Calreticulin mutant mice develop essential thrombocythemia that is ameliorated by the JAK inhibitor ruxolitinib.

Mutations of calreticulin (CALR) are detected in 25-30% of patients with essential thrombocythemia (ET) or primary myelofibrosis and cause frameshifts that result in proteins with a novel C-terminal. We demonstrate that CALR mutations activated signal transducer and activator of transcription 5 (STAT5) in 293T cells in the presence of thrombopoietin receptor (MPL). Human megakaryocytic CMK11-5 cells and erythroleukemic F-36P-MPL cells with knocked-in CALR mutations showed increased growth and acquisition of cytokine-independent growth, respectively, accompanied by STAT5 phosphorylation. Transgenic mice expressing a human CALR mutation with a 52 bp deletion (CALRdel52-transgenic mice (TG)) developed ET, with an increase in platelet count, but not hemoglobin level or white blood cell count, in association with an increase in bone marrow (BM) mature megakaryocytes. CALRdel52 BM cells did not drive away wild-type (WT) BM cells in in vivo competitive serial transplantation assays, suggesting that the self-renewal capacity of CALRdel52 hematopoietic stem cells (HSCs) was comparable to that of WT HSCs. Therapy with the Janus kinase (JAK) inhibitor ruxolitinib ameliorated the thrombocytosis in TG mice and attenuated the increase in number of BM megakaryocytes and HSCs. Taken together, our study provides a model showing that the C-terminal of mutant CALR activated JAK-STAT signaling specifically downstream of MPL and may have a central role in CALR-induced myeloproliferative neoplasms.

TET2 is essential for survival and hematopoietic stem cell homeostasis.

Ten-Eleven-Translocation 2 (TET2) is an enzyme that catalyzes the conversion of 5-methylcytosine into 5-hydroxymethylcytosine (5-hmC) and thereby alters the epigenetic state of DNA; somatic loss-of-function mutations of TET2 are frequently observed in patients with diverse myeloid malignancies. To study the function of TET2 in vivo, we analyzed Ayu17-449 (TET2(trap)) mice, in which a gene trap insertion in intron 2 of TET2 reduces TET2 mRNA levels to about 20% of that found in wild-type (WT) mice. TET2(trap/trap) mice were born at Mendelian frequency but died at a high rate by postnatal day 3, indicating the essential role of TET2 for survival. Loss of TET2 results in an increase in the number of hematopoietic stem cells (HSCs)/progenitors in the fetal liver, and TET2(trap/trap) HSCs exhibit an increased self-renewal ability in vivo. In competitive transplantation assays, TET2(trap/trap) HSCs possess a competitive growth advantage over WT HSCs. These data indicate that TET2 has a critical role in survival and HSC homeostasis.

Clinical significance of CADM1/TSLC1/IgSF4 expression in adult T-cell leukemia/lymphoma.

Cell adhesion molecule 1 (CADM1/TSLC1) was recently identified as a novel cell surface marker for adult T-cell leukemia/lymphoma (ATLL). In this study, we developed various antibodies as diagnostic tools to identify CADM1-positive ATLL leukemia cells. In flow cytometric analysis, the percentages of CD4(+)CADM1(+) double-positive cells correlated well with both the percentages of CD4(+)CD25(+) cells and with abnormal lymphocytes in the peripheral blood of patients with various types of ATLL. Moreover, the degree of CD4(+)CADM1(+) cells over 1% significantly correlated with the copy number of the human T-lymphotropic virus type 1 (HTLV-1) provirus in the peripheral blood of HTLV-1 carriers and ATLL patients. We also identified a soluble form of CADM1 in the peripheral blood of ATLL patients, and the expression levels of this form were correlated with the levels of soluble interleukin 2 receptor alpha. Moreover, lymphomas derived from ATLL were strongly and specifically stained with a CADM1 antibody. Thus, detection of CD4(+)CADM1(+) cells in the peripheral blood, measurement of serum levels of soluble CADM1 and immunohistochemical detection of CADM1 in lymphomas would be a useful set of markers for disease progression in ATLL and may aid in both the early diagnosis and measurement of treatment efficacy for ATLL.

Non-D Rh antibodies appearing after apheresis platelet transfusion: stimulation by red cells or microparticles?

BACKGROUND: Apheresis platelets (APs) have gained favour over whole blood-derived platelets on the presumption that they are less likely to provoke alloimmunization to red-blood-cell antigens. CASE REPORTS: Non-D Rh antibodies appeared in three patients after apheresis platelet transfusion. Anti-C and anti-E arose in two female patients with previous antigen exposure. Both anti-c and anti-E arose in a male recipient with no prior transfusion history. MATERIALS AND METHODS: Fifty APs were analysed for residual RBCs and RBC-derived microparticles, using samples obtained from a local blood centre. Cells and microparticles were quantified with a flow cytometry gating scheme, using PE-labelled anti-CD235a (glycophorin A) and FITC-labelled anti-CD41a (platelet gp IIb/IIIa) to distinguish lineage. RESULTS: Apheresis platelets were found to contain a mean of 7·5×10(6) (95% C.I. [6·3-8·5×10(6) ]) RBCs on one manufacturer's device and 5·2×10(6) (95% C.I. [4·0-6·3×10(6) ]) RBCs on another's. RBC-derived microparticles averaged 210·7×10(6) (95% C.I. [166·2-254·2×10(6) ]) on one manufacturer's device and 232·3×10(6) (95% C.I. [194·3-272·9×10(6) ]) on another's. These counts all correspond to volumes of <1 µl. CONCLUSION: Despite RBC contamination of APs below commonly accepted thresholds for Rh immunogenicity, AP transfusion can provoke non-D Rh antibody formation. RBC-derived microparticles, smaller but more numerous than RBCs, are volumetrically comparable and may be a hitherto underappreciated antibody stimulus. Further microparticle research will guide considerations of extended phenotypic matching of platelet components.

Absence of gain-of-function JAK1 and JAK3 mutations in adult T cell leukemia/lymphoma.

Janus kinase 1 (JAK1) and JAK3 plays a critical role in lymphocyte proliferation and differentiation. Somatic JAK1 mutations are found in 18% of adult precursor T acute lymphoblastic leukemias and somatic JAK3 mutations are found in 3.3% of cutaneous T cell lymphomas. Some of the mutations are confirmed as a gain-of-function mutation and are assumed to be involved in leukemogenesis. Adult T cell leukemia/lymphoma (ATLL) is a type of T cell neoplasm, and activation of JAK/STAT pathways is sometimes observed in them. We investigated JAK1 and JAK3 mutations in 20 ATLL patients. No JAK1 mutations were found, and five types of single nucleotide polymorphisms were observed in 12 cases, whose frequencies almost match those in Asian populations. As for JAK3, a synonymous mutation was found in one case. JAK1 and JAK3 mutations are unlikely involved in the leukemogenesis of ATLL.

Development of ET, primary myelofibrosis and PV in mice expressing JAK2 V617F.

An acquired JAK2 V617F mutation is found in most patients with polycythemia vera (PV), and about half of patients with essential thrombocythemia (ET) or primary myelofibrosis (PMF). Mice transplanted with bone marrow cells in which JAK2 V617F was retrovirally expressed developed PV-like features, but not ET or PMF. To address the contribution of this mutation to the pathogenesis of these three MPDs, we generated two lines of JAK2 V617F transgenic mice. One line showed granulocytosis after 4 months of age. Among 43 mice, 8 (19%) showed polycythemia and 15 (35%) showed thrombocythemia. The second line showed extreme leukocytosis and thromobocytosis. They showed anemia that means Hb value from 9 to 10 g per 100 ml when 1 month old. Myeloid cells and megakaryocytes were predominant in the bone marrow of these animals, and splenomegaly was observed. The expression of JAK2 V617F mRNA in bone marrow cells was 0.45 and 1.35 that of endogenous wild-type JAK2 in the two lines, respectively. In vitro analysis of bone marrow cells from both lines showed constitutive activation of ERK1/2, STAT5 and AKT, and augmentation of their phosphorylations by cytokine stimulation. We conclude that in vivo expression of JAK2 V617F results in ET-, PMF- and PV-like disease.

[Primary splenic CD8-positive diffuse large B-cell lymphoma].

A 71-year-old woman was admitted for further examination of an increased serum LDH level. Abdominal ultrasonography and CT scan showed a large tumor in her spleen. Because malignant lymphoma was suspected, the spleen was removed for diagnosis and treatment planning. The histopathological and immunohistochemical features of the tumor indicated diffuse large B-cell lymphoma (DLBL). The flow-cytometric immunophenotype of the lymphoma cells was CD2-, CD3-, CD4-, CD5-, CD8+, CD10+, CD19+, CD20+, CD23-, kappa+, lambda-, CD25+, and CD56-. From these findings, the patient was diagnosed as having CD8+ DLBL. To our knowledge, this is the first reported case of primary splenic CD8-positive DLBL.

[Copper deficiency anemia and neutropenia secondary to total gastrectomy].

We report a case of copper deficiency with anemia and neutropenia due to dumping syndrome after total gastrectomy. Parenteral nutrition containing cupric sulfate promptly improved the dumping syndrome, anemia and neutropenia. This case suggests that total gastrectomy with dumping syndrome can cause copper deficiency, and that copper deficiency should be considered when encountering similar patients with severe anemia and neutropenia.

A case of acute hepatitis A with marked hemophagocytosis in bone marrow.

A previously well 18-year-old female was referred to our hospital because of abnormalities of blood biochemistry and slight jaundice. Because serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels were elevated more than 6000 IU/L, the patient was suspected to have acute viral hepatitis. The platelet count on admission was 9.7x10(4)/µl, which was decreased from the initial value of 21x10(4)/µl for 3 days. The coagulation tests revealed marked elevation of D-dimmer, fibrinogen degradation products and thrombin-antithrombin III complex suggesting increase in fibrinolysis. Serum levels of high density lipoprotein cholesterol and ferritin were markedly decreased and increased, respectively. The bone marrow smears revealed proliferation of mature histiocytes ingesting platelets and erythrocytes, these pathological findings were consistent with those of hemophagocytic syndrome (HPS). In addition, anti-hepatitis A IgM antibody in the serum and hepatitis A virus (HAV) RNA in the stool were positive. Therefore, the patient was diagnosed as having acute hepatitis A with probable HPS. Since a fulminant clinical course was suspected, glucocorticoid pulse therapy was started immediately 7 days after onset and a favorable clinical outcome resulted.

Hepatocyte growth factor/scatter factor enhances the thrombopoietin mRNA expression in rat hepatocytes and cirrhotic rat livers.

BACKGROUND: Although thrombopoietin (TPO) is mainly produced in the liver, the regulatory mechanism of TPO gene expression in hepatocytes remains unclear. The role of TPO in thrombocytopenia associated with liver cirrhosis has not been identified. METHODS: We examined the effects of various growth factors and cytokines on TPO mRNA expression in adult rat hepatocytes in primary cultures using a semiquantitative reverse transcription-polymerase chain reaction assay. RESULTS: Among them, only hepatocyte growth factor/scatter factor (HGF/SF) enhanced TPO mRNA expression; other growth factors (epidermal growth factor and transforming growth factor-beta) and cytokines (erythropoietin, granulocyte-colony stimulating factor, granulocyte-macrophage-colony stimulating factor, interleukin (IL)-3, IL-6 and interferon-gamma) did not. Next, we examined TPO mRNA expression in the livers of rats with CCl4-induced cirrhosis, the effects of HGF/SF on hepatic TPO mRNA expression and peripheral platelet and bone marrow megakaryocyte counts in the cirrhotic rats. In the cirrhotic rats, both the peripheral platelet count and TPO mRNA expression in the livers were markedly decreased compared with those of the normal rats. The administration of HGF/SF to the cirrhotic rats stimulated TPO mRNA expression in the livers and resulted in significant increases of peripheral platelets and bone marrow megakaryocytes. CONCLUSIONS: These results suggest that HGF/SF is a possible regulatory factor for TPO gene expression and that HGF/SF increases platelet production through an enhancement of TPO mRNA expression in the livers of cirrhotic rats.

Clinical significance of CD45RO expression on peripheral blood mononuclear cells in HTLV-I-infected individuals.

The phenotype of peripheral blood mononuclear cells (PBMC) was examined in 13 healthy volunteers, 26 HTLV-I carriers, and 58 ATL patients (22 smouldering, five chronic, 24 acute, and seven lymphoma type). The percentage of CD4+, CD25+, CD28+ and CD45RO+ cells in the PBMC of the chronic and acute type patients was significantly higher than that of the volunteers, whereas the percentage of CD8+ and CD45RA+ cells in these patients was significantly low. The histogram for CD45RO fluorescence intensity (FI) revealed two patterns: pattern A consisted of CD45RO+ cells with high FI (CD45ROhigh) and intermediate FI (CD45ROint). Pattern B consisted exclusively of CD45ROhigh. Pattern A was evident in all volunteers. The percentage of subjects showing pattern B was increased in an order that reflected disease progression. In the patients with pattern A, the CD45ROint cells were CD4+ and CD8-, and the FI of CD2, CD3, and Fas within the CD45ROint cells appeared to be lower than that within the CD45ROhigh cells. The acute type patients with pattern A had a significantly longer survival curve than that of these patients with pattern B. These results suggest that the presence of CD45ROint cells may be related to protection against disease progression in HTLV-I-infected individuals.

[Study on prognostic factors in twenty-five patients with myelodysplastic syndrome].

Twenty-five consecutive patients with myelodysplastic syndrome (MDS) were followed in the Second Department of Internal Medicine, Miyazaki Medical School from 1984 to 1993. The diagnosis of MDS was morphologically based on the criteria of FAB. At the time of diagnosis, 9 patients had refractory anemia (RA), 1 had RA with ring sideroblasts (RARS), 6 had RA with excess blasts (RAEB), 6 had RAEB in transformation (RAEB-t), and 3 had chronic myelomonocytic leukemia (CMMoL). Prognostic factors involved in survival times and progression to leukemia were analyzed in these patients; FAB classification of MDS, age, sex, peripheral blood cell counts, bone marrow examination, karyotype, numbers of blasts. None of these prognostic factors had a significant effect on the prognosis of MDS patients. Study of the therapeutic effects on MDS patients revealed no significant increase of survival time in treated MDS patients compared to non-treated patients. Further, no significant difference in survival time was found between MDS patients treated with or without anticancer drugs. These results indicated that MDS patients were pathologically and therapeutically heterogeneous.

Observation of T cell surface antigens in the clinical course of adult T-cell leukemia: case report of a spontaneous remission.

A patient with acute adult T-cell leukemia (ATL) in whom spontaneous remission was observed without any specific treatment having been given is described. The abnormal cell phenotype was CD4+, CD45RO+ and CD8-. As the number of abnormal cells decreased, CD4+ cell count decreased and CD8+ cells and CD45RA+ cells increased to normal levels (45 and 77%, respectively). Further, the number of cells with CD45RO antigen of intermediate fluorescence intensity increased. Five months after admission, we assessed the patient as being in a state of complete clinical remission; no abnormal cells were detected in peripheral blood, lymph node enlargement had disappeared and the serum chemistry was normal. When the abnormal cells in peripheral blood had disappeared, Southern blot analysis for HTLV-I proviral DNA still revealed a weak monoclonal band with EcoRI digestion, and HTLV-I proviral DNA was detected by polymerase chain reaction analysis. Thus, it appeared that very few abnormal cells persisted although the laboratory findings for ATL were normal. Our case could contribute to the understanding of the mechanism that underlies spontaneous remission in ATL.

[Successful chronic daily administration of oral etoposide for a case of adult T cell leukemia].

A 54-year-old woman with leucocytosis and skin lesion was hospitalized and diagnosed as chronic type adult T cell leukemia (ATL) in August 1989. Since her ATL cell count and LDH level increased after hospitalization, oral administration of etoposide was started at a dose of 100 mg/day for seven days. The oral administration of etoposide induced another chronic state of ATL. After 10 months without medication, she was readmitted because of an acute ATL crisis. After daily administration of etoposide at a dose of 50 mg/day, the white blood cell count and serum LDH level decreased to the normal range, and abnormal lymphocytes of peripheral blood disappeared. The low-dose daily administration of etoposide at a dose of 25 approximately 50 mg/day could be maintained over six months. No severe side effects except for alopecia and mild myelosuppression were noted during the treatment. Chronic daily administration of oral etoposide is one candidate for the treatment of ATL in an outpatient clinic.

A new family with Joseph disease in Japan. Homovanillic acid, magnetic resonance, and sleep apnea studies.

Four male patients and one female patient of a new family with Joseph disease are reported. Their disease was characterized by autosomal dominant inheritance, bulging eyes, rigidity and spasticity of the lower extremities, dystonia, and bradykinesia. Cerebrospinal fluid homovanillic acid level was markedly reduced. Levodopa improved dystonia. Magnetic resonance imaging revealed mild atrophy of the frontal lobe and the cerebellum and marked atrophy of the lenticular nucleus and the brain stem. Polysomnographic studies revealed non-rapid eye movement stage central type sleep apnea syndrome. This is the first report using magnetic resonance imaging and sleep apnea studies of Joseph disease.