Selective IgA deficiency (SIgAD) is the most common human primary immune deficiency (PID). It is classified as a humoral PID characterized by isolated deficiency of IgA (less than 7 mg/dL but normal serum IgG and IgM) in subjects greater than 4 years of age. Intrinsic defects in the maturation of B cells and a perturbation of Th cells and/or cytokine signals have been hypothesized to contribute to SIgAD pathogenesis. The genetic basis of IgA deficiency remains to be clarified. Patients with SIgAD can be either asymptomatic or symptomatic with clinical manifestations including allergy, autoimmunity and recurrent infections mainly of the respiratory and gastrointestinal tract. Studies analyzing allergy on SIgAD patients showed prevalence up to 84%, supporting in most cases the relationship between sIgAD and allergic disease. However, the prevalence of allergic disorders may be influenced by various factors. Thus, the question of whether allergy is more common in SIgAD patients compared to healthy subjects remains to be defined. Different hypotheses support an increased susceptibility to allergy in subjects with SIgAD. Recurrent infections due to loss of secretory IgA might have a role in the pathogenesis of allergy, and vice versa. Perturbation of microbiota also plays a role. The aim of this review is to examine the association between SIgAD and atopic disease and to update readers on advances over time at this important interface between allergy and SIgAD.

Background: During the lockdown period caused by the SARS-CoV-2 pandemic, we monitored via online survey the trend of allergic symptoms and the therapeutic compliance in patients followed at our center. Material and methods: In June 2020, we selected children followed at the Allergy and Immunology Service of Umberto I Hospital, aged between 6 and 16 years old, diagnosed with asthma and/or rhinitis and sensitized to grass pollen or dust mite. We sent an email with 12 multiple-choice questions investigating several areas: type of disease and sensitization, recurrence of symptoms, medication use during lockdown compared to the same period of the previous year. Results: The results of 82 questionnaires showed that 17.8% of patients suffered from asthma, 24.4% from rhinitis, and 57.8% from both. Within the group of asthmatic children, most of them presented an improvement of their symptoms. Likewise, with regard to allergic rhinitis, most of them reported better clinical conditions. Regarding treatment, we observed a global decrease in the use of on-demand therapies (salbutamol, nasal corticosteroid, and antihistamine) for both pathologies. In addition, there was a reduction in the use of basal therapy for asthma and rhinitis from 2019 (23.3%) to 2020 (15.5%). Conclusions: Our data show a general trend of clinical improvement and a reduction in the use of on-demand and basal therapy in allergic children during the lockdown.

The prevalence of allergic diseases has dramatically increased among children in recent decades. These conditions significantly impact the quality of life of allergic children and their families. Lactoferrin, a multifunctional glycoprotein found in various biological fluids, is emerging as a promising immunomodulatory agent that can potentially alleviate allergic diseases in children. Lactoferrin’s multifaceted properties make it a compelling candidate for managing these conditions. Firstly, lactoferrin exhibits potent anti-inflammatory and antioxidant activities, which can mitigate the chronic inflammation characteristic of allergic diseases. Secondly, its iron-binding capabilities may help regulate the iron balance in allergic children, potentially influencing the severity of their symptoms. Lactoferrin also demonstrates antimicrobial properties, making it beneficial in preventing secondary infections often associated with respiratory allergies. Furthermore, its ability to modulate the immune response and regulate inflammatory pathways suggests its potential as an immune-balancing agent. This review of the current literature emphasises the need for further research to elucidate the precise roles of lactoferrin in allergic diseases. Harnessing the immunomodulatory potential of lactoferrin could provide a novel add-on approach to managing allergic diseases in children, offering hope for improved outcomes and an enhanced quality of life for paediatric patients and their families. As lactoferrin continues to capture the attention of researchers, its properties and diverse applications make it an intriguing subject of study with a rich history and a promising future.

Starting from the “Hygiene Hypothesis” to the “Microflora hypothesis” we provided an overview of the symbiotic and dynamic equilibrium between microbiota and the immune system, focusing on the role of dysbiosis in atopic march, particularly on allergic rhinitis. The advent of deep sequencing technologies and metabolomics allowed us to better characterize the microbiota diversity between individuals and body sites. Each body site, with its own specific environmental niches, shapes the microbiota conditioning colonization and its metabolic functionalities. The analysis of the metabolic pathways provides a mechanistic explanation of the remote mode of communication with systems, organs, and microflora of other body sites, including the ecosystem of the upper respiratory tract. This axis may have a role in the development of respiratory allergic disease. Notably, the microbiota is significant in the development and maintenance of barrier function; influences hematopoiesis and innate immunity; and shows its critical roles in Th1, Th2, and Treg production, which are necessary to maintain immunological balance and promote tolerance, taking part in every single step of the inflammatory cascade. These are microbial biotherapy foundations, starting from probiotics up to postbiotics and parabiotics, in a still-ongoing process. When considering the various determinants that can shape microbiota, there are several factors to consider: genetic factors, environment, mode of delivery, exposure to antibiotics, and other allergy-unrelated diseases. These factors hinder the engraftment of probiotic strains but may be upgradable with postbiotic and parabiotic administration directly on molecular targets. Supplementation with postbiotics and parabiotics could represent a very exciting perspective of treatment, bypassing probiotic limitations. At present, this avenue remains theoretical and to be explored, but it will certainly be a fascinating path to follow.

Cow’s milk protein allergy (CMPA) is the most common food allergy (FA) in infancy, affecting approximately 2% of children under 4 years of age. According to recent studies, the increasing prevalence of FAs can be associated with changes in composition and function of gut microbiota or “dysbiosis”. Gut microbiota regulation, mediated by probiotics, may modulate the systemic inflammatory and immune responses, influencing the development of allergies, with possible clinical benefits. This narrative review collects the actual evidence of probiotics’ efficacy in the management of pediatric CMPA, with a specific focus on the molecular mechanisms of action. Most studies included in this review have shown a beneficial effect of probiotics in CMPA patients, especially in terms of achieving tolerance and improving symptoms.

Background: Emerging evidence suggests that nutraceuticals, alongside standard therapy, may benefit children with allergic rhinitis (AR). This study aimed to compare the efficacy of Quertal^® (Neopharmed Gentili S.p.A., Milano, Italy), a nutraceutical supplement based on Perilla frutescens, Quercetin, and vitamin D3, combined antihistamines per os versus antihistamines alone, in improving AR symptoms considering respiratory functional and laboratory biomarkers in pediatric age. Materials and Method: This study included 100 children, 50 in the case group (Quertal^® plus antihistamines) and 50 in the control group (antihistamines alone), with mild/moderate AR sensitized to grass pollens. They underwent assessments of respiratory function (rhinomanometry-AAR, spirometry), inflammation markers (Nasal Nitric Oxide [nFeNO]; exhaled Nitric Oxide [eFeNO]; nasal cytology), and laboratory assays (blood eosinophils, total IgE and specific IgE to Phl p1). Results: After three months of treatment, the case group showed statistically significant improvement in nFeNO and eFeNO values compared to controls (p < 0.001), as well as a reduction in nasal eosinophils (p < 0.001). Conclusions: Adding Quertal^® to standard antihistamine therapy may reduce nasal inflammation and improve AR symptoms in pediatric patients. This combination therapy shows promise as a practical, well-tolerated approach to managing AR and may have broader implications for enhancing long-term outcomes.