The link between allergic conditions and common variable immunodeficiency (CVID) is still unclear. Only a few studies suggest allergic diseases are more prevalent in CVID patients than in the general population, and the role of IgE remains poorly defined. This study aims to evaluate the prevalence of allergic conditions in CVID and the role of serum IgE and IgA levels. This prospective, cross-sectional, case-control study enrolled Italian adult CVID patients to investigate allergic conditions' frequency and relationships between IgE, IgA, and clinical phenotypes. Analyses of diagnostic/prognostic accuracy were performed with ROC curves. We documented an allergic disease in 26.6% of 60 CVID patients, most commonly allergic rhinitis (56.2%) and bronchial asthma (12.5%). CVID patients with allergy had higher IgE levels (+8.9 kU/L, p = 0.006) than non-allergic ones, but lower than allergic individuals without CVID. IgE deficiency was observed in 65% of CVID patients, with a strong correlation between IgE and IgA levels (r = 0.7, p < 0.001). Low IgE (< 2.5 kU/L) and IgA levels (< 7 mg/dL) were significantly associated with lymphoproliferative (p < 0.001) and granulomatous phenotypes (p = 0.005), achieving an AUC of 94% and 81% for predicting lymphoproliferation and granulomatosis, respectively. The prevalence of allergic conditions in CVID patients is lower compared with previous studies. Low IgE levels served as a good biomarker for CVID and CVID-phenotypes. Combined serum IgE and IgA assessment improved prognostic stratification.

This narrative review synthesizes current evidence on the association between Celiac disease (CD) and pulmonary disorders, explores underlying mechanisms, and highlights clinical implications and future research directions. CD is a chronic autoimmune enteropathy triggered by gluten ingestion in genetically predisposed individuals. Although it primarily affects the small intestine, emerging evidence implicates extraintestinal involvement, particularly of the respiratory system, suggesting a potential gut-lung axis. This narrative review was conducted using PubMed, Scopus, and Web of Science, covering literature published in English up to October 2025. Search terms combined 'celiac disease' OR 'coeliac disease' with ('lung disease' OR 'pulmonary' OR 'respiratory tract' OR 'asthma' OR 'bronchiectasis' OR 'COPD' OR 'interstitial lung disease' OR 'pulmonary hemosiderosis'). Inclusion criteria were peer-reviewed human studies reporting pulmonary manifestations in celiac disease. Exclusion criteria included non-English language, in vitro or animal studies, abstracts without full text, and insufficient clinical or mechanistic data. This was not a systematic review, and therefore no PRISMA flow diagram was generated." Large-scale registry studies in Scandinavia and case-based evidence across Europe and Asia support a spectrum of pulmonary manifestations in celiac disease, ranging from asthma and chronic cough to rare but life-threatening idiopathic pulmonary hemosiderosis. Asthma and chronic cough were the most commonly observed associations, with population-based studies reporting an elevated risk. Case reports and small cohorts described co-occurrence with bronchiectasis and interstitial lung disease, while rare cases confirmed links to idiopathic pulmonary hemosiderosis (Lane-Hamilton syndrome). Proposed mechanisms include systemic immune activation, increased intestinal and pulmonary permeability, micronutrient deficiencies, IgA deficiency, and chronic inflammation. Notably, several studies reported symptom improvement or resolution following a gluten-free diet (GFD). Pulmonary manifestations of CD, though relatively uncommon, are clinically significant and often reversible with dietary intervention. Greater awareness, early recognition, and mechanistic research are essential to optimize patient outcomes.

IgA nephropathy (IgAN) is an autoimmune disease in which poorly galactosylated IgA1 is the antigen recognized by naturally occurring anti-glycan antibodies, leading to formation of nephritogenic circulating immune complexes. Incidence of IgAN displays geographical and racial disparity: common in Europe, North America, Australia, and east Asia, uncommon in African Americans, many Asian and South American countries, Australian Aborigines, and rare in central Africa. In analyses of sera and cells from White IgAN patients, healthy controls, and African Americans, IgAN patients exhibited substantial enrichment for IgA-expressing B cells infected with Epstein-Barr virus (EBV), leading to enhanced production of poorly galactosylated IgA1. Disparities in incidence of IgAN may reflect a previously disregarded difference in the maturation of the IgA system as related to the timing of EBV infection. Compared with populations with higher incidences of IgAN, African Americans, African Blacks, and Australian Aborigines are more frequently infected with EBV during the first 1-2 years of life at the time of naturally occurring IgA deficiency when IgA cells are less numerous than in late childhood or adolescence. Therefore, in very young children EBV enters "non-IgA" cells. Ensuing immune responses prevent infection of IgA B cells during later exposure to EBV at older ages. Our data implicate EBV-infected cells as the source of poorly galactosylated IgA1 in circulating immune complexes and glomerular deposits in patients with IgAN. Thus, temporal differences in EBV primo-infection as related to naturally delayed maturation of the IgA system may contribute to geographic and racial variations in incidence of IgAN.

The prevalence of coeliac disease (CD) in Vietnam is unknown. To fill this void, we assessed the prevalence of serological markers of CD autoimmunity in a population of children in Hanoi. The outpatient blood drawing laboratory of the largest paediatric hospital in North Vietnam was used for the study, which was part of an international project of collaboration between Italy and Vietnam. Children having blood drawn for any reason were included. Exclusion criteria were age younger than 2 years, acquired or congenital immune deficiency and inadequate sample. A total of 1961 children (96%) were enrolled (838 females, 1123 males, median age 5.3 years). Primary outcome was the prevalence of positive autoimmunity to both IgA antitransglutaminase antibodies (anti-tTG) assessed with an ELISA test and antiendomysial antibodies (EMA). Secondary outcome was the prevalence of CD predisposing human leucocyte antigens (HLA) (HLA DQ2/8) in the positive children and in a random group of samples negative for IgA anti-tTG. The IgA anti-tTG test was positive in 21/1961 (1%; 95% CI 0.61% to 1.53%); however, EMA antibodies were negative in all. HLA DQ2/8 was present in 7/21 (33%; 95% CI 14.5% to 56.9%) of the anti-tTG-positive children and in 72/275 (26%; 95% CI 21% to 32%) of those who were negative. Coeliac autoimmunity is rare in Vietnam, although prevalence of HLA DQ2/8 is similar to that of other countries. We hypothesise that the scarce exposure to gluten could be responsible for these findings.