Local Clonal Diversification and Dissemination of B Lymphocytes in the Human Bronchial Mucosa

The efficacy of the adaptive humoral immune response likely requires diverse, yet focused regional B cell antibody production throughout the body. Here we address, in the first study of its kind, the B cell repertoire in the bronchial mucosa, an important barrier to antigens inhaled from the atmosphere. To accomplish this, we have applied high-throughput Adaptive Immune Receptor Repertoire Sequencing (AIRR-Seq) to 10 bronchial biopsies from altogether four different sites in the right lungs from an asthmatic patient and a healthy subject. While the majority of identified B cell clones were restricted to a single site, many were disseminated in multiple sites. Members of a clone were shared more between adjacent biopsies than between distal biopsies, suggesting local mucosal migration and/or a homing mechanism for B cells through the blood or lymph. A smaller fraction of clones spanned the bronchial mucosa and peripheral blood, suggesting ongoing trafficking between these compartments. The bronchial mucosal B cell repertoire in the asthmatic patient was geographically more variable but less diverse compared to that of the healthy subject, suggesting an ongoing, antigen-driven humoral immune response in atopic asthma. Whether this is a feature of atopy or disease status remains to be clarified in future studies. We observed a subset of highly mutated and antigen-selected IgD-only cells in the bronchial mucosa. These cells were found in relative high abundance in the asthmatic individual but also, albeit at lower abundance, in the healthy subject. This novel finding merits further exploration using a larger cohort of subjects

Detection and Quantitation of Total and Allergen-Specific IgE in the Bronchial Mucosa of Atopic and Non-Atopic Asthmatics

RationaleIgE is thought to play a role in asthma pathogenesis. We hypothesised that aeroallergen-specific IgE is detectable in the bronchial mucosa of asthmatics regardless of their conventional atopic status.MethodsAtopic (n=9) and non-atopic (n=8) asthmatics as well as non-atopic nonasthmatic controls (n=8) were recruited with informed consent according to an ethically approved protocol. Biopsies were collected at fibreoptic bronchoscopy along with venous blood serum samples. Total and allergen component specific IgE were measured using Phadia ImmunoCAP and ImmunoCAP- ISAC microarray respectively in the sera and biopsy homogenates.ResultsIgE was detectable in the serum and bronchial mucosal homogenates in all groups. The median serum total IgE concentration was significantly elevated in the atopic, but not the non-atopic asthmatics as compared with the non-atopic nonasthmatics. In contrast, the median total IgE concentration in the biopsy homogenates was significantly higher in the non-atopic, but not the atopic asthmatics compared with the controls. Allergen component-specific IgE species were not detectable by ISAC in the sera or biopsy homogenates of the non-atopic asthmatics and controls. Allergen component-specific IgE species were detectable in the sera and biopsy homogenates of the atopic asthmatics. The relative concentrations of some of these components were higher in the mucosa than in the serum.ConclusionsIt is possible to extract and characterise IgE from bronchial mucosal biopsies. IgE is detectable in the bronchial mucosa of non-atopic asthmatics but is not directed against a wide range of common aeroallergen components. The specificities and functional activities of these IgE species remain to be investigated

“Auto-anti-IgE”: Naturally occurring IgG anti-IgE antibodies may inhibit allergen-induced basophil activation

BackgroundNaturally occurring IgE-specific IgG autoantibodies have been identified in patients with asthma and other diseases, but their spectrum of functions is poorly understood.ObjectiveAddress the hypothesis that: (i) IgG anti-IgE autoantibodies are detectable in the serum of all subjects but elevated in asthmatic patients regardless of atopic status as compared with controls; (ii) some activate IgE-sensitized basophils; and (iii) some inhibit allergen-induced basophil activation.MethodsIgE-specific IgG autoantibodies were detected and quantified in sera using ELISA. Sera were examined for their ability to activate IgE-sensitized human blood basophils in the presence and absence of allergen using a basophil activation test, and to inhibit allergen binding to specific IgE on a rat basophilic cell line stably expressing human FcεRI.ResultsIgG autoantibodies binding to both free and FcεRI-bound IgE were detected in patients with atopic and non-atopic asthma, as well as controls. While some were able to activate IgE-sensitised basophils, others inhibited allergen-induced basophil activation, at least partly by inhibiting binding of IgE to specific allergen.ConclusionNaturally occurring IgG anti-IgE autoantibodies may inhibit, as well as induce, basophil activation. They act in a manner distinct from therapeutic IgG anti-IgE antibodies such as omalizumab. They may at least partly explain why atopic subjects who make allergen-specific IgE never develop clinical symptoms, and why omalizumab therapy is of variable clinical benefit in severe atopic asthma

B Cell Mobilization, Dissemination, Fine Tuning of Local Antigen Specificity and Isotype Selection in Asthma

In order to better understand how the immune system interacts with environmental triggers to produce organ-specific disease, we here address the hypothesis that B and plasma cells are free to migrate through the mucosal surfaces of the upper and lower respiratory tracts, and that their total antibody repertoire is modified in a common respiratory tract disease, in this case atopic asthma. Using Adaptive Immune Receptor Repertoire sequencing (AIRR-seq) we have catalogued the antibody repertoires of B cell clones retrieved near contemporaneously from multiple sites in the upper and lower respiratory tract mucosa of adult volunteers with atopic asthma and non-atopic controls and traced their migration. We show that the lower and upper respiratory tracts are immunologically connected, with trafficking of B cells directionally biased from the upper to the lower respiratory tract and points of selection when migrating from the nasal mucosa and into the bronchial mucosa. The repertoires are characterized by both IgD-only B cells and others undergoing class switch recombination, with restriction of the antibody repertoire distinct in asthmatics compared with controls. We conclude that B cells and plasma cells migrate freely throughout the respiratory tract and exhibit distinct antibody repertoires in health and disease