[Show abstract][Hide abstract] ABSTRACT: Although rarely, switches between lymphoid and myeloid lineages may occur during treatment of acute leukemias (AL). Correct diagnosis relies upon confirmation by immunophenotyping of the lineage conversion and certification that the same cytogenetic/molecular alterations remain despite the phenotypic changes. From a total of 1,482 AL pediatric patients, we report nine cases of lineage conversion (0.6%), seven from lymphoid (four Pro-B, two Pre-B, one Common) to myelo-monocytic, and two from myeloid (bilineal, with myeloid predominance) to Pro-B. Eight patients were infants. Switches were suggested by morphology and confirmed with a median of 15 days (range: 8 days-6 months) from initiation of therapy. Of note, in five cases switches occurred before day 15. Stability of the clonal abnormalities was assessed by cytogenetic, RT-PCR/Ig-TCR rearrangement studies in all patients. Abnormalities in 11q23/MLL gene were detected in seven cases. Treatment schedules were ALL (two pts), Interfant-99 (five pts) and AML (two pts) protocols. Despite changing chemotherapy according to the new lineage, all patients died. Our findings support the association of lineage switches with MLL gene alterations and the involvement of a common lymphoid B-myeloid precursor. New therapies should be designed to address these rare cases. Possible mechanisms implicated are discussed.
American Journal of Hematology 05/2012; 87(9):890-7. · 4.00 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Ik-Bα deficient patients have shown several immune phenotypes. A male Argentinian infant presented from 2 to 3 years of age persistent inflammatory symptoms with multifocal bone involvement and osteoarthritis, which resulted to be caused by BCG Mycobacterium bovis infection. The patient had hypergammaglobulinemia with absent response to polysaccharide and protein stimuli. Lymphocyte subpopulations showed naive phenotype. The oxidative response was normal. T-Cells Function showned abnormal T cell proliferation in response to mitogens and antigen stimulation. Impaired cellular responses to TIR ligands and to TNFR superfamily members agonists. Flow cytometry evaluation of IL12-IFNγ AXIS showed normal expression of IFN gamma and β1chain IL12 receptors, normal STAT1 & STAT 4 phosphorylation through IFNγ stimulation, but impaired upon IFNα stimulation. Sequencing of the patient’s Ik-B alpha gene revealed a heterozygous missense mutation in serine 32 of Ik-B alpha. We describe an autosomal-dominant form of EDA-ID associated to a heterozygous missense mutation at serine 32 of IKBα and disseminated BCG Mycobacterium bovis infection.
2012 Clinical Immunology Society Annual Meeting; 05/2012
[Show abstract][Hide abstract] ABSTRACT: This study tested the hypothesis that the IFN-γ R1 287-YVSLI-91 intracellular motif regulates its endocytosis. IFN-γ exerts its biological activities by interacting with a specific cell-surface RC composed of two IFN-γ R1 and two IFN-γ R2 chains. Following IFN-γ binding and along with the initiation of signal transduction, the ligand and IFN-γ R1 are internalized. Two major types of consensus-sorting signals are described in receptors, which are rapidly internalized from the plasma membrane to intracellular compartments: tyrosine-based and dileucine-based internalization motifs. Transfection of HEK 293 cells and IFN-γ R1-deficient fibroblasts with WT and site-directed, mutagenesis-generated mutant IFN-γ R1 expression vectors helped us to identify region IFN-γ R1 287-YVSLI-291 as the critical domain required for IFN-γ-induced IFN-γ R1 internalization and Y287 and LI290-291 as part of a common structure essential for receptor endocytosis and function. This new endocytosis motif, YxxLI, shares characteristics of tyrosine-based and dileucine-based internalization motifs and is highly conserved in IFN-γ Rs across species. The IFN-γ R1 270-LI-271 dileucine motif, previously thought to be involved in this receptor endocytosis, showed to be unnecessary for receptor endocytosis.
Journal of leukocyte biology 05/2012; 92(2):301-8. · 4.99 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The present study was performed to establish the prevalence of the recurrent fusion transcripts in Argentinean pediatric patients with acute lymphoblastic leukemia (ALL). A total of 380 newly diagnosed children (including 50 infants and 44 T-ALL) were screened by RT-PCR; the incidence of recurrent rearrangements was: ETV6-RUNX1, 12.9%; TCF3-PBX1, 5.0%; BCR-ABL1, 1.6%; and MLL rearrangements, 10.5%. STIL-TAL1 was detected in 22.7% of T-ALL cases. In B-ALL cases, the pEFS was significantly influenced by the presence of genetic alterations. RT-PCR studies improved patients' stratification and also the overall outcome of children treated in a pediatric hospital from a developing country.
Leukemia research 01/2012; 36(6):704-8. · 2.36 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Common variable immunodeficiency (CVID) is a heterogeneous syndrome characterized by impaired immunoglobulin production. Mutations in the gene encoding TACI (TNFRSF13B) were previously found to be associated with CVID. Previous studies have identified a variety of sequence variants in TACI where A181E and C104R were the most common, with variable frequencies in different ethnic populations. So far, no mutations were identified in the recently reported "TACI highly conserved" (THC) cytoplasmic domain, important for the induction of class switch recombination. Our study evaluated immunological and clinical data on a cohort of 28 Argentinean pediatric CVID patients and allowed the identification of two novel mutations in TNFRSF13B, including one, S231R, affecting the highly conserved THC domain. In contrast, none of the patients presented with A181E and C104R mutations.
Journal of Clinical Immunology 11/2011; 32(1):89-97. · 3.38 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Historically, t(1;19)(q23;p13.3) has been related to pre-B acute lymphoblastic leukemia (ALL) and associated with a poor prognosis. Current treatments have overcome this dismal outcome, but advantages in survival for the unbalanced group have been reported. We compared the outcome of balanced and unbalanced der(19)t(1;19) cases and also patients with t(1;19)/TCF3-PBX1 versus patients without this translocation, to assess its prognostic value. From January 1990 to December 2010, t(1;19)(q23;p13)/TCF3-PBX1 was detected in 48 cases. Patients were treated with Berlin-Frankfurt-Münster (BFM)-based protocols and classified into balanced (n = 17) and unbalanced (n = 23) groups. The probability of event-free survival (pEFS) (standard error) of patients with t(1;19)/TCF3-PBX1 was 85% (6%), for the unbalanced group 78% (10%), and 88% (8%) for the balanced. The pEFS of patients with t(1;19)/TCF3-PBX1 was significantly superior to that of patients without t(1;19)/TCF3-PBX1 (p-value <0.0001). Patients with t(1;19)/TCF3-PBX1 presented a good outcome with no differences between balanced and unbalanced subgroups. Thus, risk-adjustment therapy would not be necessary for cases with t(1;19)/TCF3-PBX1.
[Show abstract][Hide abstract] ABSTRACT: Interleukin-12 receptor β1 (IL-12Rβ1) deficiency is the most common form of Mendelian susceptibility to mycobacterial disease (MSMD). We undertook an international survey of 141 patients from 102 kindreds in 30 countries. Among 102 probands, the first infection occurred at a mean age of 2.4 years. In 78 patients, this infection was caused by Bacille Calmette-Guérin (BCG; n = 65), environmental mycobacteria (EM; also known as atypical or nontuberculous mycobacteria) (n = 9) or Mycobacterium tuberculosis (n = 4). Twenty-two of the remaining 24 probands initially presented with nontyphoidal, extraintestinal salmonellosis. Twenty of the 29 genetically affected sibs displayed clinical signs (69%); however 8 remained asymptomatic (27%). Nine nongenotyped sibs with symptoms died. Recurrent BCG infection was diagnosed in 15 cases, recurrent EM in 3 cases, recurrent salmonellosis in 22 patients. Ninety of the 132 symptomatic patients had infections with a single microorganism. Multiple infections were diagnosed in 40 cases, with combined mycobacteriosis and salmonellosis in 36 individuals. BCG disease strongly protected against subsequent EM disease (p = 0.00008). Various other infectious diseases occurred, albeit each rarely, yet candidiasis was reported in 33 of the patients (23%). Ninety-nine patients (70%) survived, with a mean age at last follow-up visit of 12.7 years ± 9.8 years (range, 0.5-46.4 yr). IL-12Rβ1 deficiency is characterized by childhood-onset mycobacteriosis and salmonellosis, rare recurrences of mycobacterial disease, and more frequent recurrence of salmonellosis. The condition has higher clinical penetrance, broader susceptibility to infections, and less favorable outcome than previously thought.
Medicine 11/2010; 89(6):381-402. · 4.35 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening disease with major diagnostic and therapeutic difficulties, basically comprising two different conditions: primary and secondary forms. Recent advances regarding molecular diagnosis may be useful to distinguish from one another, especially in sporadic cases starting in early infancy.
In this report, we evaluated three Argentinean patients with clinical suspicion of HLH, but without family history. We excluded mutations in the perforin gene but identified in the three patients a novel homozygous deletion (c. 581_584delTGCC; p.Leu194ProfsX2) in the gene-encoding syntaxin 11 (STX11), causing a premature termination codon.
Each parent from the three unrelated families resulted heterozygous for this deletion confirming the diagnosis of familial hemophagocytic lymphohistiocytosis type 4. Patients shared the same single-nucleotide polymorphism profile in STX11 gene, and genotyping at ten microsatellites surrounding this gene support the presence of a single-haplotype block carrying the novel mutation.
Journal of Clinical Immunology 12/2009; 30(2):330-7. · 3.38 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Mutations in IFNGR1, IFNGR2, IL12RB1, IL12B, STAT1 and NEMO result in a common clinical phenotype known as Mendelian Susceptibility to Mycobacterial Diseases (MSMD). Interleukin-12 receptor beta1 (IL-12Rbeta1) deficiency is the most common genetic etiology for MSMD. Known mutations affecting IL12RB1 are recessively inherited and are associated with null response to both IL-12 and IL-23. Mutation IL12RB1 1623_1624delinsTT was originally described in 5 families from European origin (2 from Germany; 1 from Cyprus, France and Belgium). Interestingly, this same mutation was found in an unexpectedly high prevalence among IL-12Rbeta1 deficient patients in Argentina: 5-out-of-6 individuals born to unrelated families carried this particular change. To determine whether mutation 1623_1624delinsTT represents a DNA mutational hotspot or a founder effect, 34 polymorphic markers internal or proximal to IL12RB1 were studied in the Argentinean and the Belgian patients. A common haplotype spanning 1.45-3.51Mb was shared by all chromosomes carrying mutation 1623_1624delinsTT, and was not detected on 100 control chromosomes. Applying a modified likelihood-based method the age of the most recent common ancestor carrying mutation 1623_1624delinsTT was estimated in 475 years (95% CI, 175-1275), which is the time when the Spaniards initiated the colonization of the Americas. Mutation 1623_1624delinsTT represents the first founder effect described on IL-12Rbeta1, the most frequently affected gene in MSMD, and affecting patients with European ancestors. The reason(s) behind the persistency of this mutation across multiple generations, its relative high prevalence, and any potential selective advantage are yet to be established.
Infection, genetics and evolution: journal of molecular epidemiology and evolutionary genetics in infectious diseases 08/2009; 9(4):574-80. · 3.22 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: STAT5 proteins are components of the common growth hormone and interleukin 2 family of cytokines' signaling pathway. Mutations in the STAT5b gene, described in 2 patients, lead to growth hormone insensitivity that resembles Laron syndrome. Clinical immunodeficiency was also present, although immunologic defects have not been well characterized thus far. Here we describe a 16-year-old girl who suffered generalized eczema and recurrent infections of the skin and respiratory tract since birth. She also suffered severe chronic lung disease and multiple episodes of herpetic keratitis. Clinical features of congenital growth hormone deficiency were observed, such as persistently low growth rate, severely delayed bone age, and postnatal growth failure resulting from growth hormone resistance. This combined phenotype of growth hormone insensitivity and immunodeficiency was attributable to a homozygous C-->T transition that resulted in a nonsense mutation at codon 152 in exon 5 of the STAT5b gene. This novel mutation determined a complete absence of protein expression. The main immunologic findings were moderate T-cell lymphopenia (1274/mm3), normal CD4/CD8 ratio, and very low numbers of natural killer (18/mm3) and gammadelta T (5/mm3) cells. T cells presented a chronically hyperactivated phenotype. In vitro T-cell proliferation and interleukin 2 signaling were impaired. CD4+ and CD25+ regulatory T cells were significantly diminished, and they probably contributed to the signs of homeostatic mechanism deregulation found in this patient. This new case, in accordance with 2 previously reported cases, definitely demonstrates the significant role of the STAT5b protein in mediating growth hormone actions. Furthermore, the main immunologic findings bring about an explanation for the clinical immunodeficiency features and reveal for the first time the relevant role of STAT5b as a key protein for T-cell functions in humans.
[Show abstract][Hide abstract] ABSTRACT: CD4+ CD56+ malignancies have only recently been related to dendritic cell (DC) lineage. The few cases described, mostly adults and elderly, typically present with cutaneous lesions, followed by disseminated tumor localizations within a few months, with a generally very aggressive course and fatal outcome, despite the different therapeutic approaches employing chemotherapy and/or radiotherapy. Considering that leukemias in childhood and in adults are different diseases, we describe three pediatric cases to help compare the biological characteristics, immunophenotype, clinical features, treatment response and incidence of this disease in both age groups. From a total 1363 new patients with acute leukemia (AL), we report three cases with blasts of French - American - British L2 morphology, an absence of the most specific markers for myeloid, T or B lineage and lacking CD34, which led us to evaluate the blasts with an extensive panel of antibodies, including those related to the other putative pathways of lymphoid differentation: natural killer and DC. The cells expressed CD4, CD56, HLA-DR, BDCA-2 and BDCA-4. None of our cases presented with skin involvement. All three children showed good response to acute lymphoblastic leukemia (ALL) protocols, achieving complete remission even when one of the patients relapsed and received an allogeneic transplant. These findings, in spite of the small number of patients, suggest that the clinical course in children might be less aggressive, and that regular ALL protocols would be effective. We emphasize the importance of including antibodies for DC lineage in cases of CD34(-) unclassifiable AL to further characterize these rare cases (0.22%), considering that the tumor cell affiliation to DC lineage relies exclusively on immunophenotypic criteria.
Leukemia and Lymphoma 05/2006; 47(4):715-25. · 2.61 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Patients with mutations in the IFNgamma/IL-12 pathway show an exquisite susceptibility to mycobacterial diseases. An IL-12Rbeta1 deficient patient with impaired intestinal absorption suffered from a 13 year culture-positive Mycobacterium bovis-BCG infection with acquired multidrug resistance. A combined parenteral and enteral anti-mycobacterial treatment, including recombinant IFNgamma, helped to clear his infection.
The Journal of infection 04/2006; 52(3):e69-72. · 4.13 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: T-cell depletion (TCD) of BM allows transplantation across HLA barriers. Although different methods are used throughout the world, the optimal application of TCD still remains unclear, partly due to the lack of thorough analyses of the cellular fractions eliminated or retained in each method, and their possible implications regarding GvHD, GvL, or engraftment. We have analyzed the phenotype of the successive fractions of 19 BM samples depleted by soybean lectin agglutination and sheep erythrocyte rosetting (elimination of T cells that form rosettes through CD2), focusing on the final fraction infused to patients.
Analysis was performed using three-color flow cytometry and strategies for optimal staining and individualism of the subsets of interest.
The relative composition of the lymphoid population varied significantly along the successive steps in TCD: at the agglutination step, B cells and CD4 T cells are greatly reduced, while natural killer cells (NK) and TCRgammadelta+ T are augmented. The rosetting steps imply the relative enrichment of CD2-dim T cells, together with a further rise in the proportion of NK and double-negative T cells frequently TCRgammadelta+.
The presence of minor subsets of CD2- TCRgammadelta+ and CD2- TCRalphabeta T cells has already been described in the peripheral blood of normal individuals. We report that, by using this method of TCD, CD2-dim T cells, frequently TCRgammadelta+, are retained in the grafts and infused in patients, together with NK cells as the main lymphoid population. We discuss the possible implications of these populations in the biology of the graft, regarding GvHD, GvL and engraftment.
[Show abstract][Hide abstract] ABSTRACT: Few cytogenetic data are available concerning the chromosomal constitution of post-transplant lymphomas. We report two paediatric cases of trisomy 3, as a primary anomaly, in post-transplant lymphoproliferative disease (PTLD) associated with B immunophenotype. Using cytogenetic analysis and fluorescence in situ hybridization on chromosome preparations, we found trisomy 3 in both patients and an extra X chromosome in one. Clinical, histological and immunophenotypical data are presented. Trisomy 3 has been observed in different types of non-Hodgkin's lymphomas but it is relatively rare in B-cell lymphomas, with the exception of marginal zone lymphoma and mantle cell lymphoma. To our knowledge, trisomy 3 is an uncommon cytogenetic finding in PTLD. Further cytogenetic studies of these lymphoproliferative disorders might contribute to evaluate the role of these chromosomal anomalies in the pathogenesis of this disease.
British Journal of Haematology 07/2002; 117(3):558-62. · 4.94 Impact Factor