The hygiene hypothesis, first proposed in 1989, suggested that reduced exposure to infections in early life leads to allergic diseases by the defects in the establishment of immune tolerance. Although many studies provided evidence that some exposure conditions, including family size, antibiotics, probiotics, and viral or bacterial infections, are strongly related to the prevalence of allergic diseases, thereby supporting the hygiene hypothesis, some evidence does not provide acceptable results for the hygiene hypothesis. Further, most studies have focused on patients with asthma or atopic dermatitis, not allergic rhinitis. In this review, we summarize the recent studies for and against the 'hygiene hypothesis' and identify causal association with the prevalence of allergic rhinitis.

Wheat allergy is one of the common causes of food allergies in children. The prevalence varies by age and country, and is known to be 0.04%-0.97% globally and 0.2%-1.3% in Korea. Wheat allergy usually appears with skin symptoms within 2 hours after ingestion, and in severe cases, it causes systemic symptoms and anaphylaxis. Wheat-dependent exercise-induced anaphylaxis, a serious wheat allergy, may occur after wheat consumption along with cofactors, such as exercise, alcohol, aspirin and/or nonsteroidal anti-inflammatory drugs. Wheat allergy is confirmed by oral food challenge. However, the challenging test is difficult to perform, although it is a confirmative diagnostic method. With the development of component resolved diagnostics, ω-5 gliadin specific immunoglobulin E (sIgE) along with wheat sIgE are useful for diagnosis of it. Wheat allergy should be differentiated from oral mite anaphylaxis or cross-reactivity to grass pollen allergy. It is recommended to avoid foods containing wheat, however, recently, efforts are being made to improve quality of life with oral immunotherapy.

Purpose: Few meta-analyses of head-to-head comparisons between subcutaneous immunotherapy (SCIT) and sublingual immunotherapy (SLIT) for perennial allergic rhinitis (AR) have been performed so far. This study aimed to compare the efficacy, safety, and adherence of SCIT and SLIT in patients with house dust mite (HDM)-sensitized AR through a meta-analysis of head-to-head comparative studies. Methods: A meta-analysis based on direct comparisons of SCIT and SLIT in HDM-sensitized AR was performed, using randomized controlled trials (RCTs) and nonrandomized studies (NRSs), on efficacy, safety, and adherence, which had been published until April 30, 2021. Treatment efficacy was calculated as the standardized mean difference in symptoms and medication scores after treatment between SCIT and SLIT. Safety and adherence to treatment were compared with the relative risk (RR) of SCIT and SLIT. Results: Six RCTs and 3 NRS scores were analyzed. No statistically significant difference was noticed in improvement in symptoms and medication scores between SCIT and SLIT groups. Systemic adverse events occurred more frequently in SCIT than in SLIT in both RCT (RR, 3.97; 95% confidence interval [CI], 0.50-31.57) and NRS (RR, 5.48; 95% CI, 1.94-15.50). SCIT showed significantly higher adherence than did SLIT (RR, 1.16; 95% CI, 0.92-1.47). Conclusion: No significant difference in efficacy was noticed between the 2 modalities for HDM-sensitized AR. However, SLIT had significantly lower number of systemic adverse reactions, and SCIT had more preferable adherence.

Purpose: Eosinophils and total immunoglobulin (IgE) have served as a histologic hallmark of allergic conditions. Many investigators have used total eosinophil count (TEC) and total IgE for evaluating allergic diseases. We examined differences in TEC and total IgE in allergic diseases and whether it differs according to sensitization. Methods: In this retrospective study, we enrolled 551 patients who visited Uijeongbu St. Mary's Hospital from January 1, 2009 through December 31, 2012 for allergic diseases. We included patients with a diagnosis of atopic dermatitis (AD), allergic rhinitis (AR), asthma (AS), or urticaria (UC). We compared the TEC and total IgE level according to sensitization patterns. Results: There were 235 cases of AD, 179 cases of AS, 112 cases of AR, and 82 cases of UC. Regarding sensitization, 106 were not sensitized to any allergens, 206 were sensitized to inhalants, 109 were sensitized to food allergens, and 49 were sensitized to both food and inhalant allergens. TEC was significantly higher in the AD and AR group than in the UC group. TEC was significantly higher in those sensitized to both inhalant and food than those not sensitized. The total IgE levels were significantly higher in those sensitized to both inhalant and food than those not sensitized or sensitized to food. Total IgE levels were significantly higher in those sensitized to inhalant than those not sensitized or sensitized to food. Conclusion: Eosinophils appear to play differential roles in the expression of different types of allergic diseases. Total IgE level may play a significant role in sensitization.

We experienced a rare case of a 6-year-old boy who was suspected of having lipid transfer protein (LTP) syndrome; the patient was diagnosed with LTP syndrome using the ImmunoCAP/ImmunoCAP Immuno Solid-phase Allergen Chip (ISAC) test. LTP syndrome affects patients who are already sensitized to pollens with signs and symptoms of allergic rhinitis with or without bronchial asthma. Its severity is closely associated with the geographical location as well as the level, nature, and duration of the allergen exposure in a susceptible individual with or without cofactors, such as exercise, alcohol, chemicals, or nonsteroidal anti-inflammatory drug. Patients with LTP syndrome may present with diverse manifestations ranging from local symptoms, such as mild contact urticaria, oral allergy syndrome, or gastrointestinal problems, to anaphylaxis and even anaphylactic shock. Our case highlights the usefulness of the ImmunoCAP/ImmunoCAP ISAC test in establishing a diagnosis of LTP syndrome.

Allergy to crickets is uncommon and usually reported from workers who breed, manufacture, or consume them as food for either pets or for themselves. Although there are several reports of hypersensitivity reactions to crickets in other countries, there has been few published reports in this country. Here we report a case of a 20-year-old Korean male who had been exposed for a year in his workplace and developed occupational asthma and rhinitis sensitized to Gryllus bimaculatus (GB). The patient developed respiratory and cutaneous symptoms whenever he was exposed to or came into contact with GBs or dust from the cage storing the GBs. To identify the causative allergen in his workplace, soluble GB extracts were prepared with phosphate-buffered saline and was used for skin prick test (SPT) and immunologic studies. The patient showed positive results to GB extracts as well as to house dust mite (HDM) on SPT, while negative responses were noted in 3 unexposed controls. Higher level of serum GB-specific IgE by enzyme-linked immunosorbent assay (ELISA) was noted in the patient compared to those of 18 unexposed controls. The IgE-ELISA Inhibition test showed significant inhibitions with serial additions of GB extracts without any inhibitions with HDM extracts. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis and IgE-immunoblot analysis demonstrated several IgE binding components (range, 60-75 kDa). The patient was asked to avoid cricket exposure, and symptoms improved with the application of inhaled corticosteroids. Herein, we report a case of occupational asthma and rhinitis due to GB in an exposed worker.

Laryngomalacia, the most common cause of stridor in infants, is characterized by the inward collapse of soft and immature upper laryngeal cartilages during inspiration, resulting in airway obstruction at the supraglottic level. Acquired laryngomalacia is a rare condition that mainly occurs following significant neurological dysfunctions associated with cerebrovascular disease, head and neck surgery, or cervical trauma. We present a case of acquired idiopathic laryngomalacia in a 12-year-old adolescent caused by the prolapse of redundant arytenoid mucosa. The patient exhibited no neurological dysfunctions or laryngeal deformities. However, he had allergic rhinitis accompanied by high serum immunoglobulin E levels. His symptoms worsened after being infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Furthermore, allergic rhinitis or SARS-CoV-2 infection may have worsened preexisting asymptomatic congenital or acquired laryngomalacia through neurological damage. Acquired idiopathic laryngomalacia is rale in children. In cases where children and adolescents present with a sudden onset of inspiratory stridor, it is essential to perform a laryngoscopic examination for identifying potential cases of acquired laryngomalacia.