Figen Dogu

Mutations in STAT3 and IL12RB1 impair the development of human IL-17–producing T cells

The cytokines controlling the development of human interleukin (IL) 17–producing T helper cells in vitro have been difficult to identify. We addressed the question of the development of human IL-17–producing T helper cells in vivo by quantifying the production and secretion of IL-17 by fresh T cells ex vivo, and by T cell blasts expanded in vitro from patients with particular genetic traits affecting transforming growth factor (TGF) β, IL-1, IL-6, or IL-23 responses. Activating mutations in TGFB1, TGFBR1, and TGFBR2 (Camurati-Engelmann disease and Marfan-like syndromes) and loss-of-function mutations in IRAK4 and MYD88 (Mendelian predisposition to pyogenic bacterial infections) had no detectable impact. In contrast, dominant-negative mutations in STAT3 (autosomal-dominant hyperimmunoglobulin E syndrome) and, to a lesser extent, null mutations in IL12B and IL12RB1 (Mendelian susceptibility to mycobacterial diseases) impaired the development of IL-17–producing T cells. These data suggest that IL-12Rβ1– and STAT-3–dependent signals play a key role in the differentiation and/or expansion of human IL-17–producing T cell populations in vivo.

Inherited IL-17RC deficiency in patients with chronic mucocutaneous candidiasis

Autosomal-recessive IL-17RA, IL-17RC, and ACT1 deficiencies and autosomal-dominant IL-17F deficiency in humans underlie susceptibility to chronic mucocutaneous candidiasis.

Inherited and acquired immunodeficiencies underlying tuberculosis in childhood.

Tuberculosis (TB), caused by Mycobacterium tuberculosis (M.tb) and a few related mycobacteria, is a devastating disease, killing more than a million individuals per year worldwide. However, its pathogenesis remains largely elusive, as only a small proportion of infected individuals develop clinical disease either during primary infection or during reactivation from latency or secondary infection. Subacute, hematogenous, and extrapulmonary disease tends to be more frequent in infants, children, and teenagers than in adults. Life‐threatening primary TB of childhood can result from known acquired or inherited immunodeficiencies, although the vast majority of cases remain unexplained. We review here the conditions conferring a predisposition to childhood clinical diseases caused by mycobacteria, including not only M.tb but also weakly virulent mycobacteria, such as BCG vaccines and environmental mycobacteria. Infections with weakly virulent mycobacteria are much rarer than TB, but the inherited and acquired immunodeficiencies underlying these infections are much better known. Their study has also provided genetic and immunological insights into childhood TB, as illustrated by the discovery of single‐gene inborn errors of IFN‐γ immunity underlying severe cases of TB. Novel findings are expected from ongoing and future human genetic studies of childhood TB in countries that combine a high proportion of consanguineous marriages, a high incidence of TB, and an excellent clinical care, such as Iran, Morocco, and Turkey.

Early-onset inflammatory bowel disease and common variable immunodeficiency–like disease caused by IL-21 deficiency

BACKGROUND Alterations of immune homeostasis in the gut can result in development of inflammatory bowel disease (IBD). Recently, Mendelian forms of IBD have been discovered, as exemplified by deficiency of IL-10 or its receptor subunits. In addition, other types of primary immunodeficiency disorders might be associated with intestinal inflammation as one of their leading clinical presentations. OBJECTIVE We investigated a large consanguineous family with 3 children who presented with early-onset IBD within the first year of life, leading to death in infancy in 2 of them. METHODS Homozygosity mapping combined with exome sequencing was performed to identify the molecular cause of the disorder. Functional experiments were performed to assess the effect of IL-21 on the immune system. RESULTS A homozygous mutation in IL21 was discovered that showed perfect segregation with the disease. Deficiency of IL-21 resulted in reduced numbers of circulating CD19(+) B cells, including IgM(+) naive and class-switched IgG memory B cells, with a concomitant increase in transitional B-cell numbers. In vitro assays demonstrated that mutant IL-21(Leu49Pro) did not induce signal transducer and activator of transcription 3 phosphorylation and immunoglobulin class-switch recombination. CONCLUSION Our study uncovers IL-21 deficiency as a novel cause of early-onset IBD in human subjects accompanied by defects in B-cell development similar to those found in patients with common variable immunodeficiency. IBD might mask an underlying primary immunodeficiency, as illustrated here with IL-21 deficiency.

Genetic, immunological, and clinical features of patients with bacterial and fungal infections due to inherited IL-17RA deficiency

Significance Chronic mucocutaneous candidiasis (CMC) is defined as persistent or recurrent infections of the skin and/or mucosae by commensal fungi of the Candida genus. It is often seen in patients with T-cell deficiencies, whether inherited or acquired, who typically suffer from multiple infectious diseases. Rare patients are otherwise healthy and display isolated CMC, which often segregates as a Mendelian trait. In 2011, we described the first genetic cause of isolated CMC, with autosomal recessive (AR), complete IL-17 receptor A (IL-17RA) deficiency, in a single patient. We report here 21 patients from 12 unrelated kindreds, homozygous for 12 different mutant alleles that underlie AR IL-17RA deficiency. All patients have isolated CMC and their cells do not respond to IL-17A, -17F, and -17E/IL-25. Chronic mucocutaneous candidiasis (CMC) is defined as recurrent or persistent infection of the skin, nails, and/or mucosae with commensal Candida species. The first genetic etiology of isolated CMC—autosomal recessive (AR) IL-17 receptor A (IL-17RA) deficiency—was reported in 2011, in a single patient. We report here 21 patients with complete AR IL-17RA deficiency, including this first patient. Each patient is homozygous for 1 of 12 different IL-17RA alleles, 8 of which create a premature stop codon upstream from the transmembrane domain and have been predicted and/or shown to prevent expression of the receptor on the surface of circulating leukocytes and dermal fibroblasts. Three other mutant alleles create a premature stop codon downstream from the transmembrane domain, one of which encodes a surface-expressed receptor. Finally, the only known missense allele (p.D387N) also encodes a surface-expressed receptor. All of the alleles tested abolish cellular responses to IL-17A and -17F homodimers and heterodimers in fibroblasts and to IL-17E/IL-25 in leukocytes. The patients are currently aged from 2 to 35 y and originate from 12 unrelated kindreds. All had their first CMC episode by 6 mo of age. Fourteen patients presented various forms of staphylococcal skin disease. Eight were also prone to various bacterial infections of the respiratory tract. Human IL-17RA is, thus, essential for mucocutaneous immunity to Candida and Staphylococcus, but otherwise largely redundant. A diagnosis of AR IL-17RA deficiency should be considered in children or adults with CMC, cutaneous staphylococcal disease, or both, even if IL-17RA is detected on the cell surface.

Combined immunodeficiency and Epstein-Barr virus?induced B cell malignancy in humans with inherited CD70 deficiency

In this study, we describe four patients from two unrelated families of different ethnicities with a primary immunodeficiency, predominantly manifesting as susceptibility to Epstein-Barr virus (EBV)–related diseases. Three patients presented with EBV-associated Hodgkin’s lymphoma and hypogammaglobulinemia; one also had severe varicella infection. The fourth had viral encephalitis during infancy. Homozygous frameshift or in-frame deletions in CD70 in these patients abolished either CD70 surface expression or binding to its cognate receptor CD27. Blood lymphocyte numbers were normal, but the proportions of memory B cells and EBV-specific effector memory CD8+ T cells were reduced. Furthermore, although T cell proliferation was normal, in vitro–generated EBV-specific cytotoxic T cell activity was reduced because of CD70 deficiency. This reflected impaired activation by, rather than effects during killing of, EBV-transformed B cells. Notably, expression of 2B4 and NKG2D, receptors implicated in controlling EBV infection, on memory CD8+ T cells from CD70-deficient individuals was reduced, consistent with their impaired killing of EBV-infected cells. Thus, autosomal recessive CD70 deficiency is a novel cause of combined immunodeficiency and EBV-associated diseases, reminiscent of inherited CD27 deficiency. Overall, human CD70–CD27 interactions therefore play a nonredundant role in T and B cell–mediated immunity, especially for protection against EBV and humoral immunity.

Is immune system influenced by adenotonsillectomy in children

OBJECTIVE Tonsils and adenoids are lymphoid tissues that are located in the pharynx and play an important role against invading antigens of the upper respiratory tract. The present study analyses serum immunoglobulin levels and peripheral blood (PB) lymphocyte subsets in children, 24-48 h prior to and 4-6 weeks after adenotonsillectomy, in order to determine early effects of adenotonsillectomy on the immune system. METHODS The study population consists of 15 children (aged 4-10 years) who underwent adenotonsillectomy because of adenoidal hypertrophy and chronic tonsillitis and 15 age-matched healthy children without a history of adenotonsillectomy. Serum IgG, IgA and IgM levels were measured by nephelometry. PB lymphocyte subsets were analysed by using monoclonal antibodies and flow cytometry. RESULTS Children with chronic tonsillitis have increased levels of CD19+ B lymphocytes compared to healthy controls in the pre-operative period. The percentage of B lymphocytes bearing CD23 was found to be significantly higher in patients, most likely representing in vivo B lymphocyte activation due to chronic antigenic stimulation. After the adenotonsillectomy, despite ongoing B lymphocyte activation, CD8+ T lymphocyte levels increased and B cell levels returned to normal. A slight decrease in serum IgG, IgA and IgM levels was detected in the post-operative period compared to prior levels. CONCLUSION Adenotonsillectomy performed in children leads to alterations that may reflect a compensatory response of the developing immune system after the removal of the lymphoid tissue in the setting of chronic antigenic stimulation. However, these changes do not cause significant immune deficiency.

Granulocyte Transfusions in Children With Chronic Granulomatous Disease and Invasive Aspergillosis

Abstract:  The transfusion of granulocytes to restore host defenses in severely granulocytopenic patients or in patients with defective granulocyte functions has been studied for more than 60 years. However, inadequate dosage of cells and inconsistent efficacy has limited the usage of these transfusions. Recently, the use of mobilizing agents such as granulocyte colony stimulating factors and dexamethasone has renewed interest in these treatment modalities. The present study is conducted to determine an appropriate method of enriched granulocyte collection with Fresenius AS.TEC.204 cell separator (Fresenius, Bad Homburg, Germany) and to evaluate the preliminary clinical results of granulocyte transfusion therapy in patients with chronic granulomatous disease and invasive Aspergillosis in parallel with in vitro granulocyte function. Three patients who have been treated for chronic granulomatous disease and invasive Aspergillosis received a total of 20 granulocyte transfusions. To mobilize granulocytes, healthy donors were given 450 µg of granulocyte colony‐stimulating factor (G‐CSF) subcutaneously and 8 mg of dexamethasone orally approximately 12 h before collection. Five µg/kg/day of G‐CSF was also subcutaneously administered prior to granulocyte transfusions. The first patient received 4; the second, 14 and the third, 2 transfusions. The granulocyte count given to these patients ranged between 0.4 and 3.0 × 109/kg. Most transfusions were well tolerated. The nitroblue tetrazolium (NBT) tests that were done 16–24 h after the transfusion showed 14–46% dye reduction. Two of the three patients survived the infection. Granulocyte transfusions from G‐CSF and dexamethasone stimulated donors could be a choice of treatment in chronic granulomatous disease patients, especially with disseminated invasive Aspergillosis.

Oral Lactoferrin to Prevent Nosocomial Sepsis and Necrotizing Enterocolitis of Premature Neonates and Effect on T-Regulatory Cells

OBJECTIVE Lactoferrin (LF) is effective in the prevention of sepsis in very low birth weight (VLBW) neonates. T-regulatory cells (Tregs) are important subsets of T lymphocytes that control pathogen-specific immune responses and are essential for intestinal immune homoeostasis. The aim of the present study is to determine whether oral LF at a dosage of 200 mg/d reduces nosocomial sepsis episodes and necrotizing enterocolitis (NEC) in premature infants and to evaluate the possible effects of LF on Treg levels. STUDY DESIGN In this prospective, placebo-controlled, double-blind, randomized trial, infants either VLBW or born before 32 weeks were assigned to receive either placebo (n = 25), or 200 mg LF (n = 25) daily throughout hospitalization. Episodes of culture proven nosocomial sepsis and NEC were recorded. The level of FOXP3 + CD4 + CD25hi lymphocytes was studied by flow cytometry at birth and discharge. A third comparison was made with healthy term neonates (n = 16). RESULTS Fewer sepsis episodes were observed in LF-treated infants (4.4 vs. 17.3/1,000 patient days, p = 0.007) with none developing NEC, without statistical significance. Treg levels at birth and discharge were similar, while preterm infants showed significantly lower levels than term controls. However, individual increases in Treg levels were higher in the LF group. CONCLUSION LF prophylaxis reduced nosocomial sepsis episodes. Treg levels in preterm infants were lower than in term infants and an increase of Treg levels under LF prophylaxis was observed. Increase in Treg levels can be the mechanism for protective effects of LF on nosocomial sepsis.

A Successful HSCT in a Girl with Novel LRBA Mutation with Refractory Celiac Disease

To the Editor The gastrointestinal tract is the largest lymphoid organ in the body. One of the major functions of the gastrointestinal tract is maintaining of the balance between active immunity, tolerance and immunosuppression. Dysregulation of this physiologic process can lead to diseases such as food allergy, celiac disease (CD) or inflammatory bowel disease [1]. Therefore, gastrointestinal symptoms such as chronic diarrhea and malabsorption might be indicative of primary immunodeficiency diseases [1]. A 10-year-old girl referred to our clinic with a six-year history of chronic watery diarrhea and unresponsiveness to a gluten free diet. She had been evaluated and treated previously for chronic diarrhea, intermittent fever, recurrent pneumonia, candida esophagitis, pancytopenia, hypoalbuminemia, hypolipidemia, vitamin B12 and folic acid deficiencies. She was diagnosed with CD, based on serologic and histopathological findings. She was placed on a strict gluten free diet for a year, but diarrhea did not improve. She has two healthy brothers. Her parents were consanguineous. On physical examination, she was cachectic; with height for age below 3 % (height SDS −5.18) and weight for age below 3 % (weight SDS −5.27). Bone age and height age of the patient were 6 years, 10 months and 5 years, 3 months, respectively. She had protuberant abdomen and clubbing. Liver and spleenwere palpable at 1 cm and 4 cm below the costal margins. Laboratory tests revealed mildly increased liver transaminases. Hemoglobin was 8.32 g/dl; MCV, 85 fL; RDW, 23.4 %; white blood cell, 5570/mm; platelet, 230,000/mm; reticulocyte count, 1 % and ferritin, 2.8 ng/ml. Coombs test was negative. Sedimentation rate was 18 mm/h, C-reactive protein, 1.78 mg/dl. Stool examinations were normal. 25-hydroxi vitamin D level was 25.7 ng/ml. Insulin like growth factor 1 (IGF-1) was 3.5 ng/mL (Normal, 108–648 ng/mL) and insulin like growth factor binding protein (IGFBP-3), 580 ng/mL (Normal, 2690–7200 ng/mL). Stimulated IGF-1 and IGFBP-3 were 2.85 ng/mL and 720 ng/mL, respectively, both markedly reduced. Basal and stimulated growth hormone levels were compatible with growth hormone insensitivity (12.9 ng/mL and 9.79 ng/mL, respectively). Anti-tissue transglutaminase IgA was positive with a titer of 200 IU/ml. Thyroid auto-antibodies, anti-saccharomyces cerevicea antibody and pANCA were negative. Bone mineral density showed severe osteoporosis (Z score, −5). Chest X-ray showed reticular density in the parenchyma of the lung. High-resolution chest tomography showed bilateral tubular bronchiectasis. Smear staining for acid resistant bacteria and tuberculosis PCR, and culture were negative. Upper gastrointestinal endoscopic examination revealed scalloping in the duodenal mucosa. Colonoscopy showed nonspecific Buket Dalgic and Aydan Ikinciogullari contributed equally to this work.