The IL-2RG R328X nonsense mutation allows partial STAT-5 phosphorylation and defines a critical region involved in the leaky-SCID phenotype.

In addition to their detection in typical X-linked severe combined immunodeficiency, hypomorphic mutations in the interleukin (IL)-2 receptor common gamma chain gene (IL2RG) have been described in patients with atypical clinical and immunological phenotypes. In this leaky clinical phenotype the diagnosis is often delayed, limiting prompt therapy in these patients. Here, we report the biochemical and functional characterization of a nonsense mutation in exon 8 (p.R328X) of IL2RG in two siblings: a 4-year-old boy with lethal Epstein-Barr virus-related lymphoma and his asymptomatic 8-month-old brother with a Tlow B+ natural killer (NK)+ immunophenotype, dysgammaglobulinemia, abnormal lymphocyte proliferation and reduced levels of T cell receptor excision circles. After confirming normal IL-2RG expression (CD132) on T lymphocytes, signal transducer and activator of transcription-1 (STAT-5) phosphorylation was examined to evaluate the functionality of the common gamma chain (γc ), which showed partially preserved function. Co-immunoprecipitation experiments were performed to assess the interaction capacity of the R328X mutant with Janus kinase (JAK)3, concluding that R328X impairs JAK3 binding to γc . Here, we describe how the R328X mutation in IL-2RG may allow partial phosphorylation of STAT-5 through a JAK3-independent pathway. We identified a region of three amino acids in the γc intracellular domain that may be critical for receptor stabilization and allow this alternative signaling. Identification of the functional consequences of pathogenic IL2RG variants at the cellular level is important to enable clearer understanding of partial defects leading to leaky phenotypes.

Pseudomonas aeruginosa liver abscess as the first manifestation of X-Linked agammaglobulinemia with a novel mutation

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Determination of neutrophil CD64 expression as a prognostic biomarker in patients with community-acquired pneumonia.

The expression of CD64 in neutrophils (nCD64) has shown utility in the diagnosis of sepsis. The aim of this study was to assess the usefulness of nCD64 expression to identify patients with community-acquired pneumonia (CAP) at risk of a poor outcome. A prospective study of nCD64 expression (determined by flow cytometry) in patients with CAP was performed. The sensitivity/specificity of nCD64 in predicting poor outcome [defined as intensive care unit (ICU) admission and/or clinical deterioration after arrival at the emergency department] was calculated. Eighty-three adults with CAP were included; 14.5 % had septic shock, 19.3 % required ICU admission, and 10.8 % presented clinical deterioration after admission. The mean of the median fluorescence intensity (MFI) of nCD64 expression was 1140 (±1097). Patients with nCD64 expression ≥2700 MFI had more clinical deterioration (36.4 vs. 7.2 %, p = 0.015) and more ICU admission (45.5 vs. 14.5 %, p = 0.028). To identify clinical deterioration and ICU admission, nCD64 expression showed a sensitivity of 44.4 and 33.3 % and a specificity of 90.1 and 90.8 %, respectively. The addition of nCD64 expression to the Pneumonia Severity Index and CURB-65 severity scores did not improve the accuracy of predicting these outcomes. Although nCD64 expression is associated with an increased risk of ICU admission or clinical deterioration after admission, its accuracy in predicting these poor outcomes is modest and does not significantly improve the predictive ability of the PSI and CURB-65 severity scores.

Novel and atypical splicing mutation in a compound heterozygous UNC13D defect presenting in Familial Hemophagocytic Lymphohistiocytosis triggered by EBV infection.

Familial Hemophagocytic Lymphohistiocytosis type 3 (FHL3) is a genetic disorder caused by mutations in UNC13D gene, coding the granule priming factor Munc13-4 that intervenes in NK and T cell cytotoxic function. Here we report the case of a 17-month-old girl with prolonged symptomatic EBV infectious mononucleosis and clinical symptoms of hemophagocytic syndrome. In vitro functional analysis pointed to a degranulation defect. The genetic analysis of UNC13D gene identified initially a heterozygous mutation (c.753+1G>T) in the donor splice-site that resulted in exon 9 skipping (maternal allele). Mutations in other genes were considered, but additional analysis of UNC13D cDNA revealed in the paternal allele a heterozygous transition from G to A (c.2448-13G>A) at the 3' acceptor splice-site in intron 25, generating a new acceptor splice-site that leads to a frameshift and a premature STOP codon. Allele specific amplification of the cDNA confirmed the absence of a functional mRNA from the paternal allele. This case illustrates an atypical compound heterozygous UNC13D mutation affecting the RNA splicing that generates a typical FHL3 phenotype.

Identification and biochemical characterization of the novel mutation m.8839G>C in the mitochondrial ATP6 gene associated with NARP syndrome.

Mutations in the ATP6 gene are reported to be associated with Leber hereditary optic neuropathy, bilateral striatal necrosis, coronary atherosclerosis risk and neuropathy, ataxia and retinitis pigmentosa (NARP)/maternally inherited Leigh syndromes. Here, we present a patient with NARP syndrome, in whom a previously undescribed mutation was detected in the ATP6 gene: m.8839G>C. Several observations support the concept that m.8839G>C is pathogenically involved in the clinical phenotype of this patient: (1) the mutation was heteroplasmic in muscle; (2) mutation load was higher in the symptomatic patient than in the asymptomatic carriers; (3) cybrids carrying this mutation presented lower cell proliferation, increased mitochondrial DNA (mtDNA) copy number, increased steady-state OxPhos protein levels and decreased mitochondrial membrane potential with respect to isogenic wild-type cybrids; (4) this change was not observed in 2959 human mtDNAs from different mitochondrial haplogroups; (5) the affected amino acid was conserved in all the ATP6 sequences analyzed; and (6) using in silico prediction, the mutation was classified as 'probably damaging'. However, measurement of ATP synthesis showed no differences between wild-type and mutated cybrids. Thus, we suggest that m.8839G>C may lower the efficiency between proton translocation within F0 and F1 rotation, required for ATP synthesis. Further experiments are needed to fully characterize the molecular mechanisms involved in m.8839G>C pathogenicity.

Severe and recurrent episodes of bronchiolitis obliterans organising pneumonia associated with indolent CD4+ CD8+ T-cell leukaemia.

The present study describes an adult male who has had recurrent episodes of pulmonary infiltrates with severe acute respiratory failure over a period of 10 yrs. Clinical and pathological characteristics revealed bronchiolitis obliterans with organising pneumonia (BOOP) that responded dramatically to prednisone. BOOP is characterised by inflammation of the bronchioles and surrounding tissue in the lungs. It can mimic infectious pneumonia but diagnosis is suspected when there is no response to multiple antibiotic treatment, and blood and sputum cultures are negative for microorganisms. A high proportion of double-positive (DP)-T-cells was detected in peripheral blood and in bronchoalveolar lavage, expressing CD4 and CD8alphabeta heterodimer with memory phenotype. These DP-T-lymphocytes expressed specific homing molecules that could explain their tropism to lung tissue, giving rise to the clinical symptoms. The patient did not present organomegaly, lymphadenopathy, lymphocytosis or other features of malignancy. However, T-cell receptor Vbeta chain analysis indicated clonal rearrangement, and cytogenetic studies displayed chromosomic alterations that were similar to clonal proliferation observed in ataxia-telangiectasia and T-prolymphocytic leukaemia. The findings suggest a smouldering form of lymphoproliferation, the first sign of which was bronchiolitis obliterans organising pneumonia requiring constant corticoid treatment.

Identification of a novel HLA-DRB1 allele, DRB1*0108, by sequence-based DRB typing in two siblings.

We report here a novel DRB1 allele identified during sequence-based HLA-DRB typing. This allele was detected during routine HLA typing of a patient and his family prior to bone marrow transplantation. The new allele, DRB1*0108, was found in the patient and in a brother. Molecular cloning and sequencing confirmed that the new DRB1 allele is identical to DRB1*0101 at exon 2 except for a single nucleotide substitution at codon 37 (TauCC-->TauAlphaC), changing the encoded serine to tyrosine. This position of the beta1 domain lies in the floor of the antigen-binding groove and shows the highest polymorphism among DRB1 alleles.

[The use of thymostimulin in lymphoma and myeloma patients]. / Utilización de la timoestimulina en pacientes con mieloma y linfoma.

The benefit of the immunomodulation properties of thymic hormones in patients receiving chemotherapy for malignant diseases is yet to be defined. The efficacy of thymostimulin (TP-1) on hematological tolerance is evaluated, the performance level, the number and severity of the infections and skin reactions in two groups of homogeneous and randomized patients, diagnosed as having lymphoma and myeloma. Both patient groups (receiving or not receiving treatment) consisted of 20 persons. This observation was carried out in 96 courses of chemotherapy in each group; no significant differences having been noted in respect of the performance status at the beginning nor at the end of the study period between the 2 treatment groups. The hematological tolerance to chemotherapy, skin reactions and number and severity of infections registered were not significantly different between the 2 groups. In conclusion, we were unable to confirm an improvement in the clinical parameters of the myeloma and lymphoma patients receiving chemotherapy and thymostimulin during the period of observation.