Rate of tuberculosis infection in children and adolescents with household contact with adults with active pulmonary tuberculosis as assessed by tuberculin skin test and interferon-gamma release assays.

Tuberculosis (TB) infection was evaluated in Brazilian immunocompetent children and adolescents exposed and unexposed (control group) to adults with active pulmonary TB. Both groups were analysed by clinical and radiological assessment, TST, QFT-IT and T-SPOT.TB. The three tests were repeated after 8 weeks in the TB-exposed group if results were initially negative. Individuals with latent tuberculosis infection (LTBI) were treated and tests were repeated after treatment. Fifty-nine TB-exposed and 42 controls were evaluated. Rate of infection was 69·5% and 9·5% for the exposed and control groups, respectively. The exposed group infection rate was 61% assessed by TST, 57·6% by T-SPOT.TB, and 59·3%, by QFT-IT. No active TB was diagnosed. Agreement between the three tests was 83·1% and 92·8% in the exposed and control groups, respectively. In the exposed group, T-SPOT.TB added four TB diagnoses [16%, 95% confidence interval (CI) 1·6-30·4] and QFT-IT added three TB diagnoses (12%, 95% CI 0-24·7) in 25 individuals with negative tuberculin skin test (TST). Risk factors associated to TB infection were contact with an adult with active TB [0-60 days: odds ratio (OR) 6·9; >60 days: OR 27·0] and sleeping in the same room as an adult with active TB (OR 5·2). In Brazilian immunocompetent children and adolescents, TST had a similar performance to interferon-gamma release assays and detected a high rate of LTBI.

Cardiovascular manifestations of Erdheim-Chester disease.

Erdheim-Chester disease (ECD) is a rare inflammatory disorder of unknown etiology, characterised by diffuse organ infiltration of CD68-positive, CD1a-negative, S100-low/negative foamy histiocytes. It is a non-Langerhans cell histiocytosis which invariably involves bones (96% of cases). Extraskeletal involvement is observed in about 50% of cases. Cardiovascular involvement affects more than 20% of patients and associates with poor prognosis, conferring a reduced response to treatment. Frequent findings are pericardial effusion (24% of patients), "coated aorta", a perivascular circumferential thickening of the aorta, and pericardial thickening. Other typical features include right atrial mass with pseudo-tumoural appearance and histiocytes' infiltration of right atrial walls, atrioventricular sulcus and interatrial septum. After the recent introduction of cardiac cine MRI in the clinical assessment of patients affected by ECD, a growing body of case reports and retrospective data showed that cardiovascular involvement is present more frequently than previously thought and that it is relatively often asymptomatic. Hence, clinicians should systematically screen ECD patients for occult cardiovascular involvement by means of highly sensitive imaging tools. Despite these recent novelties, comprehensive literature reviews focusing on ECD cardiovascular involvement and its imaging assessment in the last decade are lacking.

Second-line treatment with intravenous gemcitabine and oral etoposide in platinum-resistant advanced ovarian cancer patients: results of a phase II study.

OBJECTIVE: The outcome of advanced ovarian cancer patients has not significantly improved since the introduction of platinum. One of the major reasons for this failure is the lack of an effective second-line treatment. In this phase II trial we tested the combination of gemcitabine and etoposide in 2 different groups of patients. Group 1 consisted of patients showing disease progression or relapse within 6 months of first-line platinum-based chemotherapy. Group 2 comprised heavily pretreated patients showing progression during the last chemotherapy attempt. METHODS: Thirty-four patients were enrolled. Gemcitabine was administered at a dose of 1,000 mg/m(2) on days 1 and 8 and etoposide was administered orally at 100 mg/day on days 8-12 for 6 courses. RESULTS: Eighteen patients (52.9%) had an objective response and the median duration of the response was 10.3 months. Our chemotherapy regimen showed a low toxicity and good patient compliance. In 5 patients the treatment had to be delayed and in only 2 patients it was discontinued. CONCLUSIONS: The combination of gemcitabine and oral etoposide seems to be a safe and effective second-line treatment for platinum-resistant ovarian cancer patients. Additional data on larger series are warranted to better define the activity of this combination regimen.

Apoptotic cells overexpress vinculin and induce vinculin-specific cytotoxic T-cell cross-priming.

Here we show that apoptotic cells overexpress vinculin and are ingested by dendritic cells, which subsequently cross-prime vinculin-specific cytotoxic T lymphocytes (CTLs). Successful cross-priming requires that the apoptotic cells provide maturation signals to dendritic cells through CD40-CD40 ligand (CD40L) interactions. If apoptotic cells are CD40L-, the help of a third T cell is needed for priming, indicating a regulatory role for apoptotic cells in determining priming or tolerance. Vinculin-specific CTL priming is also related to apoptosis in vivo, given that in HIV-seropositive individuals, the frequency of specific CTLs depends on the proportion of peripheral CD40L+ apoptotic cells.

Transfection of the c-myc oncogene into normal Epstein-Barr virus-harboring B cells results in new phenotypic and functional features resembling those of Burkitt lymphoma cells and normal centroblasts.

Activated c-myc gene was introduced into the cells of three normal Epstein-Barr virus (EBV)-positive lymphoblastoid B cell lines (LCL). The cells were monitored for the appearance of new phenotypic and functional features compared with the control LCL cells transfected with plasmid that did not contain the c-myc gene. The LCL-expressing c-myc constitutively did not arrest growth in low serum concentration. However, the cell number in the cultures failed to increase because of substantial cell death. Death was due to apoptosis as demonstrated by flow cytometric analysis of propidium iodide-stained cells, by typical DNA laddering in gel electrophoresis, and by the inspection of Giemsa-stained cell smears. Apoptosis was also induced by exposing the transfected cells to antibodies directed to the immunoglobulin mu chain (a-mu-ab) irrespective of the serum concentration in the culture. Exposure of the cells to CD40 ligand (CD40L) or CD40 monoclonal antibody prevented cell apoptosis. Upon transfection with c-myc, the LCL cells acquired a vacuolated morphology that was never observed in control cells. Moreover, the expression of CD10 and CD38 was upregulated, while that of CD39 and especially CD23 was downregulated. Unlike that observed in certain Burkitt lymphoma (BL) cell lines that share the same surface phenotype (CD10+CD38+CD23-CD39-), the c-myc-transfected cells expressed lymphocyte function-associated (LFA) 1, LFA-3, and intercellular adhesion molecule 1 and grew in large clumps rather than single-cell layers. Expression of CD10 and CD38 was particularly evident on the cells undergoing apoptosis, thus suggesting a correlation between the presence of these markers and the apoptotic process. Cells placed in conditions favoring in vitro apoptosis displayed downregulation of Bcl-2 protein. Bcl-2 expression was, however, upregulated when the cells were exposed to CD40L. These data indicate that the B cells expressing c-myc constitutively acquire some of the features of normal centroblasts and of BL cells, including the expression of CD10 and CD38, and the propensity to undergo apoptosis, which can be prevented by exposure to CD40L. Therefore, these cells can serve as a model system to study both BL lymphomagenesis as well as the process of B cell selection occurring in the germinal centers.

Characterization of cells from invaded lymph nodes in patients with solid tumors. Lymphokine requirement for tumor-specific lymphoproliferative response.

The specific immune response against the malignant cells was investigated in patients with urinary bladder or larynx cancer. Lymphocytes from lymph nodes that drain the tumor site were tested for their proliferative and cytotoxic capacities against autologous malignant cells isolated from the primary tumor. In no occasion was a proliferative or a cytotoxic response observed. However, when the lymph node cell suspensions were depleted of cells expressing both OKM1 and Leu-7 markers by rosetting with the appropriate mAbs, a proliferative response could be observed. The lymphocytes responded to autologous tumor cells only if IL-2 was added to the cultures. IL-2 alone induced some cell proliferation, which was not, however, comparable to that observed in response to both IL-2 and tumor cells. A panel of allogeneic tumor cells consistently failed to stimulate OKM1-, Leu-7- cells in vitro. Response to autologous tumor cells was not caused by HLA-encoded molecules, as occurs in the autologous mixed lymphocyte reaction, since OKM1-, Leu-7- cells failed to be stimulated by autologous non-T cells. A proliferative response was observed only with cells from lymph nodes that had been classified as invaded by malignant cells according to histopathologic criteria. Cells from noninvaded lymph nodes consistently failed to respond. Cells stimulated with autologous tumor cells could be expanded in short-term lines by continuous addition of IL-2 and malignant cells. One of these lines, which comprised mainly T8+ cells, was stimulated to proliferate only by autologous tumor cells, and its proliferative response was inhibitable by anti-class I and not by anti-class II mAbs. This line showed lytic capacities against autologous malignant targets, while it was inefficient against all of the other allogeneic cells tested. In another set of experiments, the mechanisms whereby exogenous IL-2 had to be added to the cultures to sustain a proliferative response against neoplastic cells were investigated. When cocultured with autologous malignant cells, OKM1-, Leu-7- lymphocytes expressed IL-2 receptors, as could be assessed by anti-Tac fluorescent staining. Under these culture conditions, these cells did not produce IL-2, and no proliferation was observed. Addition of purified IL-1 to the cultures induced IL-2 production and cell proliferation. It is concluded that metastatic lymph nodes contain a T cell population that can be detected in a proliferative assay when both suppressor cells are removed and the appropriate molecular signals are supplied.

Somatic diversification and selection of immunoglobulin heavy and light chain variable region genes in IgG+ CD5+ chronic lymphocytic leukemia B cells.

Chronic lymphocytic leukemia (CLL) is characterized by the clonal expansion of CD5-expressing B lymphocytes. Most studies have found that these leukemic CD5+ B cells, like their normal counterparts, use immunoglobulin (Ig) variable (V) region genes that exhibit minimal, if any, somatic diversity. These and other observations have suggested that CD5+ B cells may be incapable of generating Ig V gene diversity, and therefore may not be able to develop higher affinity binding sites that could be selected by antigen. However, most of the studies of CLL and normal CD5+ B cells have focused on IgM-producing cells. Since somatic mutations are most often seen in B cells that have undergone an isotype class switch, we analyzed the Ig heavy (H) and light (L) chain variable region genes of seven IgG+CD5+ CLL B cells to determine if somatic diversification and antigen selection had occurred. The data derived provide evidence for skewed use, somatic diversification, and antigenic selection of the Ig V region genes. Nonrandom use of both H and L chain V region genes was manifested by an overrepresentation of VH4 and VKI family genes and the underrepresentation of the JH4 gene segment. Furthermore, VH4 gene use was restricted to only two family members (4.21 and 4.18). In four of the seven cases, the VH and VL genes displayed > or = 5% difference from the most homologous known germline counterparts. Polymerase chain reaction and Southern blot analyses performed in two of these patients demonstrated that their unique VH CDR2 and adjacent sequences were not present in their germline DNA. In addition, a significant level of diversity was seen in the rearranged DJH segments and at the VL-JL junctions of every patient that occurred both at the time of recombination and subsequently. The localization of replacement changes to complementarity determining regions of some patients suggested that antigen selection had occurred. Furthermore, the mutations identified in the VH and VL genes of each individual patient were strikingly similar, both in number and location. Collectively, the data indicate that a subset of CD5+ CLL B cells can display Ig V region gene mutations. In addition, they are consistent with the notions that in some cases antigen selection of these mutations may have occurred, and that antigen stimulation may be a promoting factor in the evolution of certain CLL clones.

Seipin S90L mutation in an Italian family with CMT2/dHMN and pyramidal signs.

Heterozygous mutations in the Berardinelli-Seip congenital lipodystrophy (BSCL2) gene have been associated with different clinical phenotypes including Silver syndrome/spastic paraplegia 17, distal hereditary motor neuropathy type V, and Charcot-Marie-Tooth disease type 2 (CMT2) with predominant hand involvement. We studied an Italian family with a CMT2 phenotype with pyramidal signs that had subclinical sensory involvement on sural nerve biopsy. Direct sequencing analysis of the BSCL2 gene in the three affected siblings revealed an S90L mutation. This report confirms the variability of clinical phenotypes associated with a BSCL2 Ser90Leu mutation and describes the first Italian family with this mutation.

Evaluation of blockbuster drugs under the rule-of-five.

The current drug research techniques, combinatorial synthesis and high throughput screening, enabled the obtaining and pre-evaluation of thousands of compounds in short time. In order to chose the best hits to become leads, observation of drug-likeness tries to optimize this selection. Probably, the most widely used filter is Lipinski's Rule-of-five, which proposes that molecules with poor permeation and oral absorption have molecular weight > 500, Clog P > 5, hydrogen-bond donor > 5 and hydrogen-bond acceptor > 10. In order to evaluate the Rule-of-five, the top pharmaceutical products in 2007 were analyzed. Among 60 drugs, 7 (atorvastatin, montelukast, docetaxel, telmisartan, tacrolimus, leuprolide and olmesartan) did not fit the rule, and 5 failed only one of the threshold values. It was possible to conclude that the rule is very useful to select better compounds in chemolibraries, but it must be used carefully and with criteria, to avoid a possible exclusion of promising compounds.

Angular distribution of neutron production by proton and carbon-ion therapeutic beams.

Carbon-ion beams are increasingly used in the clinical practice for external radiotherapy treatments of deep-seated tumors. At therapeutic energies, carbon ions yield significant secondary products, including neutrons, which may be of concern for the radiation protection of the patient and personnel. We simulated the neutron yield produced by proton and carbon-ion pencil beams impinging on a clinical phantom at three different angles: 15°, 45° and 90°, with respect to the beam axis. We validated the simulated results using the measured response of organic scintillation detectors. We compared the results obtained with FLUKA 2011.2 and MCNPX 2.7.0 based on three different physics models: Bertini, Isabel, and CEM. Over the different ions, energies, and angles, the FLUKA simulation results agree better with the measured data, compared to the MCNPX results. Simulations of carbon ions at low angles exhibit both the highest deviation from measured data and inter-model discrepancy, which is probably due to the different treatment of the pre-equilibrium stage. The reported neutron yield results could help in the comparison of carbon-ion and proton treatments in terms of secondary neutron production for radiation protection applications.

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leucoencephalopathy and right-to-left shunt: lack of evidence for an association in a prevalence study.

BACKGROUND/AIMS: Up to more than 50% of cryptogenetic stroke patients and patients with migraine with aura (MA) are found to have a right-to-left shunt (RLS), which is usually due to a patent foramen ovale. Moreover, both MA and stroke are cardinal features of cerebral autosomal dominant arteriopathy with subcortical infarcts and leucoencephalopathy (CADASIL). Notch3 mutations have been suggested to induce an abnormally high incidence of atrial septal defects in a family harbouring an Arg141Cys pathogenetic mutation. We sought to determine the prevalence of RLS in CADASIL patients with different Notch3 mutations, both with and without migraine as a clinical feature. METHODS: Subjects with a molecular diagnosis of CADASIL were tested for the presence of an RLS by means of contrast-enhanced transcranial Doppler (TCD). The diagnosis of migraine was made according to the 2004 International Headache Classification. RESULTS: Sixteen CADASIL patients were tested; 6 had MA. Four patients displayed an RLS on contrast-enhanced TCD examination. Three of these patients had MA. Both patients with Arg141Cys displayed a large RLS. CONCLUSION: We conclude that RLS is not necessarily linked to CADASIL as a comorbidity factor. Nevertheless, there could be a relation between RLS and specific Notch3 mutations, such as Arg141Cys.

Contribution of the interferon-gamma release assay to tuberculosis diagnosis in children and adolescents.

SETTING: As conclusive data on the performance of interferon-gamma release assays (IGRAs) in paediatric TB are lacking, many guidelines do not recommend their use for TB diagnosis in this population in Brazil. OBJECTIVE: To evaluate the performance of an IGRA by investigating its concordance with the tuberculin skin test (TST) and the role of IGRAs in clinical management and treatment outcomes in children with TB. DESIGN: A historic cohort study was used to evaluate the performance of T-SPOT®.TB (ELISpot) and other tests, such as the TST, in paediatric patients with or without immunodeficiency who were under investigation for latent tuberculous infection (LTBI) or active tuberculosis (TB). RESULTS: Of 86 paediatric patients evaluated, 41 (48%) were immunocompetent and 45 (52%) immunocompromised. All patients underwent T-SPOT.TB, while 63 underwent both ELISpot and TST; test results were concordant in 50 patients (79.4%): 22/31 (71%) in immunocompetent (κ = 0.418, P = 0.02) and 28/32 (87.5%) in immunocompromised patients (κ = 0.526, P = 0.003). TB was diagnosed on the basis of the ELISpot result in 21% (18/86) cases; the contribution of the ELISpot assay was greater in immunocompetent patients than in those who were immunocompromised (13/41, 31.7% vs. 5/45, 11.1%, χ2 P = 0.038). CONCLUSION: ELISpot and TST results were moderately concordant in both groups of patients. ELISpot contribution was higher among immunocompetent patients than among immunocompromised patients.

Chronic lymphocytic leukemia B cells express restricted sets of mutated and unmutated antigen receptors.

To better understand the stage(s) of differentiation reached by B-type chronic lymphocytic leukemia (B-CLL) cells and to gain insight into the potential role of antigenic stimulation in the development and diversification of these cells, we analyzed the rearranged VH genes expressed by 83 B-CLL cells (64 IgM+ and 19 non-IgM+). Our results confirm and extend the observations of a bias in the use of certain VH, D, and JH genes among B-CLL cells. In addition, they indicate that the VH genes of approximately 50% of the IgM+ B-CLL cells and approximately 75% of the non-IgM+ B-CLL cells can exhibit somatic mutations. The presence of mutation varies according to the VH family expressed by the B-CLL cell (VH3 expressers displaying more mutation than VH1 and VH4 expressers). In addition, the extent of mutation can be sizeable with approximately 32% of the IgM+ cases and approximately 68% of the non-IgM+ cases differing by > 5% from the most similar germline gene. Approximately 20% of the mutated VH genes display replacement mutations in a pattern consistent with antigen selection. However, CDR3 characteristics (D and JH gene use and association and HCDR3 length, composition, and charge) suggest that selection for distinct B cell receptors (BCR) occurs in many more B-CLL cells. Based on these data, we suggest three prototypic BCR, representing the VH genes most frequently encountered in our study. These data suggest that many B-CLL cells have been previously stimulated, placing them in the "experienced" or "memory" CD5(+) B cell subset.

Examples of in vivo isotype class switching in IgM+ chronic lymphocytic leukemia B cells.

Chronic lymphocytic leukemia (CLL) usually involves the expansion of a clone of CD5+ B cells synthesizing IgM antibodies. These B cells appear to be blocked at the antigen receptor-expressing stage of B cell differentiation and are thought not to undergo an isotype class switch to IgG or IgA production. In vivo and in vitro studies suggest, however, that in some instances terminal differentiation and isotype switching can occur. To test the hypothesis that in vivo isotype class switching occurs in IgM+ B-type CLL cells, we analyzed the PBMC of 19 CLL patients for the presence of transcripts encoding the rearranged CLL V(H)DJ(H) associated with either gamma or alpha H chains. The molecular data indicate that approximately 50% of B-CLL patients have amplifications of IgM+ B cells that undergo an isotype class switch. Switching to IgA appears to occur more often than to IgG; also, switching can involve different IgG subclasses in individual patients. In many instances, these CLL-related gamma and alpha transcripts are much more plentiful than those of normal B cells that produce the same isotype. These switched transcripts do not reveal evidence for the accumulation of significant numbers of new V(H) gene mutations. The cellular data indicate that B cells with lesser amounts of surface membrane IgD and higher IgM/IgD ratios are more likely to undergo this switching process. Furthermore, B cells expressing IgG and IgA of the same idiotype or V(H) family and the same CDR3 length as those of the CLL IgM+ clone can be identified in the blood of patients studied using multiparameter immunofluorescence analyses. Collectively, these data suggest that not all members of a B-CLL clone are frozen at the surface membrane Ig-expressing stage of B cell maturation, and that some members can switch to the production of non-IgM isotypes. The occurrence of switching without the accumulation of V gene mutations indicates that the processes of differentiation and diversification are not linked.

Inhibition of Burkitt's lymphoma cells growth in SCID mice by a PNA specific for a regulatory sequence of the translocated c-myc.

In Burkitt's lymphoma (BL) cells due to a t(8;14) chromosomal translocation c-myc is often placed in proximity to the Emu enhancer of the Ig locus and upregulated. We demonstrated that in BL cells a peptide nucleic acid (PNA), complementary to intronic Emu sequences (PNAEmuwt), specifically blocks the expression of the c-myc oncogene under the Emu enhancer control and inhibits BL cell growth in culture. Here, we investigated whether PNAEmuwt was also able to block tumor growth in SCID mice inoculated with human BL cell lines. After subcutaneous inoculum in mice BL cells reproducibly form tumors. Both pre-treatment of BL cells with PNAEmuwt before inoculum and chronic intravenous administration of PNAEmuwt to mice already inoculated with BL cells selectively caused increased latency of tumor appearance and decreased final tumor size. Tumors from PNAEmuwt-treated animals showed substantial areas of cell necrosis and of c-myc downregulation. Inhibition of tumor growth was specific and was not observed with PNAEmumut carrying sequence mutations and in BL cell lines where the translocated c-myc is not under the control of the Emu enhancer. These data confirm the potential therapeutic value of PNA targeted to regulatory non-coding regions.

Lack of mutagenicity and clastogenicity of PNAEmu-NLS targeted to a regulatory sequence of the translocated c-myc oncogene in Burkitt's lymphoma.

Peptide nucleic acids (PNAs) are synthetic homolog of nucleic acids in which the phosphate-sugar polynucleotide backbone is replaced by a flexible polyamide. They bind complementary polynucleotide sequences with higher affinity and specificity than their natural counterparts. PNAs linked to the appropriate nuclear localization signal (NLS) peptide have been used to selectively down-regulate the expression of several genes in viable cells. For example in Burkitt's lymphoma (BL) cells the c-myc oncogene is translocated in proximity to the Emu enhancer of the Ig gene locus and upregulated. PNAs complementary to the second exon of c-myc or to the Emu enhancer sequence (PNAEmu-NLS), selectively and specifically block the expression of the c-myc oncogene and inhibit cell growth in vitro and in vivo. PNAEmu-NLS administration to mice did not exhibit toxic effects even at the highest concentration allowed by the experimental conditions. Because of the accumulating data confirming PNAEmu-NLS potential therapeutic value, PNAEmu-NLS was evaluated for the inability to induce mutations in tester strains of Salmonella typhimurium, Escherichia coli, and at the hprt locus in Chinese hamster ovary cells (CHO). Moreover, the induction of chromosomal aberrations in CHO cells and of micronuclei in human lymphocytes were investigated. We may conclude that PNAEmu-NLS neither induces mutations nor has clastogenic effects as detectable by treatment under the standard test conditions.

Effects in live cells of a c-myc anti-gene PNA linked to a nuclear localization signal.

Peptide nucleic acids (PNA) are synthetic homologs of nucleic acids in which the phosphate-sugar polynucleotide backbone is replaced by a flexible polyamide. In this study, a PNA construct was employed as an anti-gene agent in intact cells in culture. The cell lines studied were derived from Burkitt's lymphomas (BL) that presented a translocated and hyperexpressed c-myc oncogene. A 17-mer anti-myc PNA, complementary to a unique sequence located at the beginning of the second exon of the oncogene, and was covalently linked at its N terminus to a nuclear localization signal (NLS) (PNA-myc(wt)-NLS). When BL cells were exposed to PNA-myc(wt)-NLS, the anti-gene construct was localized predominantly in the cell nuclei and a rapid consequent downregulation of c-myc expression occurred. Under these conditions, both completion of a productive cell cycle and apoptosis were inhibited.

Sensitivity study of CR39 track detector in an extended range Bonner sphere spectrometer.

Bonner sphere spectrometers (BSS) are being used widely in neutron spectrometry since 1960. The response to neutrons of these moderating detectors spans over a broad energy range. This work discusses the measurement of the sensitivity of an extended range BSS hosting a CR39 nuclear track detector coupled to a boron converter. Two kinds of boron converters were tested, the first made by natural boron and a second one enriched in (10)B. The BSS response functions were calculated with Monte Carlo simulation using the MCNPX 2.4.0. and the FLUKA codes.

Effects of miRNA-15 and miRNA-16 expression replacement in chronic lymphocytic leukemia: implication for therapy.

Chronic lymphocytic leukemia (CLL) clones are characterized by loss of a critical region in 13q14.3, (del(13)(q14)) involving the microRNA (miRNA) cluster miR-15a and miR-16-1. We have investigated the effects of replacement of miR-15a and miR-16-1. CLL cells transfected with these miRNA mimics exhibited a decrease in cell viability in vitro and impaired capacity for engraftment and growth in NOD/Shi-scid,γcnull (NSG) mice. No synergistic effects were observed when the two miRNA mimics were combined. The phenomena were not restricted to CLL with the del(13)(q14) lesion. Similar effects induced by miRNA mimics were seen in cells with additional chromosomal abnormalities with the exception of certain CLL clones harboring TP53 alterations. Administration of miRNA mimics to NSG mice previously engrafted with CLL clones resulted in substantial tumor regression. CLL cell transfection with miR-15a and miR-16-1-specific inhibitors resulted in increased cell viability in vitro and in an enhanced capacity of the engrafted cells to grow in NSG mice generating larger splenic nodules. These data demonstrate that the strong control by miR-15a and miR-16-1 on CLL clonal expansion is exerted also at the level of full-blown leukemia and provide indications for a miRNA-based therapeutic strategy.