Cytarabine-induced differentiation of AML cells depends on Chk1 activation and shares the mechanism with inhibitors of DHODH and pyrimidine synthesis.

Acute myeloid leukemia (AML) is characterized by arrested differentiation making differentiation therapy a promising treatment strategy. Recent success of inhibitors of mutated isocitrate dehydrogenase (IDH) invigorated interest in differentiation therapy of AML so that several new drugs have been proposed, including inhibitors of dihydroorotate dehydrogenase (DHODH), an enzyme in pyrimidine synthesis. Cytarabine, a backbone of standard AML therapy, is known to induce differentiation at low doses, but the mechanism is not completely elucidated. We have previously reported that 5-aminoimidazole-4-carboxamide ribonucleoside (AICAr) and brequinar, a DHODH inhibitor, induced differentiation of myeloid leukemia by activating the ataxia telangiectasia and Rad3-related (ATR)/checkpoint kinase 1 (Chk1) via pyrimidine depletion. In this study, using immunoblotting, flow cytometry analyses, pharmacologic inhibitors and genetic inactivation of Chk1 in myeloid leukemia cell lines, we show that low dose cytarabine induces differentiation by activating Chk1. In addition, cytarabine induces differentiation ex vivo in a subset of primary AML samples that are sensitive to AICAr and DHODH inhibitor. The results of our study suggest that leukemic cell differentiation stimulated by low doses of cytarabine depends on the activation of Chk1 and thus shares the same pathway as pyrimidine synthesis inhibitors.

Bendamustine: A review of pharmacology, clinical use and immunological effects (Review).

Bendamustine is an alkylating agent classified into the group of nitrogen mustard analogues, synthesized almost sixty years ago. It was registered in former East Germany in 1971 and approved by the US Food and Drug Administration in 2008 for treatment of chronic lymphocytic leukemia and indolent B­cell non­Hodgkin lymphoma. Considering its beneficial properties in the therapy of relapsed or refractory hematological malignancies, synergistic effects with other antineoplastic agents and increasing recent reports on its immunomodulatory effects, bendamustine has once again gained its justified attention. The uniqueness of bendamustine­mediated effects should be observed keeping in mind its distinctive structure with structural similarities to both alkylating agents and purine analogs. In the present review, the current knowledge on the use of bendamustine in oncology, its pharmacokinetics, mechanism of action and toxicity was summarized. In addition, its immune­modulating effects that have not been fully elucidated so far are emphasized, hoping to encourage further investigations of this unique drug.

2019 ACR/EULAR classification criteria and therapy in predicting organ damage accrual in patients with childhood-onset systemic lupus erythematosus: A retrospective study over the last 29 years.

OBJECTIVE: We explored damage occurrence in patients with childhood-onset SLE (cSLE) and aimed to predict the risk of organ damage occurrence in time. METHODS: The retrospective study included patients treated for cSLE at the Centre of Reference for Pediatric and Adolescent Rheumatology of the Republic Croatia over a 29-year period. RESULTS: The disease development of 97 patients (77 females) with cSLE was examined. The median (Q1, Q3) follow-up time was 6.5 (2.3, 12.0) years. SDI was determined at 5 time points (6, 12, 24, 36 months, and last follow-up). Thirty-eight patients (48%) had organ damage at the last follow-up. Prepubertal group of patients showed higher SLEDAI scores at the disease onset, while post-pubertal group had significantly lower proportion of patients with relapses. We estimated the time from the first symptom to the moment of damage and our findings suggest that it is unlikely that organ damage will occur in 50% of patients in the first 6 years since the diagnosis. The number of 2019 ACR/EULAR classification criteria at the time of diagnosis associated with SDI determined after 1 year of the follow-up period. The patients who received higher doses of glucocorticoids accumulated damage faster and mycophenolate mofetil was found to be a more frequent therapy in patients with SDI ≥3. CONCLUSION: Knowing that damage will most likely happen after the first 6 years after diagnosis in 50% of patients enables physicians to better predict damage occurrence. High number of 2019 ACR/EULAR criteria and treatment with glucocorticoids in childhood-onset SLE are associated with damage accrual and these findings could enable us to detect patients which should be closely monitored for higher risk of damage development.

All-trans retinoic acid induces differentiation in primary acute myeloid leukemia blasts carrying an inversion of chromosome 16.

All-trans retinoic acid (ATRA)-based therapy for acute promyelocytic leukemia (APL), a subtype of acute myeloid leukemia (AML), is the most successful example of differentiation therapy. Although ATRA can induce differentiation in some non-APL AML cell lines and primary blasts, clinical results of adding ATRA to standard therapy in non-APL AML patients have been inconsistent, probably due to use of different regimens and lack of diagnostic tools for identifying which patients may be sensitive to ATRA. In this study, we exposed primary blasts obtained from non-APL AML patients to ATRA to test for differentiation potential in vitro. We observed increased expression of differentiation markers, indicating a response to ATRA, in four out of fifteen primary AML samples. Three samples in which CD11b increased in response to ATRA had an inversion of chromosome 16 as well as the CBFB-MYH11 fusion gene, and the fourth sample was from a patient with KMT2A-rearranged, therapy-related AML. In conclusion, we identified a subgroup of non-APL AML patients with inv(16) and CBFB-MYH11 as the most sensitive to ATRA-mediated differentiation in vitro, and our results can help identify patients who may benefit from ATRA treatment.

An Extensive Quality Control and Quality Assurance (QC/QA) Program Significantly Improves Inter-Laboratory Concordance Rates of Flow-Cytometric Minimal Residual Disease Assessment in Acute Lymphoblastic Leukemia: An I-BFM-FLOW-Network Report.

Monitoring of minimal residual disease (MRD) by flow cytometry (FCM) is a powerful prognostic tool for predicting outcomes in acute lymphoblastic leukemia (ALL). To apply FCM-MRD in large, collaborative trials, dedicated laboratory staff must be educated to concordantly high levels of expertise and their performance quality should be continuously monitored. We sought to install a unique and comprehensive training and quality control (QC) program involving a large number of reference laboratories within the international Berlin-Frankfurt-Münster (I-BFM) consortium, in order to complement the standardization of the methodology with an educational component and persistent quality control measures. Our QC and quality assurance (QA) program is based on four major cornerstones: (i) a twinning maturation program, (ii) obligatory participation in external QA programs (spiked sample send around, United Kingdom National External Quality Assessment Service (UK NEQAS)), (iii) regular participation in list-mode-data (LMD) file ring trials (FCM data file send arounds), and (iv) surveys of independent data derived from trial results. We demonstrate that the training of laboratories using experienced twinning partners, along with continuous educational feedback significantly improves the performance of laboratories in detecting and quantifying MRD in pediatric ALL patients. Overall, our extensive education and quality control program improved inter-laboratory concordance rates of FCM-MRD assessments and ultimately led to a very high conformity of risk estimates in independent patient cohorts.

Properties of Uncommon Indirect Immunofluorescence Staining Patterns Determined during Antinuclear Antibody Detection on HEp-2 Cells.

In this study, we aimed to assess the prevalence of uncommon staining patterns found during testing for the presence of antinuclear antibodies (ANA) and to determine their association with certain antibodies and clinical diagnoses. Presence of ANA and the staining pattern was determined in 10955 samples using indirect immunofluorescence (IIF) on HEp-2 cells. ANA-positive samples were assessed for presence of 14 specific antibody types using a microbead based system. Demographic data (age, sex) and clinical diagnoses were collected from the referral documentation. Particular staining patterns were then compared with a representative comparison group comprised of samples with common staining patterns using these criteria. There were 22 patterns present in less than 3% of samples each and these were jointly present in 42.43% of ANA-positive samples. Specific antibodies were found in proportions similar to the comparison group (46.06%) and varied significantly between patterns. Likewise, there were significant differences in antibody distribution in particular patterns. Some patterns were associated with presence of rheumatic diseases or inflammatory arthropathies, while in others there was a concurrent diagnosis of liver disease, or a neoplastic process. Many of the uncommon IIF patterns have distinctive characteristics that warrant further investigation in order to determine their role in diagnosing various diseases, not limited only to the illnesses of the rheumatic spectrum. IIF on HEp-2 cells remains an irreplaceable method because of the diversity of ANA, only a number of which can be detected using other standardised methods.

B regulatory cells and monocyte subpopulations in patients with chronic graft-vs-host disease.

AIM: To assess the correlations of B regulatory cells (Bregs) and monocyte subsets in peripheral blood with the National Institutes of Health (NIH)-consensus-defined clinical manifestations of chronic graft-vs-host disease (cGvHD), in an attempt to establish their role as cellular biomarkers. METHODS: This multidisciplinary prospective study enrolled adult cGVHD patients treated in the University Hospital Center Zagreb and University of Zagreb School of Medicine. Immunophenotypic subpopulations of CD24highCD38high Bregs (CD27-, CD27+, and total) and monocyte (classical, intermediate, and non-classical) counts were correlated with demographic, transplant, and cGVHD-related data. Bivariate correlation analysis was performed to evaluate the correlations between Bregs and monocytes subsets and cGVHD organ involvement, as well as cGVHD severity and immunosuppression intensity. RESULTS: Twenty-two adult patients (54.5% female) with cGVHD were enrolled. The median (range) age was 44.5 years (24-65). All patients were transplanted for hematologic malignancies and 40.9% had severe NIH cGVHD global score. The median time from cGVHD diagnosis to the analysis was 16.6 months (0-176). The organ most frequently affected with cGVHD were the eyes (68.2%), skin (45.5%), lungs (45.5%), and liver (40.9%). Lower total and CD27-Bregs counts were correlated with worse cGVHD severity, higher immunosuppression intensity, and lung cGVHD, in terms of cell count, but also with skin cGVHD, in terms of percentages. Patients with liver and joint/fascia cGVHD had a lower percentage of non-classical monocytes and patients with more severe global NIH score had a higher classical monocytes count. CONCLUSION: Different organs affected by cGVHD are differently associated with different subpopulations of Bregs and monocytes.

Influence of delaying ocrelizumab dosing in multiple sclerosis due to COVID-19 pandemics on clinical and laboratory effectiveness.

OBJECTIVE: To evaluate clinical and laboratory effects of delaying ocrelizumab infusions during the COVID-19 pandemics in people with multiple sclerosis (pwMS). METHODS: We have retrospectively searched our electronic database and identified 33 pwMS who had a delay in treatment due to COVID-19 pandemics. The following data were extracted: age, sex, multiple sclerosis (MS) phenotype: relapsing-remitting (RRMS) or primary progressive multiple sclerosis (PPMS), disease duration, Expanded Disability Status scale (EDSS), previous disease modifying therapy (DMT), number of ocrelizumab cycles prior to the lockdown, dates of first ocrelizumab infusion, last ocrelizumab infusion prior to the lockdown and delayed ocrelizumab infusion after the lockdown. Flow cytometry results, relapses and EDSS progression prior to the delayed ocrelizumab infusion after the lockdown were extracted. RESULTS: The mean time between two ocrelizumab infusion during the lockdown was 7.72±0.64 (range 6.07 to 8.92) months. The mean time between last ocrelizumab infusion and the lymphocyte sampling prior to post COVID infusion was 6.59±0.95 (range 5.18 to 8.49) months. In this period, none of the studied patients had a relapse. In a multivariable linear regression analysis, time from last ocrelizumab infusion to lymphocyte sampling prior to the next infusion was the only significant predictor for CD19+ B cells count, when corrected for the number of previous ocrelizumab cycles and MS phenotype (RRMS or PPMS) (B=7.981, 95% C.I. 3.277-12.686, p=0.002). CONCLUSIONS: We have not shown clinical consequences of delaying ocrelizumab due to COVID-19 pandemics. However, the delay in dosing of ocrelizumab was an independent predictor of repopulation of B cells.

5-aminoimidazole-4-carboxamide ribonucleoside induces differentiation in a subset of primary acute myeloid leukemia blasts.

BACKGROUND: All-trans retinoic acid (ATRA)-based treatment of acute promyelocytic leukemia (APL) is the most successful pharmacological treatment of acute myeloid leukemia (AML). Recent development of inhibitors of mutated isocitrate dehydrogenase and dihydroorotate dehydrogenase (DHODH) has revived interest in differentiation therapy of non-APL AML. Our previous studies demonstrated that 5-aminoimidazole-4-carboxamide ribonucleoside (AICAr) induced differentiation of monocytic cell lines by activating the ATR/Chk1 via pyrimidine depletion. In the present study, the effects of AICAr on the viability and differentiation of primary AML blasts isolated from bone marrow of patients with non-APL AML were tested and compared with the effects of DHODH inhibitor brequinar and ATRA. METHODS: Bone marrow samples were obtained from 35 patients and leukemia blasts were cultured ex vivo. The cell viability was assessed by MTT assay and AML cell differentiation was determined by flow cytometry and morphological analyses. RNA sequencing and partial data analysis were conducted using ClusterProfiler package. Statistical analysis was performed using GraphPad Prism 6.0. RESULTS: AICAr is capable of triggering differentiation in samples of bone marrow blasts cultured ex vivo that were resistant to ATRA. AICAr-induced differentiation correlates with proliferation and sensitivity to DHODH inhibition. RNA-seq data obtained in primary AML blasts confirmed that AICAr treatment induced downregulation of pyrimidine metabolism pathways together with an upregulation of gene set involved in hematopoietic cell lineage. CONCLUSION: AICAr induces differentiation in a subset of primary non-APL AML blasts, and these effects correlate with sensitivity to a well-known, potent DHODH inhibitor.

The Impact of Mother's Living Environment Exposure on Genome Damage, Immunological Status, and Sex Hormone Levels in Newborns.

Background: The aim of this study was to compare for the first time IL-6 (Interleukin 6), testosterone (T) and estradiol (E) levels, their ratio (E/T), micronucleus (MN), and nuclear bridge (NB) frequency between newborns with regard to their mother's residency and diet. Our results should enable an assessment of the possible environmental endocrine effects and interaction between biomarkers, pointing to possible associated health risks. Methods: Fifty full-term newborns of both sexes, whose mothers were healthy and not occupationally exposed to any known carcinogen, were analyzed. All of the mothers filled in a detailed questionnaire. Results: The results showed significantly higher levels of E in newborns of mothers with agricultural residency than those born by mothers with urban residency. Significantly, lower levels of E were measured in newborns of mothers who drank milk and carbonated beverages more frequently. Testosterone was significantly higher in boys of mothers with agricultural residency than from mothers with urban residency. Residence and other parameters had no impact on the difference in MN frequency. IL-6 levels were higher in newborns of mothers with agricultural residency. NB levels were significantly associated with E. A significant association between E levels and IL-6 was found. Conclusion: Our results were the first to show a significant impact of the mother's agricultural residency and diet on their newborns' sex hormone and IL-6 levels and their association.

Immunoglobulin heavy/light chain analysis enhances the detection of residual disease and monitoring of multiple myeloma patients.

AIM: To evaluate the clinical utility of incorporating a novel heavy/light chain immunoassay (HLC) into the existing methods for the assessment of multiple myeloma (MM) patients. METHODS: Convenience sera samples from 90 previously treated IgG and IgA MM patients in different disease stages were analyzed. The study was conducted in Clinical Hospital Center Zagreb between 2011 and 2013. The collected sera were analyzed by standard laboratory techniques (serum protein electrophoresis, quantification of total immunoglobulins, serum immunofixation, serum free light chain [FLC] assay) and HLC assay. RESULTS: HLC ratios outside the normal range were found in 58 of 90 patients, including 28 out of 61 patients with total immunoglobulin measurements within the normal range and 5 out of 23 patients in complete response. Both elevated HLC isotype level and abnormal HLC ratio correlated with the parameters of tumor burden, including percentage of plasma cells in the bone marrow (P<0.001 and P=0.002, respectively) and an abnormal serum FLC ratio (for both P<0.001). In addition, abnormal HLC isotype level correlated with serum beta-2-microglobulin level (P=0.038). In terms of prognosis, abnormal HLC isotype level and abnormal HLC ratio were significantly associated with shorter overall survival (P<0.001 and P=0.002, respectively). Interestingly, suppression of the uninvolved (polyclonal) isotype pair, but not other non-myeloma immunoglobulin isotypes, was also associated with a shorter overall survival (P=0.021). In a multivariate analysis, an abnormal HLC ratio and ß2-microglobulin level >3.5mg/L were independent risk factors for survival. CONCLUSION: The new HLC assay has greater sensitivity in detecting monoclonal protein, correlates with tumor burden markers, and affects patients' outcome.

Prognostic significance of constitutive phosphatidylinositol 3-kinase/Akt and mitogen-activated protein kinase phosphorylation in acute myeloid leukemia.

Acute myeloid leukemia (AML) is a malignant hematopoietic disease with poor clinical course and outcome. There is a constant need for new prognostic factors that could facilitate patient risk stratification. The aim of our research was to determine the phosphorylation levels of phosphatidylinositol 3-kinase (PI3K)/Akt and mitogen-activated protein kinase (MAPK) pathways in leukemic cells, their relation to P-glycoprotein (P-gp) expression/activity and their prognostic significance in adult de novo AML. A total of 118 patients with AML were enrolled in the study. In a multivariate Cox regression analysis we found that P-gp activity and Akt phosphorylation were independent poor prognostic factors of overall survival (OS). In contrast, phosphorylated extracellular signal-regulated kinase 1/2 (ERK1/2) represented a favorable prognostic factor of OS and relapse-free survival (RFS). A negative correlation between P-gp activity and p38 phosphorylation level was found, implying a possible role of this MAPK pathway in P-gp regulation. In addition, we found correlation between Akt and p38 phosphorylation levels, indicative of co-activation of two signaling cascades in AML.

Multiparameter flow cytometry is necessary for detection, characterization and diagnostics of composite mature B-cell lymphoproliferative neoplasms.

Composite mature B-cell lymphoproliferative neoplasms are rare entities characterized by the simultaneous presence of two or more distinctive B-cell derived monoclonal malignancies. This retrospective study used multiparametric flow cytometric analysis aimed at immunophenotypic profiling of composite mature B-cell lymphoproliferative neoplasms in a cohort of 413 subsequent patients with de novo leukemic B-cell chronic lymphoproliferative disorders diagnosed in our institution during a 30-month period. Biclonality was found in 16 (3.9 %) patients. The vast majority (88 %) of the cases had one of the clones phenotypically corresponding to chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL). Only when composite cases were categorized by phenotype of the non-CLL/SLL malignant population did we find a statistically significant (P = 0.001) higher frequency of biclonality among cases with hairy cell leukemia (22 %). Biclonal cases had the overall B-cell membrane κ to λ ratio within the normal range (median, 1.9; reference interval 0.5-4.0), making recognition of malignancy somewhat challenging. Our analysis strategy was therefore based on the detection of aberrant B-cell phenotypes, with subsequent confirmation of the monoclonal nature of neoplastic clones with regards to light chain restriction analysis. Discrimination of the coexisting clones in biclonal cases was possible on the basis of the expression of other antigen(s) (63 %), light scatter properties (44 %), different surface light chain restriction (69 %) and/or pattern of expression (44 %). The most informative cell surface antigens proved to be CD22, CD20, surface IgM, and CD23. In conclusion, historic κ/λ ratio is not a reliable approach and is a poor measurement for the detection of composite lymphomas. More creative analysis techniques should be utilized for this purpose.

[Extracorporeal photopheresis in treatment of chronic graft versus host disease]. / Ekstrakorporalna fotofereza u lijecenju kronicne reakcije transplantata protiv primatelja.

Extracorporeal photopheresis (ECP) is an immunomodulatory therapy which has been used in the treatment of chronic GVHD (cGVHD). ECP involves separation of the mononuclear cells with leukapheresis, followed by ex vivo administration of 8-methoxypsoralen and UV-A radiation and reinfusion to the patient. Aim of the study was to evaluate clinical and immunomodulatory effect of ECP procedures in patients with cGVHD. We analyzed 341 ECP procedures performed in 7 patients with cGVHD; median ECP per patient was 37 (range 13-131). All patients suffered from skin changes in combination with impaired joint mobility and symptoms of oral disease. ECP procedures were performed for two consecutive days: in initial phase weekly, followed by every two weeks and than monthly according to clinical response. Median of ECP treatment duration was 10 months (range 2-58). The effect of ECP in patients with cGVHD with skin andjoint involvement was mostly beneficial: 6 patients experienced either improvement or stabilization in skin changes and joint mobility. In 2 patients who suffered from oral disease, the total recovery was observed. Clinical response was typically delayed until 2 to 3 months, and reduction in glucocorticoid dose was observed. Adverse reactions were observed in 4.9% procedures. In patients who responded to ECP treatment, CD4+/CD8+ ratio and number of NK cells were normalized. ECP proved to be an efficient and safe procedure that may be recommended for patients with cGVHD who do not respond to conventional therapy.

ZAP-70 expression and proliferative activity in chronic lymphocytic leukemia.

The expression of 70 kDa protein zeta-associated protein (ZAP-70) in chronic lymphocytic leukemia (CLL) has been used to detect those patients with more aggressive disease. The aim of this study was to determine the proliferative activity of ZAP-70(+) leukemic cells by immunocytochemical methods. The study was undertaken on native blood marrow (BM) and peripheral blood (PB) smears from 65 patients with CLL. ZAP-70 was expressed in leukemic cells of 35 patients (54%). We demonstrated that ZAP-70 immunoreactivity correlated with Rai 0-IV (p = 0.002) and Binet A-C stages (p < 0.001), total tumor mass (TTM score) (p < 0.001), ß2-microglobulin (p = 0.006), atypical lymphocytes (p < 0.001) and proliferative activity in bone marrow and peripheral blood (p = 0.014, p = 0.002, respectively) using χ(2) test and Mann-Whitney test. ZAP-70 protein expression is in direct correlation with the poorer prognostic parameters, which additionally confirms the successful method of detection of ZAP-70 expression. Higher Ki-67 expression in BM and PB smears of patients with ZAP-70(+) disease indicates higher proliferating compartments, which may contribute to poorer prognosis.

Carboplatin resistant human laryngeal carcinoma cells are cross resistant to curcumin due to reduced curcumin accumulation.

Curcumin is a natural compound that exhibits a wide range of beneficial effects, among them the anti-tumor activity. Recently it was shown that curcumin may be efficient against drug resistant tumor cells. The goal of our investigation was to examine if human laryngeal carcinoma cells resistant to carboplatin display sensitivity to curcumin, as compared to parental cells, and if this sensitivity is altered, to determine the molecular mechanisms that are responsible for it. We found that carboplatin resistant 7T cells were also cross resistant to curcumin. After the treatment with equimolar concentration of curcumin, 7T cells exhibited lower intracellular accumulation of curcumin which coincided with reduced formation of reactive oxygen species (ROS), diminished lipid and DNA damage followed by reduced induction of apoptosis and expression of heat shock protein 70 (Hsp70), as compared to parental HEp-2 cells. However, after the treatment with equitoxic concentration of curcumin, intracellular accumulation and all the explored downstream effects were similar in both cell lines suggesting that resistance of 7T cells to curcumin was based on its reduced intracellular accumulation. Since curcumin accumulates mostly in the membranes, we explored the fatty acid composition of both cell lines, but we did not find any difference between them.

Epstein-Barr virus-negative aggressive natural killer-cell leukaemia with high P-glycoprotein activity and phosphorylated extracellular signal-regulated protein kinases 1 and 2.

Aggressive natural killer-cell leukaemia (ANKL) is a rare type of disease with fulminant course and poor outcome. The disease is more prevalent among Asians than in other ethnic groups and shows strong association with Epstein-Barr virus (EBV) and P-glycoprotein (P-gp) expression associated with multidrug resistance. Here we present a case of a 47 year old Caucasian female with a prior medical history of azathioprine treated ulcerative colitis who developed EBV-negative form of ANKL. The patient presented with hepatosplenomegaly, fever and nausea with peripheral blood and bone marrow infiltration with up to 70% of atypical lymphoid cells positive for cCD3, CD2, CD7, CD56, CD38, CD45, TIA1 and granzyme B, and negative for sCD3, CD4, CD5, CD8, CD34 and CD123 indicative of ANKL. Neoplastic CD56(+) NK-cells showed high level of P-glycoprotein expression and activity, but also strong expression of phosphorylated extracellular signal-regulated protein kinases 1 and 2 (ERK1/2) MAP kinase. The patient was treated with an intensive polychemotherapy regimen designed for treatment of acute lymphoblastic leukaemia, but one month after admission developed sepsis, coma and died of cardiorespiratory arrest. We present additional evidence that, except for the immunophenotype, leukaemic NK-cells resemble normal NK-cells in terms of P-gp functional capacity and expression of phosphorylated ERK1/2 signalling molecule. In that sense drugs that block P-glycoprotein activity and activated signalling pathways might represent new means for targeted therapy.

Large volume leukapheresis: Efficacy and safety of processing patient's total blood volume six times.

Large-volume leukapheresis (LVL) differs from standard leukapheresis by increased blood flow and an altered anticoagulation regimen. An open issue is to what degree a further increase in processed blood volume is reasonable in terms of higher yields and safety. In 30 LVL performed in patients with hematologic malignancies, 6 total blood volumes were processed. LVL resulted in a higher CD34+ cell yield without a change in graft quality. Although a marked platelet decrease can be expected, LVL is safe and can be recommended as the standard procedure for patients who mobilize low numbers of CD34+ cells and when high number of CD34+ cells are required.

Rhabdomyosarcoma with bone marrow infiltration mimicking hematologic neoplasia.

Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in children younger than 15 years. According to the World Health Organization, there are embryonal, alveolar and pleomorphic types of RMS. Most RMS patients present with a tumor mass in the head and neck region, urogenital tract or lower extremities. Unusual clinical presentation of the disease with massive bone marrow infiltration at the disease onset and mimicking hematologic neoplasm is rarely seen. A case is presented of a 14-year-old, previously healthy girl hospitalized for outpatiently detected leukocyte elevation. For the last two weeks, she had complained of fatigue, myalgia and frequent bruising. On admission, clinical examination revealed numerous petechiae and hematomas, enlarged left inguinal lymph node and palpable spleen 2 cm below left costal arch. Laboratory findings showed leukocytosis, anemia and thrombocytopenia. Bone marrow fine needle aspiration (FNA) produced a hypercellular bone marrow sample with suppression of all three hemocytopoiesis lines and bone marrow infiltration with numerous undifferentiated tumor cells. Considering the morphological, cytochemical and phenotypic characteristics, the cytologic diagnosis was: bone marrow infiltration with RMS cells. Abdominal computerized tomography revealed a primary tumor occupying the entire retropeoritoneal space. Tumor biopsy confirmed alveolar subtype of RMS. In conclusion, in cases of bone marrow infiltration with primitive, immature cells, RMS should be considered as differential diagnostic possibility. Adjuvant technologies (cytochemistry, immunocytochemistry, cytogenetic analysis, flow cytometry, and molecular analysis) can be very helpful in diagnostic work-up, and may lead to definitive diagnosis in some cases.

Collection and composition of autologous peripheral blood stem cells graft in patients with acute myeloid leukemia: influence on hematopoietic recovery and outcome.

Hematopoietic stem cell (HSC) transplantation is a standard approach in the treatment of hematological malignant diseases. For the last 15 years the main source of cells for transplantation have been peripheral blood stem cells (PBSC). With the availability of hematopoietic growth factors and understanding the advantages of treatment with PBSC, the application of bone marrow (BM) was supplanted. The aim of this survey was to explore the success of PBSC collection, the factors which influence the success of PBSC collection, the composition and the quality of graft and their influence on hematopoietic recovery and outcome after transplantation in patients with acute myeloid leukemia (AML). PBSC were collected by the method of leukapheresis after applying a combination of chemotherapy and growth factors or only growth factors. The quality of graft was determined with the clonogenic progenitor cell assay and with the flow cytometry analysis. Of the total 134 patients with AML, who were submitted to HSC mobilization, the collection was successful in 78 (58.2%) patients. The collection was more successful after the first than after the second attempt of HSC mobilization (49% vs. 11%). The criteria for effective mobilization were the number of leukocytes > 3 x 10(9)/L and the concentration of CD34+ cells > 20 x 10(3)/mL in the peripheral blood on the first day of leukapheresis. The number of CD34+ cells infused had the strongest impact on hematopoietic recovery. We noted significantly faster hematological recovery of neutrophils and platelets, fewer number of transfused units of red blood cells and platelets, shorter duration of the tranfusion support, shorter treatment with intravenous antibiotic therapy and shorter hospitalization after PBSC compared to BM transplantation. These advantages could provide their standard application in the treatment of patients with AML.