Interleukin-21 Receptor Gene Polymorphisms in Kawasaki Disease

BACKGROUND AND OBJECTIVES: Interleukin-21 receptor (IL-21R) gene polymorphism is related with the development of systemic vasculitis. In this study, we investigated the polymorphisms of IL-21R gene in patients with Kawasaki disease (KD). SUBJECTS AND METHODS: We genotyped the promoter region of IL-21R gene (-2500 bp to +1 bp) in 100 patients with KD and 100 healthy controls. All study subjects were Korean. We designed five pairs of primers and performed polymerase chain reaction (PCR) and direct sequencing. We analyzed whole promoter sequences of 200 individuals with comparison to reference sequences of IL-21R gene (NG_012222.1/NC_000016.9). RESULTS: We found five single nucleotide polymorphisms (SNPs) of which minor allele frequency (MAF) >0.01 in the promoter region of IL-21R gene. Those are -1681 G>T (chromosome site 27411802), -379 G>A (27413104), -332 G>C (27413151, rs2214537), -237 A>T (27413246), and -53 G>A (27413430). There is no significant difference in MAF of each SNP between patients with KD and healthy controls except -237 A>T. Twenty five patients with KD had more than 1 SNP in contrast to only seven healthy controls had. The patients with KD have significantly more IL-21R gene polymorphisms than controls (odds ratio: 3.0, 95% confidence interval: 1.6-5.6, p=0.0005). There was no significant correlation between IL-21R gene polymorphisms and the serum level of IL-21. The serum level of total IgE was not significantly correlated with the presence of IL-21R gene polymorphisms. CONCLUSION: Our data suggest that the genetic susceptibility profile for KD may include IL-21R gene.

Plasma Real Time-Quantitative Polymerase Chain Reaction of Epstein-Barr Virus in Immunocompetent Patients with Hepatitis / 대한소아소화기영양학회지

PURPOSE: Epstein-Barr virus (EBV) hepatitis is a usually asymptomatic and self-limiting disease in immunocompetent patients. However, the range of severity is wide, and the serological diagnosis is typically difficult until the convalescent phase. Thus, we examined the value of plasma EBV DNA real-time quantitative polymerase chain reaction (RT-qPCR) in EBV hepatitis for the timely diagnosis and the relationship between EBV viral load and clinical severity. METHODS: Sixty samples were confirmed as having EBV infection by RT-qPCR with the EBV BALF5 gene sequence. We examined the clinical characteristics of EBV hepatitis by reviewing medical records. RESULTS: The median total duration of fever was 8 days (range: 0-13 days). The mean peak value of aspartate aminotransferase (AST) was 241+/-214 U/L, and the mean peak value of alanine aminotransferase (ALT) was 298+/-312 U/L. There was no correlation between the serum levels of liver enzyme and plasma EBV DNA titer (p=0.1) or between median total duration of fever and EBV DNA titer (p=0.056). The median age of the EBV VCA IgM-negative group was lower compared with the EBV VCA IgM-positive group in EBV hepatitis (2 years vs. 6 years, p=0.0009). CONCLUSION: The severity of EBV hepatitis does not correlate with circulating EBV DNA load according to our data. Furthermore, we suggest that plasma EBV PCR may be valuable in young infants in whom the results of serology test for EBV infection commonly are negative.

Elevated Serum Levels of IL-21 in Kawasaki Disease

PURPOSE: The serum level of immunoglobulin (Ig)E has been reported to be elevated in patients with Kawasaki disease (KD). We investigated whether interleukin (IL)-21, rather than IL-4, could be related to elevated serum levels of IgE in KD. METHODS: Sera from 48 patients with KD and 12 controls with high fever were collected to determine the level of IgE using an immunoassay system and the levels of IL-4 and IL-21 were determined using enzyme-linked immunosorbent assay kits. RESULTS: The median IL-21 level of KD patients was significantly elevated, at 499.5 pg/mL (range: <62.5-1,544 pg/mL), whereas that of controls was <62.5 pg/mL (<62.5-825 pg/mL; P<0.001). The median IL-4 level of KD patients was not elevated (4.0 pg/mL; 2.1-7.6 pg/mL). The median level of total IgE in KD patients was 58.0 IU/mL (5-1,109 IU/mL). No statistically significant correlation was found between IL-21 and total IgE levels (Spearman's R=0.2; P=0.19). CONCLUSIONS: Patients with KD have elevated levels of IL-21 in the serum. IL-21 may play a role in the pathogenesis of KD.