High numbers of programmed cell death-1-positive tumor infiltrating lymphocytes correlate with early onset of post-transplant lymphoproliferative disorder

Post-transplant lymphoproliferative disorder (PTLD) is a life-threatening complication of transplantation. In addition to reactivation of Epstein-Barr virus in immunocompromised patients, impaired tumor immunity is suggested to be a risk factor for PTLD. However, it remains unclear whether immune suppressive tumor-infiltrating lymphocytes (TILs) correlate with the occurrence or prognosis of PTLD. We analyzed TILs in 26 patients with PTLD to elucidate the clinicopathological significance of the expression of PD-1 and FoxP3, which are associated with exhausted T-cells and regulatory T-cells (Tregs), respectively. Numbers of PD-1⁺ TILs in the PTLD specimens were significantly higher in patients who developed PTLD early after transplantation (P = 0.0040), while numbers of FoxP3⁺ TILs were not (P = 0.184). There was no difference in overall response rate regardless of the expression of PD-1 or FoxP3. FoxP3^high patients tended to have a shorter time to progression compared with FoxP3^low patients, especially in the case of FoxP3^high patients with diffuse large B-cell lymphoma-subtype PTLD (P = 0.011), while PD-1^high patients did not. These results suggest that T-cell exhaustion may be mainly associated with PTLD development, while immune suppression by Tregs may be dominant in enhanced progression of PTLD following disease occurrence.

A New Approach for Determining Short-Term, Objective Prognostic Predictive Methods for Terminal Cancer Patients Based on the Change Point of Laboratory Test Values

BACKGROUND

In terminal phase cancer, predicting a prognosis precisely plays an important role for patients and their families to live meaningful lives. However, there are no established short-term, objective prognostic predictive methods.

OBJECTIVE

To develop simple, short-term, objective prognostic predictive methods through detecting a change point for laboratory test values.

DESIGN

A retrospective chart review.

SETTING/SUBJECTS

Subjects were cancer patients aged ≥16 years and discharged dead from Osaka University Hospital in 2008.

MEASUREMENTS

Using different laboratory test values, new prognostic predictive methods were determined based on either six laboratory test values (white blood cell [WBC], platelet [PLT], C-reactive protein, blood urea nitrogen [BUN], aspartate aminotransferase [AST], and lactase dehydrogenase [LDH]): the WPCBAL score, or five test values (WBC, PLT, BUN, AST, and LDH): the WPBAL score. Their utility, including sensitivity and specificity, was compared with that of Glasgow prognostic scores (GPSs).

RESULTS

In total, 121 cancer patients were enrolled. WPCBAL and WPBAL scores showed higher sensitivity (0.88 and 0.91 vs. 0.68), specificity (0.79 and 0.70 vs. 0.53), negative predictive value (0.98 and 0.97 vs. 0.76), and a much larger relative risk (16.5 and 14.2 vs. 1.78) as prognostic predictors within two weeks of death than GPS as a prognostic predictor within three weeks of death.

CONCLUSION

This is the first study that suggests that the objective prognostic predictive methods, through detecting the change point of laboratory test values, are useful for predicting short-term prognosis. The WPCBAL score and WPBAL score could objectively predict the remaining lifetime within two weeks of mortality.

Tentative diagnostic criteria and disease severity classification for Castleman disease: A report of the research group on Castleman disease in Japan

OBJECTIVES

To determine the tentative diagnostic criteria and disease severity classification for Castleman disease (CD) and describe the clinical and pathologic features among human herpesvirus 8 (HHV-8) negative idiopathic multicentric CD (iMCD) in the Japanese population.

METHODS

We established the working groups for the research of CD in Japan and had meetings to discuss and define the tentative diagnostic criteria and disease severity classification for CD. We subsequently analyzed 142 patients classified into iMCD by using the nationwide Japanese patient registry.

RESULTS

We proposed the preliminary diagnostic criteria and disease severity classification for CD based on our discussion. In addition, we made a proposal for the disease activity score. We identified clinical and pathological features of patients with iMCD diagnosed by these diagnostic criteria. In the disease severity classification, 37, 33 and 30% patients were categorized into mild, moderate and severe diseases, respectively.

CONCLUSION

This is the first proposal for diagnosis and classification of CD by the Japanese group. Further studies are required to validate whether they can distinguish CD from other inflammatory diseases and to determine their sensitivity and specificity.

Quantitative polymerase chain reaction analysis with allele-specific oligonucleotide primers for individual IgH VDJ regions to evaluate tumor burden in myeloma patients

Quantitative polymerase chain reaction (PCR) with patient-specific, allele-specific oligonucleotide (ASO) primers for individual immunoglobulin H VDJ region (ASO-PCR) amplification was performed using several sources of clinical material, including mRNA from peripheral blood cells (PBMNCs), whole bone marrow cells (BMMNCs), and the CD20+ CD38- B-cell population in bone marrow, as well as cell-free DNA from the sera of patients with multiple myeloma (MM). We designed the ASO primers and produced sufficient PCR fragments to evaluate tumor burden in 20 of 30 bone marrow samples at diagnosis. Polymerase chain reaction amplification efficiency depended on primer sequences because the production of ASO-PCR fragments did not correlate with serum M-protein levels. However, the ASO-PCR levels in BMMNCs showed statistically significant correlations with those in PBMNCs and CD20+ CD38- B-cells. The good association between the BMMNC and PBMNC data indicated that PBMNCs could be a suitable source for monitoring minimal residual disease (MRD). In the case of cell-free DNA, ASO-PCR levels showed a unique pattern and remained high even after treatment. Because the sequence information for each ASO-PCR product was identical to the original, the cell-free DNA might also be useful for evaluating MRD. Moreover, the ASO-PCR products were clearly detected in 17 of 22 mRNA samples from CD20+ CD38- populations, suggesting that MM clones might exist in relatively earlier stages of B cells than in plasma cells. Thus, ASO-PCR analysis using various clinical materials is useful for detecting MRD in MM patients as well as for clarifying MM pathogenesis.

Footwear Exchange Has No Influence on the Incidence of Febrile Neutropenia in Patients Undergoing Chemotherapy for Hematologic Malignancies

Objective:

To determine whether footwear exchange affects the incidence of febrile neutropenia among patients undergoing chemotherapy for hematologic malignancies.

Design:

Open trial with historical comparison.

Setting:

The 12-bed high-efficiency particulate air-fil-tered hematology unit at Osaka University Hospital, Suita, Japan.

Patients:

Those with hematologic malignancies who underwent chemotherapy from January 1997 through January 2003. Footwear exchange was discontinued in January 2000.

Methods:

The surveillance system was based on the National Nosocomial Infections Surveillance System of the Centers for Disease Control and Prevention. Rates of febrile neutropenia were calculated for neutropenic patient-days (ie, days with neutropenia < 500/μL).

Results:

From January 1997 through December 1999 and from February 2000 through January 2003, 58 and 54 patients endured 237 and 184 neutropenic periods following chemotherapy, and their total neutropenic days were 3,123 and 2,503, respectively. They showed episodes of febrile neutropenia 89 and 68 times, respectively. Infection rates were 28.5 and 27.2 per 1,000 neutropenic patient-days (P = .83), respectively.

Conclusion:

The incidence of febrile neutropenia was not affected by footwear exchange. In hematology units, changing shoes does not appear to affect the rate of infections during neutropenic periods.

[The development history and future perspective of molecularly targeted therapy]

The origin of molecularly targeted drugs dates back to 'magic bullet' theory proposed by Paul Ehrlich. The success of Abl tyrosine kinase inhibitor, imatinib for the treatment of chronic myeloid leukemia realized that small molecules inhibiting ATP binding can become specific inhibitors for the relevant kinases. Subsequently, a number of kinase inhibitors which targets various signal transduction molecules, are in the clinical field or under development. The clinical success of antibody therapeutics has been achieved by the genetic engineering which makes human-mouse chimeric, humanized or human antibody. To augment the therapeutic effects of antibody, radioisotope-conjugate antibody and antibody-drug conjugate have come to the clinical field. In the near future, we have to develop the combination therapy of molecularly targeted drugs and also inhibitors for epigenetic and transcriptional regulators.

[Effect of the administration of zoledronic acid on life expectancy in patients with multiple myeloma with or without renal impairment]

Zoledronic acid(ZA)is believed to exert anticancer effects in patients with multiple myeloma(MM). For patients with impaired renal function, its dosage should be determined according to creatinine clearance(Ccr). However, there is no reported difference in life expectancy improvement between those with and without renal impairment. Therefore, we conducted a retrospective study to investigate this clinical question. Seventy-eight MM patients receiving ZA injections were selected and divided into 2 groups: (1)normal group(n=39), baseline Ccr≥60mL/min, and(2)impaired group(n=39), baseline Ccr<60mL/min. Patients in the normal group received a significantly higher initial dose(p<0.001), were of a younger age(p<0.001), had lower b2-microglobulin(b2-M)levels(p<0.001), and had higher rates of prior hematopoietic stem cell transplantation(p<0.001)than those in the impaired group. We then compared the survival rate between 31 patients in the normal group and 27 patients in the impaired group whose treatment outcome data were available and found no significant difference(p=0.251). Therefore, our results suggest that the survival rate on ZA administration may not differ between MM patients with and without renal impairment.

Managing hepatitis B virus carriers with systemic chemotherapy or biologic therapy in the outpatient clinic

AIM

  The number of outpatients receiving systemic chemotherapy in Japan has recently increased. We retrospectively examined whether hepatitis B virus (HBV) carriers were safely treated and managed with systemic chemotherapy or biologic agents as outpatients at our oncology center.

METHODS

  A total of 40 115 consecutive infusion chemotherapy or biologic therapies were administrated to 2754 outpatients in the Chemotherapy and Oncology Center at Osaka University Hospital from December 2003 to March 2011. We first studied the prevalence of outpatients with hepatitis B surface antigen (HBsAg), and then retrospectively evaluated a database to determine the frequencies of testing for other HBV-related markers and the incidence of developing hepatitis or HBV reactivation in patients positive for HBsAg. As a control for comparison, we also examined these same factors in patients with hepatitis C virus antibody (anti-HCV).

RESULTS

  The majority of physicians at our hospital screened for HBsAg (95%) and anti-HCV (94%) prior to administrating chemotherapy. Of the 2754 outpatients, 46 (1.7%) were positive for HBsAg and 90 (3.3%) were positive for anti-HCV. Fifteen patients that were HBsAg positive were treated with lamivudine or entecavir prior to chemotherapy. None of the patients with HBsAg taking a prophylactic antiviral developed hepatitis, and only one breast cancer patient without prophylactic antiviral treatment (1/31 [3.2%]) developed hepatitis due to HBV reactivation.

CONCLUSION

  HBV reactivation occurred in outpatients without prophylactic antiviral treatment, but the incidence was relatively low.

[A case of chronic active Epstein-Barr virus infection associated with recurrent cerebellar ataxia and skin eruptions]

A 62-year-old woman presented with subacute cerebellar ataxia, lymph node swelling and skin eruption. Laboratory tests revealed elevated titers of anti-VCA-IgG antibody and anti-EADR-IgG antibody, with Epstein-Barr virus (EBV) DNA detected from the blood and CSF by PCR. Since these data were highlighted with the diagnosis of chronic active EBV infection (CAEBV) and her ataxia improved concomitantly with the remission of other infectious mononucleosis-like symptoms, we supposed her ataxia is associated with CAEBV. Five years later, at the age of 67, her ataxia relapsed concurrently with skin eruptions, whereas MRI demonstrated progression of cerebellar atrophy. After high-dose intravenous methylprednisolone treatment, the clinical symptoms resolved. Initial infection of EBV in childhood often causes autoimmune acute cerebellitis but cerebellar ataxia has rarely been described in CAEBV. Furthermore, immunohistochemical analysis revealed a reactivity of the patient's serum and CSF on rat cerebellum, suggesting an autoimmune pathomechanism for the ataxia.

Constitutively active FGFR3 with Lys650Glu mutation enhances bortezomib sensitivity in plasma cell malignancy

The ectopically expressed fibroblast growth factor receptor 3 (FGFR3) and its constitutively active mutations have been detected in patients with multiple myeloma (MM). This study investigated whether the cytotoxic effects of bortezomib on malignant plasma cells are associated with FGFR3 expression and the existence of mutations of FGFR3.

MATERIALS AND METHODS

Cell apoptosis assays were performed in a plasmacytoma cell line, FR4 cells and a myeloma cell line, RPMI8226 cells overexpressing wild-type FGFR3 (FGFR3(WT)) or two different mutants, FGFR3(K650E) or FGFR3(Y373C), and the induction of endoplasmic reticulum (ER) stress protein was compared between each type of cell.

RESULTS

FR4 cells with FGFR3(K650E) showed enhanced sensitivity to bortezomib together with increased induction of ER stress proteins, compared to FR4 cells with mock, FGFR3(WT) or FGFR3(Y373C). RPMI8226 cells with FGFR3(K650E) also showed enhanced bortezomib sensitivity.

CONCLUSION

This study indicated that FGFR3K650E is associated with bortezomib sensitivity in malignant plasma cells via ER stress pathways.

Intravascular lymphomatosis initially suspected from uterine cytology: a case report

BACKGROUND

Because recognizable lesions are often absent, selection of biopsy sites for diagnosis of intravascular large B-cell lymphoma (IVL) is frequently problematic.

CASE

A 59-year-old woman was admitted with fever and general fatigue. Combined physical and roentgenographic examinations revealed neither lymphadenopathy, hepatosplenomegaly nor mass lesions in other organs. Serum lactate dehydrogenase level was 1412 IU/L. There were no genital symptoms, but uterine cytologic examination revealed large cells distributed in a noncohesive pattern. These cells had a large, irregularly shaped nucleus in which several nucleoli were discernible and showed positive immunoreactivity for leukocyte common antigen. Three months after admission, neurologic symptoms appeared, and magnetic resonance imaging revealed multiple nodular lesions in the brain. Biopsy specimens from the brain lesion showed the proliferation of large lymphoid cells filling the lumina of small vessels and Virchow-Robin's space. Immunohistochemistry revealed that the tumor cells were positive for CD20 and CD79a but negative for CD3, indicative of IVL.

CONCLUSION

Uterine cytologic and/or histologic examinations could be the choice for diagnosis of IVL, even when genital symptoms are absent.

AML1/RUNX1 works as a negative regulator of c-Mpl in hematopoietic stem cells

In this study, we analyzed the roles for AML1/RUNX1 in the regulation of the c-mpl promoter. Wild-type AML1 activated the c-mpl promoter through the proximal AML-binding site in luciferase assays using 293T and HeLa cells. In accord with this result, electrophoretic mobility shift assay and chromatin immunoprecipitation assays demonstrated that AML1 bound to this site. Next, we analyzed the function of AML1 using a mutant of AML1 lacking the C terminus (AML1dC), which was originally found in a patient with myelodysplastic syndromes. AML1dC dominant-negatively suppressed transcriptional activity of wild-type AML1. However, unexpectedly, AML1dC-transduced murine c-Kit(+)Sca1(+)Lineage(-) cells expressed c-mpl mRNA and c-Mpl protein more abundantly than mock-transduced cells, which led to the enhanced thrombopoietin-mediated proliferation. Moreover, when AML1dC was induced to express during the development of hematopoietic cells from embryonic stem (ES) cells, AML1dC augmented the c-Mpl expression on hematopoietic stem/progenitor cells. Furthermore, we found that early hematopoietic cells that derived from AML1(+/-) ES cells expressed c-Mpl more intensely than those that developed from wild-type ES cells. In contrast, AML1dC hardly affected c-Mpl expression and maturation of megakaryocytes. As for the mechanism of the different roles of AML1 in the regulation of the c-mpl promoter, we found that AML1 forms a complex with a transcription repressor mSin3A on the c-mpl promoter in hematopoietic stem/progenitor cells, although it forms a complex with a transcription activator p300 on the same promoter in megakaryocytic cells. Together, these data indicate that AML1 can regulate the c-mpl promoter both positively and negatively by changing the binding partner according to cell types.

[Trial of "Huber Plus" in outpatients with chemotherapy by blood port system]

We evaluated the advantages and disadvantages of Huber Plus through three outpatients treated with central venous (CV) port chemotherapy (FOLFOX). One of the three outpatients first received chemotherapy with safety huber (Huber Plus) in this study, and the huber needle was changed from non-safety to a safety huber (Huber Plus) in two of the three outpatients. All three outpatients were taught about needle removal methods and port care. In patients? education, 1) we used a skin model and training CV port, and 2) dressing materials were used as film dressing plus three-point fixation by Fixomull stretch. As a result, the safety system assured zero incidents. Moreover, the evaluation revealed that operability and pain of Huber Plus were not clinical problems. We suggest that Huber Plus is applicable in outpatient chemotherapy and that our care plan with patients? education might become a standard treatment.

[Our experience using "Huber Plus" needles in our infusion center]

We conducted a pilot trial to compare the operability and safety of two huber needles in the infusion center. In the present study, we used huber needles without the safety cover and one huber needle with the safety cover (Huber Plus(R)). Both huber needles were used nine times. The successful puncture rate of the first time puncture and the incidence of needle accidents with both huber needles were 100% and 0%, respectively. The evaluation of pain and uneasiness by VAS (Visual Analogue scale)revealed the superiority of the safety needle over the than non-safety needle(pain: 3.8 vs 2.6, uneasiness: 3.7 vs 0.5). To our knowledge, this is the first report of the safety of the huber needle in Japan. This system may be recommended in Japan to avoid needle stick injuries, patient pain and uneasiness.

[Incident surveillance in outpatients treated with hepatic arterial infusion (HAI) chemotherapy with infusion pump]

PURPOSE

An incident situation of hepatic arterial infusion (HAI) chemotherapy was investigated, and the improvement methods were evaluated.

METHODS

As a result of surveillance, all incidents were observed in patients during five day continuous HAI infusion conditions: 1) Reverse-flow hemorrhage occurred at home by disconnection of the catheter; and 2) hemorrhage by natural withdrawal of the huber needle, were diagnosed. For 1) we further taped the catheter connection area by Tegaderm and changed the dressing material from SILKYPORE DRESSING (10 x 13 cm and 4 x 6.5 cm in absorption part) plus two-person fixation by Fixomull stretch to IV3000 (9 x 12 cm non-absorption part) plus three-person fixation by Fixomull stretch. Moreover, we changed the needle type (subcutaneous adiposus thickness) from 22 G x 3/4 inch to 20 G x 1 inch.

RESULTS AND CONCLUSIONS

The incidents were not observed in 72 patients treated with HAI after improvement. We suggest that prevention of hemorrhage by further taping the catheter connection and improved stability of the needle by dressing proved effective. In conclusion, HAI incident surveillance may well be an important way to care for outpatients treated with HAI chemotherapy, and we thus intend to continue the HAI incident surveillance to improve the nursing care.

[Present situation and problems of the ordering system type infusion center]

We examined four problems of the ordering system type infusion center. In this system,regimen is made by chief physician and cared by the staff in the infusion center. 1) In securing of the staff, an upbringing of doctors and IV nurses are important. 2) An evidence-based regimen is necessary in order to minimize the differences of regimen made by each doctor. 3) A facility expansion might reduce an incident risk. 4) As the condition of patient suddenly changes,the chief physician of the patient should be contacted. We suggest that it is particularly important to make these problems clarified and solved by the team within the institution.

Unicentric and multicentric Castleman's disease

Castleman's disease (CD) appears at ubiquitous lymph nodes. To date, detection of the lesion focus for CD has mainly been carried out by physical examination and radiological findings, such as X-ray analysis, CT and MRI. 18F-FDG PET visualizes the active focus of glucose metabolism and the clinical value has been investigated for many different tumours. Previous studies of 18F-FDG PET for CD have only reported four cases of unicentric CD and no cases of multicentric CD. In this paper, we report two cases of CD, one with unicentric CD and one with multicentric CD. We demonstrate that the use of 18F-FDG PET for the detection and monitoring of patients with CD, especially multicentric CD, would be effective.

The Scaffolding Adapter Gab2, via Shp-2, Regulates Kit-evoked Mast Cell Proliferation by Activating the Rac/JNK Pathway

The scaffolding adapter Gab2 mediates cell signaling and responses evoked by various extracellular stimuli including several growth factors. Kit, the receptor for stem cell factor (SCF), plays a critical role in the proliferation and differentiation of a variety of cell types, including mast cells. Kit, via Tyr(567) and Tyr(719), activates Src family kinases (SFK) and PI3K respectively, which converge on the activation of a Rac/JNK pathway required for mast cell proliferation. However, how Kit Tyr(567) signals to Rac/JNK is not well understood. By analyzing Gab2(-/-) mast cells, we find that Gab2 is required for SCF-evoked proliferation, activation of Rac/JNK, and Ras. Upon Kit activation in wild-type mast cells, Gab2 becomes tyrosyl-phosphorylated and associates with Kit and Shp-2. Tyr(567), an SFK binding site in Kit, and SFK activity were required for Gab2 tyrosyl phosphorylation and association with Shp-2. By re-expressing Gab2 or a Gab2 mutant that cannot bind Shp-2 in Gab2(-/-) mast cells or acutely by deleting Shp-2 in mast cells, we found that Gab2 requires Shp-2 for SCF-evoked Rac/JNK, Ras activation, and mast cell proliferation. Lastly, by analyzing mast cells from mice with compound Gab2 and Kit Y719F mutations (i.e., Gab2(-/-): KitY719F/Y719F mice), we find that Gab2, acting in a parallel pathway to PI3K from Kit Tyr(719), regulates mast cell proliferation and development in specific tissues. Our data show that Gab2 via Shp-2 is critical for transmitting signals from Kit Tyr(567) to activate the Rac/JNK pathway controlling mast cell proliferation, which likely contributes to mast cell development in specific tissues.

Endolymphatic hydrops as a cause of audio-vestibular manifestations in relapsing polychondritis

Relapsing polychondritis (RP) is characterized by inflammation and subsequent degeneration of cartilage. We report a 61-year-old woman who had RP with audio-vestibular manifestations. She was also diagnosed as having a myelofibrosis with myeloid metaplasia (MMM). Bilateral endolymphatic hydrops (EH) was confirmed by dominant -SP/AP of the electrocochleogram (ECochG). When thalidomide and prednisolone were prescribed for the treatment of MMM, symptoms of RP -- including the inner ear dysfunction -- were ameliorated. Isosorbide, one of the osmotic diuretics commonly used for the treatment of Meniere's disease (MD) in Japan, was also effective in keeping her free from inner ear dysfunction. This is the first report to confirm the existence of EH in a patient with RP with audio-vestibular manifestations. We suppose that an immunological imbalance due to MMM, in conjunction with a specific immunogenetic background, may have played a role in the pathogenesis of RP and the formation of EH in this patient.

Roles of tyrosine residues 845, 892 and 922 in constitutive activation of murine FLT3 kinase domain mutant

FLT3 tyrosine kinase domain (TKD) mutations are detected in approximately 7% of acute myeloid leukemia patients, and suggested to correlate with poor prognosis and confer resistance to FLT3 inhibitors. To explore activation mechanism of FLT3 TKD mutation, we analysed critical tyrosine residues for the constitutive activation and downstream signaling of the mutant by generating a series of single Tyr --> Phe substitution mutant of all 22 cytoplasmic tyrosine residues of murine FLT3 TKD-mutant (mFLT3Asp838Val). Tyr845Phe, Tyr892Phe and Tyr922Phe substitutions suppressed the phosphorylation of mFLT3Asp838Val itself, the activation of Erk1/2, STAT3 and STAT5, and the factor-independent cell proliferation and survival. In contrast, these three Tyr --> Phe mutations partially suppressed but maintained the ligand-dependent activation and anti-apoptotic activity of wild-type FLT3, suggesting that these tyrosine residues were more critical for the constitutive activation and signaling of mFLT3Asp838Val. These three Tyr --> Phe mutations also inhibited the constitutive activation of other FLT3 mutants bearing internal tandem duplication, Asp838Tyr or Ile839del. The suppression of mFLT3Asp838Val activation and signaling by these substitutions was partially recovered by shifting the culture temperature from 37 to 33 degrees C, or by the introduction of Cdc37 and Hsp90. Taken together, Tyr845, Tyr892 and Tyr922 are the critical residues in mFLT3Asp838Val activation, possibly through stabilizing the active conformation of mFLT3Asp838Val.

GATA Transcription Factors Inhibit Cytokine-dependent Growth and Survival of a Hematopoietic Cell Line through the Inhibition of STAT3 Activity

Although GATA-1 and GATA-2 were shown to be essential for the development of hematopoietic cells by gene targeting experiments, they were also reported to inhibit the growth of hematopoietic cells. Therefore, in this study, we examined the effects of GATA-1 and GATA-2 on cytokine signals. A tamoxifen-inducible form of GATA-1 (GATA-1/ERT) showed a minor inhibitory effect on interleukin-3 (IL-3)-dependent growth of an IL-3-dependent cell line Ba/F3. On the other hand, it drastically inhibited TPO-dependent growth and gp130-mediated growth/survival of Ba/F3. Similarly, an estradiol-inducible form of GATA-2 (GATA-2/ER) disrupted thrombopoietin (TPO)-dependent growth and gp130-mediated growth/survival of Ba/F3. As for this mechanism, we found that both GATA-1 and GATA-2 directly bound to STAT3 both in vitro and in vivo and inhibited its DNA-binding activity in gel shift assays and chromatin immunoprecipitation assays, whereas they hardly affected STAT5 activity. In addition, endogenous GATA-1 was found to interact with STAT3 in normal megakaryocytes, suggesting that GATA-1 may inhibit STAT3 activity in normal hematopoietic cells. Furthermore, we found that GATA-1 suppressed STAT3 activity through its N-zinc finger domain. Together, these results suggest that, besides the roles as transcription factors, GATA family proteins modulate cytokine signals through protein-protein interactions, thereby regulating the growth and survival of hematopoietic cells.

Distinct role for c-kit receptor tyrosine kinase and SgIGSF adhesion molecule in attachment of mast cells to fibroblasts

Binding of stem cell factor (SCF) to c-kit receptor tyrosine kinase (KIT) transduces signals essential for mast cell development via several pathways including activation of phosphatidylinositol 3-kinase (PI3-K). When cultured mast cells (CMCs) are cocultured with fibroblasts expressing membrane-bound SCF, CMCs with normal KIT adhere to fibroblasts and proliferate, whereas CMCs lacking cell surface expression of KIT do neither. Spermatogenic immunoglobulin superfamily (SgIGSF) was identified as another molecule that participates in mast cell adhesion to fibroblasts. Since the IC-2 mast cell line expressed neither KIT nor SgIGSF, the effect of ectopic expression of KIT or SgIGSF on the adhesion of IC-2 cells was examined. Three forms of KIT with the normal ectodomain were used: wild-type (KIT-WT) and two mutant types with a phenylalanine substitution at the tyrosine residue 719 (KIT-Y719F) or 821 (KIT-Y821F). KIT-Y719F does not activate PI3-K, whereas KIT-Y821F does. Firstly, KIT or SgIGSF was expressed singly in IC-2 cells. All three forms of KIT increased the adhesion level of IC-2 cells, whereas SgIGSF did not. Secondly, SgIGSF was coexpressed with one of the three forms of KIT. Coexpression of SgIGSF with KIT-WT or KIT-Y821F increased the adhesion level more markedly than was achieved by KIT-WT or KIT-Y821F alone. The effect was abolished by an antibody that blocks SCF-KIT interaction. In contrast, coexpression of SgIGSF with KIT-Y719F did not increase the adhesion level induced by KIT-Y719F alone. In adhesion of mast cells to fibroblasts, KIT appeared to behave as an adhesion molecule and as an activator of other adhesion molecules through phosphorylating PI3-K.

Notch signals inhibit the development of erythroid/megakaryocytic cells by suppressing GATA-1 activity through the induction of HES1

The effects of Notch signals on the erythroid/megakaryocytic differentiation of hematopoietic cells were examined. Activation of Notch signals by the intracellular Notch1 or an estradiol-inducible form of Notch1/ER suppressed the expression of the erythroid marker glycophorin A in an erythroid/megakaryocytic cell line K562. Although Mock-transfected K562 cells underwent megakaryocytic differentiation in response to 12-O-tetradecanoylphorbol-13-acetate (TPA), estradiol-activated Notch1/ER induced apoptosis during TPA treatment in the transfectant, which was accompanied by the reduced expression of an antiapoptotic molecule Bcl-XL. Even when apoptosis was prevented by the overexpression of Bcl-XL, activated Notch signals still inhibited TPA-induced megakaryocytic differentiation. As for this mechanism, Notch1/recombination signal binding protein J-kappa-induced HES1 but not HES5 was found to inhibit the function of an erythroid/megakaryocytic lineage-specific transcription factor GATA-1. Although HES1 did not affect the DNA binding activity of GATA-1 in gel shift and chromatin immunoprecipitation assays, it directly bound to GATA-1 and dissociated a critical transcriptional cofactor, p300, from GATA-1. Furthermore, overexpressed HES1 inhibited the development of erythroid and megakaryocytic cells in colony assays. Also, the Notch ligand Jagged1 expressed on NIH3T3 cells suppressed the development of erythroid and megakaryocytic cells from cocultured Lin-Sca-1+ hematopoietic stem/progenitor cells. These results suggest that Notch1 inhibits the development of erythroid/megakaryocytic cells by suppressing GATA-1 activity through HES1.

Roles for c-Myc in self-renewal of hematopoietic stem cells

Notch and HOXB4 have been reported to expand hematopoietic stem cells (HSCs) in vitro. However, their critical effector molecules remain undetermined. We found that the expression of c-myc, cyclin D2, cyclin D3, cyclin E, and E2F1 was induced or enhanced during Notch1- or HOXB4-induced self-renewal of murine HSCs. Since c-Myc can act as a primary regulator of G(1)/S transition, we examined whether c-Myc alone can induce self-renewal of HSCs. In culture with stem cell factor, FLT3 ligand, and IL-6, a 4-hydroxytamoxifen-inducible form of c-Myc (Myc/ERT) enabled murine Lin(-)Sca-1(+) HSCs to proliferate with the surface phenotype compatible with HSCs for more than 28 days. c-Myc activated by 4-hydroxytamoxifen augmented telomerase activities and increased the number of CFU-Mix about 2-fold in colony assays. Also, in reconstitution assays, HSCs expanded by c-Myc could reconstitute hematopoiesis for more than 6 months. As for the mechanism of c-myc induction by Notch1, we found that activated forms of Notch1 (NotchIC) and its downstream effector recombination signal-binding protein-J kappa (RBP-VP16) can activate the c-myc promoter through the element between -195 bp and -161 bp by inducing the DNA-binding complex. Together, these results suggest that c-Myc can support self-renewal of HSCs as a downstream mediator of Notch and HOXB4.

Enhanced production of osteopontin in multiple myeloma: clinical and pathogenic implications

In this study, we examined osteopontin (OPN) production in myeloma cells and plasma OPN levels in multiple myeloma (MM) patients. We assessed OPN production in bone marrow cells (BMCs) by immunocytochemistry and enzyme-linked immunosorbent assay (ELISA). We also assessed OPN production in various B-cell malignant cell lines, including three myeloma cell lines by reverse transcription polymerase chain reaction (RT-PCR) and Western blotting. In addition, we measured plasma OPN concentrations by ELISA in 30 MM patients, 21 monoclonal gammopathy of undetermined significance (MGUS) patients and 30 healthy volunteers. As a result, in an immunocytochemical study, abundant OPN was detected in BMCs from overt MM patients, whereas no OPN was detected in BMCs from patients with other haematological diseases, including MGUS. Cultured BMCs from overt MM patients produced more OPN than those from patients with either smouldering MM or MGUS. Myeloma cell lines spontaneously produced OPN. Plasma OPN levels of MM patients were significantly higher than those of MGUS patients and healthy volunteers (P < 0.05). Moreover, they correlated with both progression and bone destruction of the disease (P < 0.05). These suggest that myeloma cells actively produce OPN, which possibly contributes to osteoclastic bone resorption in MM. Plasma OPN levels may be a useful biomarker for assessing bone destruction in MM and distinguishing MM from MGUS or smouldering MM.

Establishment and characterization of unique cell lines derived from pyothorax-associated lymphoma which develops in long-standing pyothorax and is strongly associated with Epstein-Barr virus infection

Malignant lymphoma frequently develops in the pleural cavity of patients with over 20 years' history of pyothorax. The term pyothorax-associated lymphoma (PAL) has been proposed for this type of tumor. We established four novel lymphoma cell lines (OPL-3, -4, -5, and -7) from four patients with PAL. Characteristics of the four cell lines are as follows: B-cell nature with defective expression of B-cell and T-cell surface antigens, monoclonal pattern of Epstein-Barr virus (EBV) infection in lymphoma cells (thus indicating an etiological role of EBV for lymphomagenesis), complicated chromosomal abnormalities with numerous structural and numerical abnormalities, and occasional but distinct genome instability. These abnormalities in cell character might be caused by the specific circumstances of PAL lymphomagenesis, i.e., chronic inflammation. Thus, PAL cell lines could be useful in analysis of molecular mechanisms leading to malignancy in chronic inflammation.

Oncogenic receptor tyrosine kinase in leukemia

Growth, survival and differentiation of hematopoietic cells are regulated by the interaction between hematopoietic growth factors and their receptors. While the defect in this interaction results in an insufficient hematopoiesis, the aberrantly elevated activation leads to the transformation of hematopoietic cells. The constitutive active mutations of receptor tyrosine kinase, such as c-Kit platelet-derived growth factor receptor (PDGFR) or fins-like tyrosine kinase 3 (Flt3), play a major role in the development of hematopoietic neoplasia. The constitutive activation is provoked by several mechanisms, such as making fusion genes by chromosomal translocations, or various mutations involving regulatory regions of the receptor. The chromosomal translocation brings the receptor intracytoplasmic domain juxtaposed to an unrelated molecule which has dimerization or multimerization motif, resulting in the constitutive dimerization of the receptor. The missense, insertion or deletion mutations in the regulatory regions, such as juxtamembrane domain, activation loop and extracellular domain, cause constitutive activation by releasing the respective auto-inhibitory functions of each regulatory region. Constitutive active receptors generate different signals quantitatively and qualitatively from wild type receptor, which mediate the oncogenic phenotype. Given the frequent involvement of constitutive active receptor tyrosine kinase in hematopoietic malignancies, targeted inhibitions of active tyrosine kinase and downstream aberrant signaling are rapidly developing novel therapeutic modality with much promise.

Suppression of myeloid transcription factors and induction of STAT response genes by AML-specific Flt3 mutations

The receptor tyrosine kinase Flt3 is expressed and functionally important in early myeloid progenitor cells and in the majority of acute myeloid leukemia (AML) blasts. Internal tandem duplications (ITDs) in the juxtamembrane domain of the receptor occur in 25% of AML cases. Previously, we have shown that these mutations activate the receptor and induce leukemic transformation. In this study, we performed genome-wide parallel expression analyses of 32Dcl3 cells stably transfected with either wild-type or 3 different ITD isoforms of Flt3. Comparison of microarray expression analyses revealed that 767 of 6586 genes differed in expression between FLT3-WT- and FLT3-ITD-expressing cell lines. The target genes of mutationally activated Flt3 resembled more closely those of the interleukin 3 (IL-3) receptor than those of ligand-activated Flt3. The serine-threonine kinase Pim-2 was up-regulated on the mRNA and the protein level in Flt3-ITD-expressing cells. Further experiments indicated that Pim-2 function was important for clonal growth of 32D cells. Several genes repressed by the mutations were found to be involved in myeloid gene regulation. Pu.1 and C/EBPalpha, both induced by ligand-activation of wild-type Flt3, were suppressed in their expression and function by the Flt3 mutations. In conclusion, internal tandem duplication mutations of Flt3 activate transcriptional programs that partially mimic IL-3 activity. Interestingly, other parts of the transcriptional program involve novel, IL-3-independent pathways that antagonize differentiation-inducing effects of wild-type Flt3. The identification of the transcriptional program induced by ITD mutations should ease the development of specific therapies.

Constitutively activated Rho guanosine triphosphatases regulate the growth and morphology of hairy cell leukemia cells

Hairy cell leukemia (HCL) is a rare type of chronic B-cell leukemia characterized by the hairy morphology of the leukemia cells. All of 5 HCL samples and an HCL-derived cell line, BNBH-I, showed serrated edges and hairlike projections in May-Grünwald Giemsa stain and protruding actin spikes and lamellipodia in phalloidin stain. These structures were hardly detected on B-cell chronic lymphocytic leukemia (B-CLL) and precursor B-cell acute lymphocytic leukemia (B-ALL) cells. Because Rho guanosine triphosphatases (GTPases) regulate the formation of these structures, we examined the expression levels and activation states of Rho GTPases in HCL cells. RhoA, Rac1, and Cdc42 were overexpressed and constitutively activated in HCL samples and BNBH-I cells but not in B-CLL or precursor B-ALL cells. Next we overexpressed dominant-negative (DN)-RhoA, DN-Rac1, and DN-Cdc42 in BNBH-I. As a result, each DN mutant repressed the growth of BNBH-I cells by more than 50% and inhibited actin spike formation, but only DN-Racl suppressed lamellipodia formation. We also found that enforced expression of constitutively active-RhoA, Rac, or Cdc42 in the proB-cell line Ba/F3 was sufficient to induce actin spike formation, whereas none of these molecules produced lamellipodia. These results indicated that constitutively activated Rho GTPases regulate the growth and unique morphology of HCL cells.

Necessity of tyrosine 719 and phosphatidylinositol 3'-kinase-mediated signal pathway in constitutive activation and oncogenic potential of c-kit receptor tyrosine kinase with the Asp814Val mutation

Substitution of valine (Val) for aspartic acid (Asp) at codon 814 constitutively activates murine c-kit receptor tyrosine kinase (KIT), and Asp816Val mutation, corresponding to murine Asp814Val mutation, is found in patients with mastocytosis and acute myelocytic leukemia. However, the signal transduction pathways responsible for oncogenesis by the Asp814Val mutant (KIT(Val814)) are not fully understood. To examine the oncogenic signal transduction of KIT(Val814), we converted 20 tyrosine (Tyr) residues to phenylalanine (Phe) in the cytoplasmic domain of KIT(Val814) or deleted the C-terminal region containing 2 other tyrosine residues (Del). Among various KIT(Val814)- derived mutants, KIT(Val814-Tyr719Phe) and KIT(Val814-Del) severely impaired receptor tyrosine phosphorylation and association with the p85 subunit of phosphatidylinositol 3'-kinase (p85 (PI3-K)). Moreover, KIT(Val814-Tyr719Phe) and KIT(Val814-Del) failed to induce ligand-independent growth in Ba/F3 cells, indicating that Tyr719, the binding site for p85(PI3-K), and the C-terminal region are indispensable for factor-independent growth by KIT(Val814). Although the C-terminal region was also required for ligand-dependent growth by wild-type KIT (KIT(WT)), the Tyr719Phe substitution had negligible effects on ligand-dependent growth by KIT(WT). Furthermore, dominant-negative PI3-K significantly inhibited ligand-independent growth by KIT(Val814). These results demonstrate that Tyr719 is crucial for constitutive activation of KIT(Val814), but not for the ligand-induced activation of KIT(WT), and that the downstream signaling of PI3-K plays an important role in ligand-independent growth and tumorigenicity by KIT(Val814), thereby suggesting that KIT(Val814) is a unique activating mutation that leads to a distinguishable function from the effects of KIT(WT).

Constitutive activation of c-kit by the juxtamembrane but not the catalytic domain mutations is inhibited selectively by tyrosine kinase inhibitors STI571 and AG1296

The c-kit receptor tyrosine kinase (KIT) is constitutively activated by 2 types of naturally occurring mutations, the Val559-->Gly (G559) mutation in the juxtamembrane domain and the Asp814-->Val (V814) mutation in the catalytic domain. We evaluated the effects of the tyrosine kinase inhibitors STI571 and AG1296 on BaF3 cells expressing wild-type KIT (KIT(WT)) or activating mutants of KIT (KIT(G559) and KIT(V814)) in the presence or absence of the KIT ligand, stem cell factor (SCF). Both STI571 and AG1296 inhibited SCF-dependent activation of KIT(WT) and SCF-independent activation of KIT(G559) more efficiently, whereas SCF-independent activation of KIT(V814) was scarcely affected. Furthermore, both inhibitors inhibited SCF-dependent growth of BaF3-KIT(WT) cells and, with higher potencies, SCF-independent growth of BaF3-KIT(G559) cells through the induction of apoptosis. In contrast, the inhibitors had little or no effect on SCF-independent growth of BaF3-KIT(V814) cells or on IL-3-dependent growth of BaF3-Mock cells. These results suggested that both inhibitors may be effective therapeutic agents for oncogenic KIT with the juxtamembrane domain mutation, but not with the catalytic domain mutation, and that the activation mechanism of the catalytic domain mutant KIT is complex and entirely different from that of the wild-type KIT or the juxtamembrane domain mutant KIT.

[Mutations of growth factor receptor Flt3 in acute myeloid leukemia: transformation of myeloid cells by Ras-dependent and Ras-independent mechanisms]

BACKGROUND AND OBJECTIVE

The tyrosine kinase receptor Flt3 mediates important functions in early hematopoietic progenitors. Recently mutations of a growth factor receptor have been identified in about 30 % of patients with acute myeloid leukemia (AML). These mutations are associated with a poor prognosis. In-vitro and animal data show their involvement in leukemic transformation. Experiments analyzing the effects of these mutations on signal transduction and gene expression patterns of myeloid cells allow for the classification of this receptor as an oncogene. Furthermore, they help to define the receptor and its signaling intermediates as therapeutic targets.

METHODS

In order to analyze the signaling properties of mutated FLT3 receptors, we isolated the receptor mRNA from two patients with AML. Wild-type and mutant Flt3 isoforms were expressed in 32D cells that were subsequently analyzed for proliferation, survival, activation of signaling intermediates and gene expression levels. Also, the effects of of Ras-, MAP-Kinase and PI3-Kinase inhibition were analyzed.

RESULTS

The expression of mutated Flt3 (Flt3-ITD) induced factor-independent proliferation and survival in the myeloid progenitor cell line 32D. Flt3-ITD activated Ras- and PI3-kinase-dependent signaling pathways, as well as STAT5 and STAT3. Activation of STAT proteins was followed by the induction of known STAT target genes like SOCS2, SOCS3 and CIS. Inhibition of Ras-dependent signal transduction by a dominant negative Ras construct inhibited some, but not all biological effects of Flt3-ITD. Similar results were obtained by chemical inhibition of the MAP kinases. In contrast, inhibition of PI3 kinase activity inhibited growth factor-independent growth and apoptosis resistance of 32D cells.

CONCLUSIONS

Inhibition of Ras-dependent signaling pathways is not sufficient to abrogate the functional consequences of Flt3-mutations in myeloid cells. Therefore, therapeutic intervention by Ras-Inhibitors may not be sufficient to treat Flt3-driven disease.

Critical roles of c-Kit tyrosine residues 567 and 719 in stem cell factor-induced chemotaxis: contribution of src family kinase and PI3-kinase on calcium mobilization and cell migration

Stem cell factor (SCF) has crucial roles in proliferation, survival, and differentiation of hematopoietic stem cells and mast cells through binding to c-Kit receptor (KIT). Chemotaxis is another unique function of SCF. However, little is known about the intracellular signaling pathway of SCF/KIT-mediated cell migration. To investigate the signaling cascade, we made a series of 22 KIT mutants, in which tyrosine (Y) residue was substituted for phenylalanine (F) in the cytoplasmic domain, and introduced into BAF3 cells or 293T cells. On stimulation with SCF, BAF3 expressing KIT(WT)(WT) showed cell migration and Ca(2+) mobilization. Among 22 YF mutants, Y567F, Y569F, and Y719F showed significantly reduced cell migration and Ca(2+) mobilization compared to WT. In Y567F, Lyn activation on SCF stimulation decreased and C-terminal Src kinase (Csk) suppressed KIT-mediated Ca(2+) influx and cell migration, suggesting that Y567-mediated Src family kinase (SFK) activation leads to Ca(2+) influx and migration. Furthermore, we found that p38 mitogen-activated protein kinase (p38 MAPK) and Erk1/2 were also regulated by Y567/SFK and involved in cell migration, and that p38 MAPK induced Ca(2+) influx, thereby leading to Erk1/2 activation. In Y719F, the binding of phosphatidylinositol 3'-kinase (PI3K) to KIT was lost and KIT-mediated cell migration and Ca(2+) mobilization were suppressed by PI3K chemical inhibitors or dominant-negative PI3K, suggesting the involvement of Y719-mediated PI3K pathway in cell migration. Combination of Csk and the PI3K inhibitor synergistically reduced cell migration, suggesting the cooperation of SFK and PI3K. Taken together, these results indicate that 2 major KIT signaling pathways lead to cell migration, one is Y567-SFK-p38 MAPK-Ca(2+) influx-Erk and the other is Y719-PI3K-Ca(2+) influx.

Functional cooperation among Ras, STAT5, and phosphatidylinositol 3-kinase is required for full oncogenic activities of BCR/ABL in K562 cells

BCR/ABL tyrosine kinase generated from the chromosomal translocation t(9;22) causes chronic myelogenous leukemia and acute lymphoblastic leukemia. To examine the roles of BCR/ABL-activated individual signaling molecules and their cooperation in leukemogenesis, we inducibly expressed a dominant negative (DN) form of Ras, phosphatidylinositol 3-kinase, and STAT5 alone or in combination in p210 BCR/ABL-positive K562 cells. The inducibly expressed DN Ras (N17), STAT5 (694F), and DN phosphatidylinositol 3-kinase (Delta p85) inhibited the growth by 90, 55, and 40%, respectively. During the growth inhibition, the expression of cyclin D2 and cyclin D3 was suppressed by N17, 694F, or Delta p85; that of cyclin E by N17; and that of cyclin A by Delta p85. In addition, N17 induced apoptosis in a small proportion of K562, whereas 694F and Delta p85 were hardly effective. In contrast, coexpression of two DN mutants in any combinations induced severe apoptosis. During these cultures, the expression of Bcl-2 was suppressed by N17, 694F, or Delta p85, and that of Bcl-XL by N17. Furthermore, although K562 was resistant to interferon-alpha- and dexamethasone-induced apoptosis, disruption of one pathway by N17, 694F, or Delta p85 sensitized K562 to these reagents. These results suggested that cooperation among these molecules is required for full leukemogenic activities of BCR/ABL.

Interference between host resistance to Listeria monocytogenes infection and ovalbumin-induced allergic responses in mice

Listeria monocytogenes promotes the induction of the T-helper 1 (Th1) cell response, while ovalbumin (OVA) induces a Th2 cell response and allergic reactions, such as airway hyperreactivity and immunoglobulin E (IgE) production. When mice were immunized with OVA on day 7 after L. monocytogenes infection, eosinophilia in bronchoalveolar lavage and the production of total IgE, OVA-specific IgE, interleukin-4 (IL-4), and IL-5 in the circulation were markedly suppressed. Cytokine responses, including IL-4, IL-5, IL-10, IL-13, and gamma interferon, to OVA were decreased in the spleen cell cultures obtained from OVA-immunized mice that had been infected with L. monocytogenes. Conversely, when OVA-immunized mice were infected with L. monocytogenes, conversion from the nonlethal infection to the lethal infection occurred. Host resistance to L. monocytogenes infection in OVA-immunized mice was enhanced by the administration of anti-IL-10 monoclonal antibody. The present study indicates that striking interference is observed between Th1-inducing L. monocytogenes infection and Th2-driven OVA-induced airway hyperreactivity.

[Relationship between atopic factors and physical symptoms induced by gaseous formaldehyde exposure during an anatomy dissection course]

Formaldehyde (FA) is an occupational and general indoor hazard often affecting the respiratory airways. One of the main causes of multiple chemical sensitivity is gaseous FA, and it has become an important social problem in developed countries. FA concentrations in anatomy dissection classrooms are thought to be higher than under usual circumstances. The number of students developing physical symptoms during the anatomy dissection course in our university has been increasing over recent years. We planned to clarify the causes of such symptoms. Ninety-five medical students were interviewed using a questionnaire about allergic histories, physical symptoms developed during the anatomy dissection course, and symptoms related to chemical sensitivity up to three months after the course had finished. We measured total IgE, specific IgE to FA and specific IgE to house dust mites. Eighty-three percent of students had experienced symptoms, such as burning eyes, nasal discharge, sore throat, general fatigue or skin irritation during the course. Fifty percent of students had a past history of atopic disease. Fifty-eight percent of students tested positive to specific IgE to house dust mites; however, only one student, who did not complain of any symptoms during the course, tested positive to FA-IgE. Students with atopic factors (present histories of atopic diseases and higher total IgE) and/or chemical sensitivity demonstrated worse physical symptoms during the anatomy dissection course than students without such histories. In conclusion, it is suggested that gaseous FA exposure may exacerbate basic allergic symptoms, and moreover that people with chemical sensitivity demonstrated worse symptoms following gaseous FA exposure. Nevertheless, in our study we find no relationship between FA-IgE and the physical symptoms of gaseous FA exposure during or following an anatomy dissection course.

Flt3 mutations from patients with acute myeloid leukemia induce transformation of 32D cells mediated by the Ras and STAT5 pathways

Somatic mutations of the receptor tyrosine kinase Flt3 consisting of internal tandem duplications (ITD) occur in 20% of patients with acute myeloid leukemia. They are associated with a poor prognosis of the disease. In this study, we characterized the oncogenic potential and signaling properties of Flt3 mutations. We constructed chimeric molecules that consisted of the murine Flt3 backbone and a 510-base pair human Flt3 fragment, which contained either 4 different ITD mutants or the wild-type coding sequence. Flt3 isoforms containing ITD mutations (Flt3-ITD) induced factor-independent growth and resistance to radiation-induced apoptosis in 32D cells. Cells containing Flt3-ITD, but not those containing wild-type Flt3 (Flt3-WT), formed colonies in methylcellulose. Injection of 32D/Flt3-ITD induced rapid development of a leukemia-type disease in syngeneic mice. Flt3-ITD mutations exhibited constitutive autophosphorylation of the immature form of the Flt3 receptor. Analysis of the involved signal transduction pathways revealed that Flt3-ITD only slightly activated the MAP kinases Erk1 and 2 and the protein kinase B (Akt) in the absence of ligand and retained ligand-induced activation of these enzymes. However, Flt3-ITD led to strong factor-independent activation of STAT5. The relative importance of the STAT5 and Ras pathways for ITD-induced colony formation was assessed by transfection of dominant negative (dn) forms of these proteins: transfection of dnSTAT5 inhibited colony formation by 50%. Despite its weak constitutive activation by Flt3-ITD, dnRas also strongly inhibited Flt3-ITD-mediated colony formation. Taken together, Flt3-ITD mutations induce factor-independent growth and leukemogenesis of 32D cells that are mediated by the Ras and STAT5 pathways. (Blood. 2000;96:3907-3914)

Roles of endogenous cytokines in liver apoptosis of mice in lethal Listeria monocytogenes infection

Various bacterial pathogens have been identified as mediators of apoptosis. Apoptosis reportedly shows both detrimental and beneficial effects on biological functions. We studied the role of liver apoptosis in lethal Listeria monocytogenes infection and the regulation of apoptosis by endogenous cytokines during infection. Apoptosis was observed in the spleen but not in the liver of infected mice, whereas the induction of liver necrosis was evident by rising levels of serum aminotransferases in these animals. Apoptosis was detected in the liver of L. monocytogenes-infected mice which had been treated with monoclonal antibody (mAb) against tumor necrosis factor-alpha (TNF-alpha) or interleukin-6 (IL-6), or in TNF-alpha(-/-) mice, but not in gamma- interferon (IFN-gamma)(-/-) mice or mice which had been treated with mAb against IL-4 or IL-10. Augmentation of liver apoptosis in mice treated with mAb against TNF-alpha or IL-6 or in TNF-alpha(-/-) mice correlated with the increase in bacterial numbers in the organ, while no augmentation of apoptosis was observed in the liver of IFN-gamma(-/-) mice irrespective of the marked increase in bacterial numbers in the organs, indicating that augmentation of liver apoptosis may not be merely due to the increase in bacterial growth in the organs. These results suggest that TNF-alpha and IL-6 may play an important role in protecting the liver from apoptosis in lethal L. monocytogenes infection.

Interleukin-4 and interleukin-10 are involved in host resistance to Staphylococcus aureus infection through regulation of gamma interferon

Our previous study showed that gamma interferon (IFN-gamma), a T-helper 1 (Th1)-type cytokine, plays a detrimental role in Staphylococcus aureus infection in mice. In this study, the role of Th2-type cytokines such as interleukin-4 (IL-4) and IL-10 in S. aureus infection was investigated. IL-10 mRNA was induced in parallel with IFN-gamma in the spleens and kidneys of mice during S. aureus infection, whereas IL-4 mRNA was induced in the spleens but not in the kidneys of these animals. Spleen cells obtained from S. aureus-infected mice produced lower titers of IFN-gamma and higher titers of IL-4 and IL-10 in response to heat-killed S. aureus than did those from uninfected mice. Administration of anti-IL-4 monoclonal antibody (MAb) or anti-IL-10 MAb inhibited the elimination of S. aureus cells from the kidneys of mice. IFN-gamma mRNA expression was enhanced in the spleens of anti-IL-4 MAb- or anti-IL-10 MAb-treated mice and also in the kidneys of anti-IL-4 MAb-treated animals. Next, we evaluated the role of IFN-gamma in S. aureus infection in IFN-gamma(-/-) mice. An increase in survival rates, a decrease in bacterial numbers in the kidneys, and an amelioration of histologic abnormalities in these organs were observed in IFN-gamma(-/-) mice compared with those in IFN-gamma(+/+) mice. Administration of MAb against IL-4 or IL-10 failed to affect bacterial growth in the spleens and kidneys of IFN-gamma(-/-) mice irrespective of the expression of Th2 response. These results suggest that S. aureus infection induced a Th2 response and that IL-4 and IL-10 might play a protective role through the regulation of IFN-gamma in S. aureus infection.

Altered expression of natural killer cell inhibitory receptors (KIRs) on T cells in bronchoalveolar lavage fluid and peripheral blood of sarcoidosis patients

BACKGROUND AND AIM OF THE WORK

The role for natural killer cell inhibitory receptors (KIRs) on T cells is not fully understood, but signalling through KIRs on T cells may inhibit T cell receptor mediated activation, and KIR expression has been suggested to be one mechanism of controlling T cell mediated immune responses. An aberrant KIR expression on T cells could thus be of importance in autoimmune as well as infectious disorders. Sarcoidosis patients have several immunological impairments that have not been clarified, and we here examined the KIR expression on CD4+ and CD8+ peripheral blood (PBL) and bronchoalveolar lavage (BAL) T cells of sarcoidosis patients and controls.

METHODS

We used three KIR specific monoclonal antibodies, namely DX9 (specific for p70), DX27 (p58) and DX22 (specific for CD94, that belongs to another major group of KIRs) and flow cytometry.

RESULTS

p70 was expressed lower in patient CD8+ PBL (median 2.3%) compared to controls (6.3%) (p < 0.01). In patients, p58 was expressed by less CD8+ BAL lymphocytes (median 1.2%) compared to PBL (6.8%) (p < 0.01) while CD94 was expressed by more CD8+ BAL lymphocytes (median 14.5%) compared to PBL (9.6%) (p < 0.01). Moreover, in CD8+ PBL, CD94 and p58 were expressed significantly lower in patients with an active vs. inactive disease, and in patients with chest radiographic stage I vs. stage II, respectively.

CONCLUSIONS

The significantly altered expression of distinct KIRs on CD8+ T cells in sarcoidosis, especially in patients with signs of an active disease, indicate these cells to be dysregulated and implicate them in the pathogenesis of the disease.

Constitutive activation of FLT3 in acute myeloid leukaemia and its consequences for growth of 32D cells

The receptor tyrosine kinase Flt3 is expressed on leukaemic blasts of most cases with acute myeloid leukaemia (AML). In order to evaluate the presence and significance of constitutive activation of Flt3 for leukaemogenesis, we (1) analysed the expression and activation status of the receptor in AML blasts; and (2) evaluated the functional consequences of constitutively active Flt3 in a myeloid progenitor cell line. Immunoprecipitation studies revealed Flt3 expression in a high proportion of AML cases (27/32) with ligand-dependent Flt3 autophosphorylation in 18, constitutive autophosphorylation in three and no autophosphorylation in six cases. Only one out of three samples with constitutively active Flt3 but 3/18 samples with ligand-dependent autophosphorylated Flt3 contained the recently described internal tandem repeat (ITR) mutations. To test the significance of Flt3 activation in myeloid cell function, we also characterized the biochemical and biological effects of the activating mutation D838V of Flt3 (FLt3D838V) on the factor-dependent myeloid progenitor cell line 32Dcl3: cells transfected with wild-type Flt3 (32D/Flt3) grew FLt3 ligand (FL) dependent, and the receptor was ligand dependently autophosphorylated. In contrast, the receptor was constitutively autophosphorylated in 32D/Flt3D838V cells, which grew independently of FL. We conclude that, in some AML samples, Flt3 is constitutively activated and that this does not correlate with ITR mutations in the juxtamembrane domain. Furthermore, constitutively active Flt3 confers factor independence to the myeloid progenitor cell line 32D. It remains to be determined whether activation of Flt3 is leukaemogenic in vivo and whether strategies aimed at inhibition of Flt3 activation could inhibit leukaemogenesis.