CARD11 is a lymphocyte-specific scaffold molecule required for proper activation of B- and T-cells in response to antigen. Germline gain-of-function (GOF) mutations in the CARD11 gene cause a unique B cell lymphoproliferative disorder known as B cell Expansion with NF-κB and T cell Anergy (BENTA). In contrast, patients carrying loss-of-function (LOF), dominant negative (DN) CARD11 mutations present with severe atopic disease. Interestingly, both GOF and DN CARD11 variants cause primary immunodeficiency, with recurrent bacterial and viral infections, likely resulting from impaired adaptive immune responses. This report describes a unique four-generation family harboring a novel heterozygous germline indel mutation in CARD11 (c.701-713delinsT), leading to one altered amino acid and a deletion of 4 others (p.His234_Lys238delinsLeu). Strikingly, affected members exhibit both moderate B cell lymphocytosis and atopic dermatitis/allergies. Ectopic expression of this CARD11 variant stimulated constitutive NF-κB activity in T cell lines, similar to other BENTA patient mutations. However, unlike other GOF mutants, this variant significantly impeded the ability of wild-type CARD11 to induce NF-κB activation following antigen receptor ligation. Patient lymphocytes display marked intrinsic defects in B cell differentiation and reduced T cell responsiveness in vitro. Collectively, these data imply that a single heterozygous CARD11 mutation can convey both GOF and DN signaling effects, manifesting in a blended BENTA phenotype with atopic features. Our findings further emphasize the importance of balanced CARD11 signaling for normal immune responses.

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IL-21 is a key cytokine in development of B-cells into immunoglobulin-secreting cells. Abnormal signalling through the IL-21R/γc/JAK3/STAT3 pathway leads to defective humoral immune responses to both T-dependent and T-independent antigens and impairs the establishment of long-lasting B-cell memory. Studies involving patients with hyper-IgE syndrome demonstrated the nonredundant role of STAT3 in B-cell production of high-affinity specific antibodies, while total serum immunoglobulins could be maintained through STAT3-independent activation of AID (activation-induced cytidine-deaminase). IL-21 related defects may also be associated with reduced natural killer (NK)-cell cytotoxicity and TH17 cytokine production, indicating that abnormalities in the IL-21-IL-21R pathway have profound effects on crucial immune responses.

The IL-4 and IL-21 in vitro assays distinguish two groups of CVID subjects and can be used with baseline B cell subpopulation phenotyping to better identify patients experiencing more vs. fewer clinical non-infectious complications and potentially to modulate therapy.

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in a young African man presenting with a pleural effusion. Can Respir J 2006;13(8):441-444.Blastomyces dermatitidis is a dimorphic fungus endemic to northwestern Ontario, Manitoba and some parts of the United States. The fungus is also endemic to parts of Africa. Pulmonary and extrapulmonary findings of a 24-year-old African man who presented with weight loss, dry cough and chronic pneumonia not resolving with antibiotic treatment are presented. The unusual occurrence of pulmonary blastomycosis associated with skin lesions and a moderate pleural effusion is reported. CASE PRESENTATIONA 24-year-old previously healthy man from Tanzania presented with a three-month history of dry cough, fatigue and fever. He was treated empirically for a community-acquired pneumonia; however, after two courses of antibiotic treatment he did not improve clinically, and had a worsening chest radiograph showing a large unilateral pleural effusion. His vital signs, however, were normal. Other clinical features included a 14 kg weight loss and scaling papulonodular skin lesions on the nose ( Figure 1A), right hand ( Figure 1B) and right forearm. In addition to the skin lesions, he also had a raised subcutaneous nodular lesion on his left buttock and left upper arm suppuration. InvestigationsOn admission, the patient's white blood cell count was 13.5×10 9 /L, hemoglobin level was 117 g/L, platelet count was 584×10 9 /L and serum albumin level was 30 g/L. Electrolytes, renal function and liver enzyme levels were normal. HIV serology was negative. Sputum initially showed heavy growth of normal respiratory flora; no acid-fast bacilli were seen. A pigtail catheter was inserted to drain the right pleural fluid which showed a pH of 8, glucose level of 5.6 mmol/L, total protein concentration of 62 g/L and lactate dehydrogenase level of 152 U/L. Pleural fluid white blood cell differential showed 31% neutrophils, 61% lymphocytes, 7% monocytes and 1% eosinophils. The pleural fluid was consistent with an exudate. Bronchoscopy washings were negative for Gram and fungal stains. Radiographs of the pelvis and femur were normal. A plain chest radiograph showed a moderate-sized right pleural effusion on posteroanterior view (Figure 2A) and some ill-defined soft tissue nodules in the lateral aspect of the left upper lung zone. An enhanced axial computed tomography of the thorax in the mediastinal window settings confirmed a moderate-sized right pleural effusion with multiple well-defined soft tissue nodules over the parietal pleura projecting into the pleural cavity, which was better seen over the diaphragmatic surface ( Figure 2B). No significant mediastinal lymphadenopathy was noted. On the lung window settings, centrilobular nodules in a tree-in-bud pattern at the apicoposterior segment of the left upper lobe were present. Consolidative changes of the lateral segment of the right middle lobe and the right lower lobe were also seen. Hospital courseThe patient was from an area endemic for HIV and tuberculosis, and had significant weight loss, mild anem...

BackgroundSemaphorins are important molecules in embryonic development and multiple semaphorins have been identified as having key roles in immune regulation. To date, there is little known about Semaphorin 4C (Sema4C) in immune biology. We report for the first time that Sema4C is inducible in human and murine B-cells and may be important for normal B-cell development.MethodsHuman tonsillar B-cells were studied following activation via anti-CD40 antibodies in the presence or absence of representative Th1, Th2, and regulatory cytokines. Murine B-cells from WT and Sema4C−/− mice were similarly stimulated. B-cell phenotyping in WT and Sema4C mutant mice was performed by flow cytometry and lymphoid architecture was studied by immunohistochemistry. Sema4C expression and synapse formation were analyzed by confocal microscopy.ResultsGene array studies performed on human tonsillar B-cells stimulated to produce IgE revealed that Sema4C was among the top genes expressed at 24 h, and the only semaphorin to be increased under Th2 conditions. Validation studies demonstrated that human and murine B-cells expressed Sema4C under similar conditions. Sema4C−/− mice had impaired maturation of B-cell follicles in spleens and associated decreases in follicular and marginal zone B-cells as well as impaired IgG and IgA production. In keeping with a potential role in maturation of B-cells, Sema4C was expressed predominantly on CD27+ human B-cells. Within 72 h of B-cell activation, Sema4C was localized to one pole in a synapse-like structure, in association with F-actin, B-cell receptor, and Plexin-B2. Cell polarization was impaired in Sema4C−/− mice.ConclusionWe have identified a novel immune semaphorin induced in human and murine B-cells under Th2 conditions. Sema4C appears to be a marker for human memory B-cells. It may be important for B-cell polarization and for the formation of normal splenic follicles.

Background Acute airway angioedema commonly occurs through two distinct mechanisms: histamine- and bradykinin-dependent. Although they respond to distinct treatments, these two potentially life-threatening states present similarly. Poor recognition of the bradykinin-dependent pathway leads to treatment errors in the emergency department (ED), despite the availability of multiple pharmacologic options for hereditary angioedema (HAE) and other forms of bradykinin-induced angioedema. Here, we consider the pathophysiology and clinical features of bradykinin-induced angioedema, and we present a systematic literature review exploring the effectiveness of the available therapies for managing such cases. Methods PubMed searches using ‘emergency’, ‘bradykinin’ and various therapeutic product names identified studies reporting the efficacy of treatments for bradykinin-induced angioedema in the ED setting. In all, 22 studies met prespecified criteria and are analysed here. Findings Whereas histamine-induced angioedema has a faster onset and often presents with urticaria, bradykinin-induced angioedema is slower in onset, with greater incidence of abdominal symptoms. Acute airway angioedema in the ED should initially be treated with anaphylactic protocols, focusing on airway management and treatment with epinephrine, antihistamine and systemic steroids. Bradykinin-induced angioedema should be considered if this standard treatment is not effective, despite proper dosing and regard of beta-adrenergic blockade. Therapeutics currently approved for HAE appear as promising options for this and other forms of bradykinin-induced angioedema encountered in the ED. Conclusion Diagnostic algorithms of bradykinin-induced angioedema should be followed in the ED, with early use of approved therapies to improve patient outcomes.