BackgroundM. pneumoniae pneumonia (MP) has been reported in 10-40% of community-acquired pneumonia cases. We aimed to evaluate the difference of clinical features in children with MP, according to their age and chest radiographic patterns.MethodsThe diagnosis of MP was made by examinations at both admission and discharge and by two serologic tests: the indirect microparticle agglutinin assay (≥1:40) and the cold agglutinins titer (≥1:32). A total of 191 children with MP were grouped by age: ≤2 years of age (29 patients), 3-5 years of age (81 patients), and ≥6 years of age (81 patients). They were also grouped by pneumonia pattern: bronchopneumonia group (96 patients) and segmental/lobar pneumonia group (95 patients).ResultsEighty-six patients (45%) were seroconverters, and the others showed increased antibody titers during hospitalization. Among the three age groups, the oldest children showed the longest duration of fever, highest C-reactive protein (CRP) values, and the most severe pneumonia pattern. The patients with segmental/lobar pneumonia were older and had longer fever duration and lower white blood cell (WBC) and lymphocyte counts, compared with those with bronchopneumonia. The patient group with the most severe pulmonary lesions had the most prolonged fever, highest CRP, highest rate of seroconverters, and lowest lymphocyte counts. Thrombocytosis was observed in 8% of patients at admission, but in 33% of patients at discharge.ConclusionsIn MP, older children had more prolonged fever and more severe pulmonary lesions. The severity of pulmonary lesions was associated with the absence of diagnostic IgM antibodies at presentation and lymphocyte count. Short-term paired IgM serologic test may be mandatory for early and definitive diagnosis of MP.

Kawasaki disease (KD), a systemic vasculitis of infants and children, manifests as fever and mucocutaneous inflammation. Although its etiology is largely unknown, the epidemiological data suggest that genetic factors are important in KD susceptibility. To identify genetic variants influencing KD susceptibility, we performed a genome-wide association study (GWAS) and replication study using a total of 915 children with KD and 4553 controls in the Korean population. Six single-nucleotide polymorphisms (SNPs) in three loci were associated significantly with KD susceptibility (P<1.0 × 10), including the previously reported BLK locus (rs6993775, odds ratio (OR)=1.52, P=2.52 × 10). The other two loci were newly identified: NMNAT2 on chromosome 1q25.3 (rs2078087, OR=1.33, P=1.15 × 10) and the human leukocyte antigen (HLA) region on chromosome 6p21.3 (HLA-C, HLA-B, MICA and HCP5) (rs9380242, rs9378199, rs9266669 and rs6938467; OR=1.33-1.51, P=8.93 × 10 to 5.24 × 10). Additionally, SNP rs17280682 in NLRP14 was associated significantly with KD with a family history (18 cases vs 4553 controls, OR=6.76, P=5.46 × 10). These results provide new insights into the pathogenesis and pathophysiology of KD.

PurposeThe pathophysiology of hypogammaglobulinemia in nephrotic syndrome (NS) remains unknown. We evaluated the differences in the distribution of anti-bacterial antibodies and anti-viral antibodies, and those of immune antibodies and natural antibodies in steroid-sensitive NS.Materials and MethodsWe examined the antibody status of 18 children who had routine vaccinations. The levels of immnunoglobulin G (IgG), the IgG subclasses, and the antibodies induced by vaccinations such as diphtheria-pertussis-tetanus and measles-mumpsrubella were analyzed in children with steroid-sensitive NS.ResultsThere was a positive correlation between the albumin and IgG values (r = 0.6, p < 0.01), and the four IgG subclasses were all evenly depressed in the nephrotic children during the acute stage of the disease. The antibodies induced by bacterial antigens were depressed and the seropositivity of anti-viral antibodies tended to be lower than those of age-matched control children during the acute stage. The depressed immune antibody status recovered rapidly in the remission stage of NS, despite corticosteroid treatment.ConclusionsIgG levels correlated positively with albumin levels, and all antibodies, including immune and natural antibodies, were depressed in the acute stage of NS. Our results suggest that hypogammaglobulinaemia in NS may be associated with intravascular homeostasis of oncotic pressure.

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