Loss of function NFKB1 variants are the most common monogenic cause of CVID in Europeans

BACKGROUND: The genetic etiology of primary immunodeficiency disease (PID) carries prognostic information. OBJECTIVE: We conducted a whole-genome sequencing study assessing a large proportion of the NIHR-BioResource - Rare Disease cohort. METHODS: In the predominantly European study population of principally sporadic unrelated PID cases (n=846), a novel Bayesian method identified NFKB1 as one most strongly associated with PID, and the association was explained by 16 novel heterozygous truncating, missense and gene deletion variants. This accounted for 4% of common variable immunodeficiency (CVID) cases (n=390) in the cohort. Amino-acid substitutions predicted to be pathogenic were assessed by analysis of structural protein data. Immunophenotyping, immunoblotting and ex vivo stimulation of lymphocytes determined the functional effects of these variants. Detailed clinical and pedigree information was collected for genotype-phenotype co-segregation analyses. RESULTS: Both sporadic and familial cases demonstrated evidence of the non-infective complications of CVID, including massive lymphadenopathy (24%), unexplained splenomegaly (48%) and autoimmune disease (48%), features prior studies correlate with worse clinical prognosis. Although partial penetrance of clinical symptoms was noted in certain pedigrees, all carriers have a deficiency in B lymphocyte differentiation. Detailed assessment of B lymphocyte numbers, phenotype and function identifies the presence of a raised CD21lowB cell population: combined with identification of the disease-causing variant, this distinguishes between healthy individuals, asymptomatic carriers and clinically affected cases. CONCLUSION: We show that heterozygous loss-of-function variants in NFKB1 are the most common known monogenic cause of CVID that results in a temporally progressive defect in the formation of immunoglobulin-producing B cells

Bactericidal permeability-increasing protein release in whole blood ex vivo: Strong induction by lipopolysaccharide and tumor necrosis factor-alpha.

Department of Pulmonology, University of Limburg, Maastricht, Netherlands. In this study, the release of bactericidal/permeability-increasing protein (BPI), which is stored in polymorphonuclear leukocytes (PMNL), was analyzed in a whole blood ex vivo system. Of the microbial products tested, lipopolysaccharide (LPS) most potently induced BPI release; FMLP, serum-treated zymosan (STZ), and lipoteichoic acid (LTA) also induced BPI release. In addition, the inflammatory mediator tumor necrosis factor (TNF)-alpha potently activated PMNL in whole blood, via TNF receptor p55, to release BPI, whereas interleukin (IL)-1, IL-8, platelet activating factor, and C5a were poor inducers of BPI release. STZ and phorbol myristate acetate, but not LPS, FMLP, or LTA, stimulated isolated PMNL to release BPI. BPI was released in comparable magnitude with the azurophilic granule protein elastase. Furthermore, both proteins were released with similar kinetics, which started within 30 min after onset of stimulation and lasted 1-4 h

Apoptotic neutrophils in the circulation of patients with glycogen storage disease type 1b (GSD1b)

Glycogen storage disease type 1b (GSD1b) is a rare autosomal recessive disorder characterized by hypoglycemia, hepatomegaly, and growth retardation, and associated-for unknown reasons-with neutropenia and neutrophil dysfunction. In 5 GSD1b patients in whom nicotinamide adenine dinucleotide phosphate-oxidase activity and chemotaxis were defective, we found that the majority of circulating granulocytes bound Annexin-V. The neutrophils showed signs of apoptosis with increased caspase activity, condensed nuclei, and perinuclear clustering of mitochondria to which the proapoptotic Bcl-2 member Bax had translocated already. Granulocyte colony-stimulating factor (G-CSF) addition to in vitro cultures did not rescue the GSD1b neutrophils from apoptosis as occurs with G-CSF-treated control neutrophils. Moreover, the 2 GSD1b patients on G-CSF treatment did not show significantly lower levels of apoptotic neutrophils in the bloodstream. Current understanding of neutrophil apoptosis and the accompanying functional demise suggests that GSD1b granulocytes are dysfunctional because they are apoptotic. (C) 2003 by The American Society of Hematology

Interference of PR3-ANCA with the enzymatic activity of PR3: differences in patients during active disease or remission of Wegener's granulomatosis

Anti-neutrophil cytoplasmic antibodies (ANCA) against proteinase 3 (PR3) are strongly associated with Wegener's granulomatosis (WG) and are thought to be involved in its pathogenesis. Levels of PR3-ANCA do not always correspond to clinical disease activity. To investigate the relationship between functional effects of PR3-ANCA and disease activity, we tested the effect of IgG samples from sera of 43 WG patients, taken during active disease or remission, for their capacity to interfere with the proteolytic activity of PR3. Furthermore, longitudinal sera of seven WG patients were included. The enzymatic activity of PR3 was determined (1) with casein or with a small synthetic substrate and (2) by complexation of PR3 with alpha1-antitrypsin (alpha1-AT). With a fixed concentration (100 mug/ml) of IgG, PR3-ANCA from patients during an active phase of WG had a higher inhibitory capacity towards the proteolytic activity of PR3 and complexation of PR3 with alpha1-AT than did PR3-ANCA from WG patients during remission. However, the number of PR3-ANCA units that gave 50% inhibition of the PR3 enzymatic activity and its complexation with alpha1-AT was lower for patients during remission than for patients during an active phase of WG, indicating a stronger inhibitory capacity at a molar base. In conclusion, PR3-ANCA from patients during remission had a relatively higher inhibitory capacity towards the enzymatic activity of PR3 than PR3-ANCA from patients during an active phase. This may indicate that during active disease the ANCA titre is increased, but the number of active ANCA molecules that recognize the enzyme-inhibiting epitopes is not increased