Asthma is considered a chronic inflammatory airway disease. Mounting evidence reports that patients with asthma are at significantly higher risk of developing communicable diseases such as invasive pneumococcal disease, Haemophilus influenza, varicella, measles, pertussis and tetanus. While impaired innate immunity may play a role in increased risk of developing these infections, suboptimal adaptive immune responses have also been reported to play a role in asthmatic subjects with regard to increased risk of infections. This review discusses the currently underrecognized immunological effect of asthma on antibody to vaccines and recommends that clinicians be aware of less optimal antibody production in response to vaccines in subjects with asthma.

Purpose: Vitamin D plays an important role in calcium homeostasis and bone metabolism. It is associated with various diseases such as cardiovascular, immune, allergic and infectious disease. The aim of this study was to investigate the difference in clinical manifestations according to the concentration of vitamin D in mild bronchiolitis. Methods: We performed a retrospective review of medical records of patients with mild bronchiolitis from November 2016 to April 2017 in Daegu Fatima Hospital. Mild bronchiolitis was classified by the modified Tal's score method. Patients were divided into 2 groups according to a 25-hydroxyvitamin D level of 20 ng/mL. We analyzed the clinical characteristics and laboratory data from the 2 groups. Results: Of the 64 patients, 19 were included in the deficiency group and 45 in the normal group. Vitamin D levels were $11.7{\pm}4.9ng/mL$ in the deficiency group and $28.8{\pm}5.0ng/mL$ in the normal group. There were no differences in clinical features between both groups. However, the vitamin D deficiency group had significantly longer hospitalization than the normal group ($6.78{\pm}2.74$ days vs. $5.3{\pm}1.7$ days, P=0.045). In the deficiency group, the incidence of previous respiratory diseases was significantly higher (P=0.001). No significant difference in blood and respiratory virus tests was observed. Conclusion: Low vitamin D levels in mild bronchiolitis were associated with longer hospitalization and prior respiratory disease. Vitamin D may affect the course of mild bronchiolitis.

Purpose: We evaluated the clinical features of croup in children according to viral etiology. Methods: This study enrolled pediatric patients with croup, who showed positive results on respiratory virus reverse transcriptase polymerase chain reaction performed between January 2012 and December 2017. We retrospectively reviewed the medical records. Results: A total of 179 patients (119 boys and 60 girls) were enrolled with the mean age of $18.9{\pm}14.7$ months. The viruses commonly identified were parainfluenza, respiratory syncytial virus, rhinovirus, and influenza. Among these 4 viruses, patients with rhinovirus infection showed significantly shorter fever and admission durations. Patients with parainfluenza infection showed significantly lower incidences of epinephrine nebulization and patients with influenza infections showed significantly higher incidences of steroid treatment. Conclusion: Clinical manifestations of croup differ according to causative viruses. Further studies should be conducted to evaluate the severity and prognosis of croup according to viral etiology.

Purpose: It is thought that Mycoplasma pneumoniae infection is more prevalent and causes more severe pneumonia in school-age children and young adults than in preschool children; however, recent studies suggest that the infection may be underdiagnosed and more severe in preschool children. This study investigated the clinical characteristics of Mycoplasma pneumoniae pneumonia (MPP) and the risk factors of refractory MPP (RMPP) by age. Methods: We retrospectively reviewed the medical records of 353 children admitted due to MPP from January 2015 to December 2016. Demographics, clinical information, laboratory data and radiological findings were collected from all patients in this study. The patients were divided into 2 groups by the age of 6 years. Also, both preschool (< 6 years old) and school-age (${\geq}6$ years old) children were divided into RMPP and non-RMPP patients. Results: Total febrile days, febrile days before admission and the duration of macrolide antibiotic therapy were significantly longer in school-age children than in preschool children. School-age children had significantly greater risk of lobar consolidation (P=0.036), pleural effusion (P=0.001) and extrapulmonary complications (P=0.019). Necrotizing pneumonia and bronchiolitis obliterans tended to occur more frequently in preschool children than in school-age children. In both preschool and school-age children, lactate dehydrogenase (LDH) levels were significantly higher in RMPP patients than in non-RMPP patients. In preschool children, LDH > 722 IU/L (odds ratio [OR], 3.02; 95% confidence interval [CI], 1.44-6.50) and ferritin > 177 ng/mL (OR, 5.38; 95% CI, 1.61-19.49) were significant risk factors for RMPP, while LDH > 645 IU/L (OR, 4.12; 95% CI, 1.64-10.97) and ferritin > 166 ng/mL (OR, 5.51; 95% CI, 1.59-22.32) were so in school-age children. Conclusion: Clinical features of MPP were significantly different between preschool and school-age children. LDH and ferritin may be significant factors of RMPP in preschool and school-age children.

Purpose: Foreign body aspiration in children is emergent and can cause serious complications. This study aims to show the clinical characteristics of foreign body aspiration and to analyze the clinical cases of delayed diagnosis to predict and prevent complications. Methods: We retrospectively reviewed the medical records of 63 children (48 in Inha University Hospital and 15 in Gachon University Gil Medical Center) who were diagnosed with foreign body aspiration through bronchoscopy from 1996 to 2017 in Incheon City, and analyzed clinical characteristics. Patients were divided into 3 groups: those were diagnosed within 24 hours, delayed after 24 hours, or delayed more than 7 days according to time elapse from the time of foreign body aspiration, and clinical characteristics of each group were compared. Results: Aspiration occurred in 58.7% at 1 year and 15.9% at 2 years. Cough (65.1%) and coarse breathing sound (41.3%) were most common, and radiologic findings were commonly presented as emphysema on the affected side (41.3%). Nuts were most common (42.9%), and there was no difference in the frequency between the right and left main bronchi. The documented history of foreign body aspiration was more frequently found in the early diagnosed group; however, sputum, fever, and complications were more frequent in the delayed diagnosed group. Conclusion: If a patient with respiratory disease has persistent fever or sputum, foreign body aspiration should be suspected.

Purpose: Conventional serum IgE assay was costly, required the skills of expert, and relied heavily on expensive equipment. Quantitative measurement of total IgE using Point of Care Test (POCT) device can be the solution for these limitations. This study evaluated and validated the reproducibility of ImmuneCheck IgE. Methods: This study included 120 patients of allergic diseases such as allergic rhinitis, asthma, drug allergy, food allergy, atopic dermatitis, or anaphylaxis. The reliability of POCT ImmuneCheck IgE was evaluated by comparing results from the naked eye and from the Q-Reader. Intratest reproducibility and intertest correlation were analyzed using intraclass correlation coefficient (ICC). Results: Of the 120 enrolled patients, 51 were males and 69 were females. The ages ranged from 19 to 84 years, with an average age of 51.5 years. The concentration of serum total IgE measured by Phadia ImmunoCAP IgE ranged from 5.95 to 5,000 IU/mL. ICC for Intratest reproducibility of ImmuneCheck IgE by naked eye and by Q-Reader were 0.991 (P< 0.001) and 0.989 (P< 0.001), respectively. In addition, intertest correlation between ImmuneCheck IgE and Phadia ImmunoCAP IgE results of naked eye and Q-Reader were 0.968 (P< 0.001) and 0.948 (P< 0.001), respectively. Conclusion: The ImmuneCheck IgE was reproducible and highly correlated with conventional Phadia ImmunoCAP IgE assay. This result suggests that ImmuneCheck IgE can be a useful tool for rapid and precise detection of total IgE.

Purpose: Radiocontrast media are widely used in medical imaging to improve diagnostic accuracy. However, studies on the adverse reactions of radiocontrast media in children are limited. We aimed to describe the characteristics of adverse reactions to radiocontrast media among children who had a computed tomography scan or magnetic resonance imaging in a tertiary university hospital. Methods: We retrospectively collected data on adverse reactions to radiocontrast media by the reporting system of a tertiary university hospital. We selected data from children under the age of 19 from July 2011 to December 2017 and analyzed their characteristics. We focused mainly on the characteristics of the index case which is defined by the first adverse event of each subject. Results: During the period, a total of 88,050 radiocontrast media-enhanced imaging studies were performed and 184 cases of adverse reactions were reported. A total of 71 were identified as index cases. Forty-nine (69.0%) were male and the mean age was $12.7{\pm}3.2$ years. The incidence of radiocontrast media-related adverse reactions was 0.09% and severe reactions were 0.002%. The most common clinical feature was skin manifestations (54.9%), followed by gastrointestinal symptoms (40.8%) and neuropsychiatric symptoms (7.4%). Conclusion: Adverse reactions to radiocontrast media rarely occur in children and the incidence of severe reactions is low. Most reactions are mild and are related to the skin and gastrointestinal system. This report would provide good evidence for establishing a management strategy in children scheduled for imaging studies using radiocontrast media.