role of somatic mutations that are present in addition to JAK2V617F, CALR and MPL W515 mutations, the interdependency of malignant and nonmalignant cells and the means to eradicate MPN-initiating and -maintaining cells. It is imperative for successful therapeutic approaches to define whether the malignant clone or the inflammatory cells or both should be targeted. The present review will cover three aspects of the role of inflammation in MPNs: inflammatory states as important differential diagnoses in cases of suspected MPN (that is, in the absence of a clonal marker), the role of inflammation in MPN pathogenesis and progression and the use of anti-inflammatory drugs for MPNs. The findings emphasize the need to separate the inflammatory processes from the malignancy in order to improve our understanding of the pathogenesis, diagnosis and treatment of patients with Philadelphia-negative MPNs.

Prevalence and clinical significance of neutropenia discovered in routine complete blood cell counts: a longitudinal study.

BACKGROUND: Neutropenia, defined as an absolute blood neutrophil count (ANC) <1.5 G L(-1) , may accompany a variety of diseases. However, the clinical significance of neutropenia detected in a routine complete blood cell count is poorly understood. METHODS: Using a primary care resource, comprising more than 370 000 individuals, we assessed the association with a number of previously recognized conditions as well as all-cause mortality in the 4 years following the identification of neutropenia. By matching laboratory data with Danish nationwide health registers, risk estimates were assessed. RESULTS: Neutropenia was observed in approximately 1% of all individuals and was associated dose dependently with viral infections, haematological malignancies (but not autoimmune disorders or solid cancers) and mortality. Neutropenia was particularly associated with HIV, acute leukaemias and myelodysplastic syndromes. Odds ratios [95% confidence interval (CI)] for viral infections were 2.32 (1.84-2.91), 2.80 (2.20-3.57) and 4.77 (3.22-7.07) for subnormal (≥1.5-1.8 G L(-1) ), mild (≥1.0-1.5 G L(-1) ) and moderate-severe (≥0.0-1.0 G L(-1) ) neutropenic individuals, respectively (all P < 0.001). Likewise, odds ratios (95% CI) for haematological malignancies were 3.23 (2.35-4.45), 8.69 (6.58-11.47) and 46.03 (33.98-62.35 ), for the same neutropenia levels, respectively (all P < 0.001). Thus, the lower the ANC, the greater the likelihood of these diseases. The relative risk estimates observed for severe neutropenia corresponded to absolute risks of haematological malignancies and mortality from any cause of 40% and >50%, respectively. CONCLUSIONS: Neutropenia is an ominous sign necessitating careful follow-up. The risk estimates presented here support focusing attention to viral diseases and haematological malignancies when neutropenia is observed.

Corrigendum to "Combination therapy with interferon and JAK1-2 inhibitor is feasible. Proof of concept with rapid reduction in JAK2V617F-allele burden in Polycythemia Vera" [Leuk. Res. Rep. 3 (2) (2014) 73-75].

[This corrects the article DOI: 10.1016/j.lrr.2014.05.003.].

Combination therapy with interferon and JAK1-2 inhibitor is feasible: Proof of concept with rapid reduction in JAK2V617F-allele burden in polycythemia vera.

We report a 55 year old woman with post-ET PV for 12 years, who experienced resolution of severe constitutional symptoms within 3 days, a marked reduction in splenomegaly and a rapid decline in the JAK2V617F allele burden during combination therapy with interferon-alpha2a and ruxolitinib. Within 4 weeks the patient achieved complete hematological remission with normalization of peripheral blood counts and within 10 months the JAK2V617F-allele burden was reduced from 90% to 28%. Such a rapid decline in the JAK2V617F allele burden is highly unusual in PV-patients during low-dose IFN-alpha2 monotherapy and this finding warrants a prospective study with combination therapy.

Characterization of blood donors with high haemoglobin concentration.

BACKGROUND AND OBJECTIVES: The literature contains little on the prevalence and causes of high predonation haemoglobin levels among blood donors. This study aimed to characterize and develop an algorithm to manage would-be donors with polycythaemia. MATERIALS AND METHODS: Between November 2009 and November 2011, we offered haematology consultations to blood donors with repeated haemoglobin concentration (Hb) above the WHO limit for polycythaemia vera (PV) (10·2 and 11·5 mm/16·5 and 18·5 g/dl for women and men, respectively). Investigation of such donors included Hb, haematocrit, mean cell volume, erythropoietin, ferritin, platelet count and leucocyte count, JAK2 V617 and JAK2 exon12 analysis, as well as other routine measurements. RESULTS: Among 46 such donors, 39 had a history of smoking, which contributes to erythrocytosis. Two had PV, five had severe hypertension, one of them because of renal artery stenosis, and two had diabetes mellitus. Thus, we found a high morbidity among such donors. Of the 36 others, 30 donated again before May 2012, at which time the Hb was significantly lower. CONCLUSION: We recommend JAK2 V617 and JAK2 exon12 screening and clinical investigation for donors with concurrently high Hb, high haematocrit and iron deficiency. We also recommend that they stop or cut down on smoking to reduce the risk of thrombosis in general. We disqualified 10 of the donors.

Inheritance of the chronic myeloproliferative neoplasms. A systematic review.

This systematic review investigated the inheritance of the classical chronic myeloproliferative neoplasms (MPNs) including polycythemia vera (PV), essential thrombocythemia (ET), primary myelofibrosis (PMF) and chronic myelogenous leukemia (CML). Sixty-one articles were included and provided 135 families with a total of 341 participants distributed to various subtypes of MPN: 50% PV, 23% ET, 14% PMF, 10% CML and 3% non-MPN hematological disorder. Women developed the disease earlier than men (43.1 years vs 47.3 years; p = 0.074), while the general average age of onset was 46 years, notably younger than sporadic cases. The clinical phenotype of the families showed a homogenous (67%) and a heterogeneous (33%) pattern, with the majority being PV-PV pairs (36%) and PV-PMF pairs (17%), respectively. This observation suggests that the susceptibility gene (or genes) is not restricted to one subtype supporting the hypothesis of a mutation in an early multipotent stem cell. Furthermore, a major subgroup of families provided evidence of an autosomal dominant (AD) inheritance with reduced penetrance. This study suggests that the origin of MPNs may occur in at least three different settings: (i) a sporadic, (ii) genetic heterogeneity with polygenetic and environmental impact and (iii) a familial phenotype following an AD inheritance.

Systemic adverse events following rituximab therapy in patients with Graves' disease.

BACKGROUND AND AIM: Rituximab (RTX) therapy has shown promising results in Graves' disease (GD), with or without ophthalmopathy. We examined the occurrence of adverse events in GD patients treated with RTX. SUBJECTS AND METHODS: Ten patients received RTX and methimazole, while 10 patients received methimazole only. Adverse events were recorded, and the presence of circulating immune complexes (CIC) was measured as IgG, IgM and complement component 3 (C3) depositing on normal monocytes following incubation with patient plasma. RESULTS: Five patients had benign infusion-related adverse events at first infusion. Two patients developed a serum sickness-like reaction 11 days after the first RTX-infusion. One of these patients developed diarrhea, raised orosomucoid levels, lowgrade inflammation in colonoscopic biopsies, and iridocyclitis 1 yr later. At day 14, the most pronounced immunoglobulin/ C3-adherent to the test monocytes, indicative of CIC, was observed in the presence of plasma from these 2 patients (p=0.003 to p=0.01 vs asymptomatic patients). A 3rd patient had recurrent fever and symmetric polyarthritis from day 38, and colonoscopy-verified ulcerative colitis at day 68. This patient had the 3rd highest increase in Ig deposition on monocytes by day 14. The arthralgias persisted in 2 of the patients, despite glucocorticoid rescue therapy. CONCLUSIONS: We report articular adverse events in 3 and gastrointestinal symptoms in 2 out of 10 GD patients who received RTX without concurrent immunosupression. The joint symptoms were related to CIC formation.

Sustained major molecular response on interferon alpha-2b in two patients with polycythemia vera.

Quantitative assessment of the JAK2 V617F allele burden during disease evolution and ongoing myelosuppressive treatment is likely to be implemented in the future clinical setting. Interferon alpha has demonstrated efficacy in treatment of both chronic myeloid leukemia and the Philadelphia chromosome negative chronic myeloproliferative disorders. Reductions in the JAK2 V617F allele burden in patients treated with pegylated interferon alpha-2a (Peg-IFN-2a) have been demonstrated, although follow-up was relatively short. We report here the first profound and sustained molecular responses with a JAK2 V617F allele burden below 1.0% in two patients with polycythemia vera treated with interferon alpha-2b (IFN-2b). Discontinuation of IFN-2b in one of the patients was followed by a sustained long-lasting (12 months of follow-up) major molecular response.

A unified definition of clinical resistance/intolerance to hydroxyurea in essential thrombocythemia: results of a consensus process by an international working group.

A widely accepted definition of resistance or intolerance to hydroxyurea (HU) in patients with essential thrombocythemia (ET) is lacking. An international working group (WG) was convened to develop a consensus formulation of clinically significant criteria for defining resistance/intolerance to HU in ET. To this aim, an analytic hierarchy process (AHP), a multiple-attribute decision-making technique, was used. The steps consisted of selecting the candidate criteria for defining resistance/intolerance; identifying the motivations that could influence the preference of the WG for any individual criterion; comparing the candidate criteria in a pair-wise manner; and grading them according their ability to fulfill the motivations. Every step in the model was derived by questionnaires or group discussion. The WG proposed that the definition of resistance/intolerance should require the fulfillment of at least one of the following criteria: platelet count greater than 600,000/micro l after 3 months of at least 2 g/day of HU (2.5 g/day in patients with a body weight over 80 kg); platelet count greater than 400,000/micro l and WBC less than 2500/micro l or Hb less than 10 g/dl at any dose of HU; presence of leg ulcers or other unacceptable muco-cutaneous manifestations at any dose of HU; HU-related fever.

Anagrelide treatment in 52 patients with chronic myeloproliferative diseases.

In this retrospective multi-centre study, we report our experience with anagrelide in the treatment of thrombocytosis in patients with chronic myeloproliferative diseases. Our study included 52 patients (age 20-78 years). The initial anagrelide dose was, in general, 0.5 mg once daily and mean maintenance dosage was 1.7 mg/day. The overall response rate was 79% including 75% complete remission and 4% partial remission. Forty-two patients (81%) had adverse effects and in 29% of the study population, the adverse effects necessitated cessation of anagrelide. The most common adverse effect was moderate anaemia (50%). Two patients experienced erectile dysfunction which has been described only once previously in association with anagrelide treatment. One patient progressed to acute leukaemia. However, this patient had been pre-treated with two potentially leukaemogenic drugs and had only been in short-term treatment with anagrelide. Furthermore, a total of 13 events were recorded. More than 25% of these events occurred in patients with platelet counts between 400 and 600 x 10(9)/l and almost 40% of all events occurred in patients with platelet counts above 400 x 10(9)/l. This observation supports the hypothesis that aggressive control of thrombocytosis to a platelet count <400 x 10(9)/l might reduce the number of thrombohaemorrhagic events. Anagrelide is safe and effective in reducing the platelet counts, but a high proportion of the patients discontinue treatment because of the adverse effects of the drug.

Thymic size in preterm neonates: a sonographic study.

AIM: To assess the variation in size of the thymus in vivo in preterm neonates and to identify relations between thymic size and gestational age (GA), birthweight, occurrence of postnatal infections and maternal alcohol and tobacco intake during pregnancy. METHODS: Eighty preterm neonates with a GA between 24 and 36 wk, and a birthweight between 490 and 4110 g were examined between days 0 and 19 after birth. The thymic size was assessed by sonography as a volume estimate, the so-called thymic index (Ti). The median Ti was 5.2 (1.2-17.9). Ti was positively correlated with birthweight and GA and negatively correlated with occurrence of postnatal infection (p < 0.01, p = 0.03, p = 0.05, R2 = 0.68). A correlation between thymic size and maternal alcohol and tobacco intake was not demonstrated. CONCLUSION: It is possible to assess the size of the thymus by sonography in very low-birthweight and preterm neonates. A normal range for Ti in preterm neonates has been established. The sonographic method is a safe and effective technique for measuring the size of the thymus in preterm infants.

SU6668 in idiopathic myelofibrosis--a rational therapeutic approach targeting several tyrosine kinases of importance for the myeloproliferation and the development of bone marrow fibrosis and angiogenesis.

Idiopathic myelofibrosis is a chronic myeloproliferative disorder being featured by progressive accumulation of connective tissue in concert with marked neovascularization (angiogenesis) of the bone marrow. Both fibrogenesis and angiogenesis are considered to develop consequent to the intramedullary release of various growth-promoting factors from rapidly proliferating and dysplastic megakaryocytes. Among these growth factors are platelet-derived growth factor (PDGF), basic fibroblast growth factor (bFGF), transforming growth factor beta (TGF-beta) and vascular endothelial growth factor (VEGF). The protein kinase inhibitor SU6668 is a potent antiangiogenic inhibitor of receptor tyrosine kinases, including those of VEGFR, PDGFR, bFGFR, and c-kit. The hypothesis is that SU6668 may be an effective agent in the treatment of idiopathic myelofibrosis. This compound has an inhibitory target profile on several tyrosine kinases involved in the myeloproliferation, the development of myeloid metaplasia (bFGFR, PDGFR, VEGFR, and c-kit) and the development of the major stromal changes in the bone marrow - fibrosis and angiogenesis (bFGFR, PDGFR, and VEGFR).