A rare IL33 loss-of-function mutation reduces blood eosinophil counts and protects from asthma.

IL-33 is a tissue-derived cytokine that induces and amplifies eosinophilic inflammation and has emerged as a promising new drug target for asthma and allergic disease. Common variants at IL33 and IL1RL1, encoding the IL-33 receptor ST2, associate with eosinophil counts and asthma. Through whole-genome sequencing and imputation into the Icelandic population, we found a rare variant in IL33 (NM_001199640:exon7:c.487-1G>C (rs146597587-C), allele frequency = 0.65%) that disrupts a canonical splice acceptor site before the last coding exon. It is also found at low frequency in European populations. rs146597587-C associates with lower eosinophil counts (ß = -0.21 SD, P = 2.5×10-16, N = 103,104), and reduced risk of asthma in Europeans (OR = 0.47; 95%CI: 0.32, 0.70, P = 1.8×10-4, N cases = 6,465, N controls = 302,977). Heterozygotes have about 40% lower total IL33 mRNA expression than non-carriers and allele-specific analysis based on RNA sequencing and phased genotypes shows that only 20% of the total expression is from the mutated chromosome. In half of those transcripts the mutation causes retention of the last intron, predicted to result in a premature stop codon that leads to truncation of 66 amino acids. The truncated IL-33 has normal intracellular localization but neither binds IL-33R/ST2 nor activates ST2-expressing cells. Together these data demonstrate that rs146597587-C is a loss of function mutation and support the hypothesis that IL-33 haploinsufficiency protects against asthma.

Immunogenicity and safety of a combined measles, mumps, rubella and varicella live vaccine (ProQuad ®) administered concomitantly with a booster dose of a hexavalent vaccine in 12-23-month-old infants.

BACKGROUND: Concomitant administration of vaccines can facilitate vaccination uptake, provided that no clinically significant effect on either vaccine is identified. We investigated the concomitant administration, during the second year of life, of one dose of the combined measles, mumps, rubella and varicella vaccine (ProQuad(®)) with a booster dose of a hexavalent vaccine. METHODS: In this multicentre, open-label study, participants were randomized to 3 groups: Group 1, concomitant administration of one dose of ProQuad(®) and a booster of hexavalent vaccine; Group 2, one dose of ProQuad(®) alone; Group 3, a booster dose of hexavalent vaccine alone. Two serum samples were collected, within 7 days prior to vaccination and Days 42-56 post-vaccination for antibody testing. RESULTS: Antibody response rates to measles, mumps, rubella, varicella, hepatitis B and Haemophilus influenzae type b following concomitant administration of ProQuad(®) and hexavalent vaccine were non-inferior compared with those following the individual vaccines. Antibody response rates to these antigens were all >95% in all groups. Antibody titres for the pertussis antigens following concomitant administration were also non-inferior to those following the individual vaccines. Antibody titres for the other valences were numerically comparable between groups with the exception of hepatitis B, Haemophilus influenzae type b, tetanus and poliomyelitis, which were higher in the concomitant than in the non-concomitant groups. The safety profiles of each vaccination regimen were comparable, with the exception of solicited ProQuad(®)-related injection-site reactions (Days 0-4), which occurred more frequently in the concomitant than in the non-concomitant groups. CONCLUSION: These immunogenicity data support the concomitant administration of ProQuad(®) with a hexavalent vaccine. The safety profile of concomitant ProQuad(®) and hexavalent vaccination was also in line with that of the individual Summaries of Product Characteristics.

Effect of rapid influenza testing on the clinical management of paediatric influenza.

BACKGROUND: Rapid tests are now widely available to assist the diagnosis of influenza; implementation may optimise the use of antiviral and antibiotic agents in the clinical management of influenza. OBJECTIVE: To explore the clinical management of children with influenza-like illness (ILI) when rapid influenza tests were and were not performed. METHODS: Between 15 January 2007 and 30 April 2007, a standardised questionnaire was used to record the clinical features of children aged 1-12 years who presented to office-based paediatricians in Germany with febrile ILI during periods of local influenza activity. For each paediatric contact, a clinical diagnosis of either 'influenza positive', 'influenza negative' or 'suspected ILI' was made. Where performed, the outcome of a Clearview Exact Influenza A + B rapid test was recorded. Prescriptions for antiviral agents and antibiotic medications were also recorded. RESULTS: A total of 16 907 questionnaires were evaluated. After fever (an entry criteria for all children), cough (84.6%), fatigue/decreased activity (83.0%), rhinorrhoea (73.7%) and headache (67.1%) were the most common symptoms. Influenza was clinically diagnosed in 56.8% (9596/16 907) of cases. The antiviral oseltamivir was prescribed for 24.6% (178/725) of children who were influenza positive by symptom assessment alone and 60.1% (4618/7685) of children who were influenza positive by rapid test. Antibiotics were less commonly prescribed for children who were influenza positive by rapid test [3.5% (271/7685) versus 17.2% (125/725) for symptom assessment alone]. CONCLUSIONS: In children with ILI, a positive rapid test result for influenza promotes the rational use of antiviral agents and reduces the inappropriate use of antibiotic medications.

Effect of variation in CHI3L1 on serum YKL-40 level, risk of asthma, and lung function.

BACKGROUND: The chitinase-like protein YKL-40 is involved in inflammation and tissue remodeling. We recently showed that serum YKL-40 levels were elevated in patients with asthma and were correlated with severity, thickening of the subepithelial basement membrane, and pulmonary function. We hypothesized that single-nucleotide polymorphisms (SNPs) that affect YKL-40 levels also influence asthma status and lung function. METHODS: We carried out a genomewide association study of serum YKL-40 levels in a founder population of European descent, the Hutterites, and then tested for an association between an implicated SNP and asthma and lung function. One associated variant was genotyped in a birth cohort at high risk for asthma, in which YKL-40 levels were measured from birth through 5 years of age, and in two populations of unrelated case patients of European descent with asthma and controls. RESULTS: A promoter SNP (-131C-->G) in CHI3L1, the chitinase 3-like 1 gene encoding YKL-40, was associated with elevated serum YKL-40 levels (P=1.1 x 10(-13)), asthma (P=0.047), bronchial hyperresponsiveness (P=0.002), and measures of pulmonary function (P=0.046 to 0.002) in the Hutterites. The same SNP could be used to predict the presence of asthma in the two case-control populations (combined P=1.2 x 10(-5)) and serum YKL-40 levels at birth (in cord-blood specimens) through 5 years of age in the birth cohort (P=8.9 x 10(-3) to 2.5 x 10(-4)). CONCLUSIONS: CHI3L1 is a susceptibility gene for asthma, bronchial hyperresponsiveness, and reduced lung function, and elevated circulating YKL-40 levels are a biomarker for asthma and decline in lung function.

Fine mapping and positional candidate studies on chromosome 5p13 identify multiple asthma susceptibility loci.

BACKGROUND: Genome-wide linkage scans to identify asthma susceptibility loci have revealed many linked regions, including a broad region on chromosome 5p. OBJECTIVE: To identify a 5p-linked asthma or bronchial hyperresponsiveness (BHR) locus. METHODS: We performed fine mapping and positional candidate studies of this region in the Hutterites and an outbred case-control sample from Germany by genotyping 89 single nucleotide polymorphisms (SNPs) in 22 genes. SNP and haplotype analyses were performed. RESULTS: Three genes in a distal region (zinc finger RNA binding protein [ZFR], natriuretic peptide receptor C, and a disintegrin and metalloproteinase domain with thrombospondin type 1 motif [ADAMTS12]) were associated with BHR, whereas 4 genes in a proximal region (prolactin receptor, IL-7 receptor [IL7R], leukemia inhibitory factor receptor [LIFR], and prostaglandin E4 receptor [PTGER4]) were associated with asthma symptoms in the Hutterites. Furthermore, nearly the entire original linkage signal in the Hutterites was generated by individuals who had the risk-associated alleles in ZFR3, natriuretic peptide receptor C, ADAMTS12, LIFR, and PTGER4. Variation in ADAMTS12, IL7R, and PTGER4 were also associated with asthma in the outbred Germans, and the frequencies of long-range haplotypes composed of SNPs at ZFR, ADAMTS12, IL7R, LIFR, and PTGER4 were significantly different between both the German and Hutterite cases and controls. There is little linkage disequilbrium between alleles in these 2 regions in either population. CONCLUSION: These results suggest that a broad region on 5p, separated by >9 Mb, harbors at least 2 and possibly 5 asthma or BHR susceptibility loci. These findings are consistent with the hypothesis that regions providing evidence for linkage in multiple populations may, in fact, house more than 1 susceptibility locus, as appears to be the case for the linked region on 5p. CLINICAL IMPLICATIONS: Identifying asthma or BHR genes could lead to novel therapeutic approaches.

Association study of Glutathione S-transferase P1 (GSTP1) with asthma and bronchial hyper-responsiveness in two German pediatric populations.

Glutathione S-Transferase P1 (GSTP1) is an important enzyme in the detoxification of products of oxidative stress. Several studies have shown an association of the amino acid variant Ile105Val with bronchial asthma and the reaction of the lung to inhalant pollutants. The aim of this study was to test the two known amino acid variants in GSTP1 for association with bronchial asthma and airway hyper-responsiveness in two German pediatric populations. We genotyped Ile105Val and Ala114Val in the Multicenter Allergy Study cohort (85 children with asthma, 123 controls) and asthmatic children from Freiburg (n = 178). We did not find association of either polymorphisms with bronchial asthma or airway hyper-responsiveness. We conclude from our data that polymorphisms within GSTP1 do not play a major role in the development of bronchial asthma in German children.

Polymorphisms and haplotypes of acid mammalian chitinase are associated with bronchial asthma.

RATIONALE: Chitinases are enzymes that cleave chitin, a polysaccharide contained in many parasites of humans. Recent studies in mouse models of bronchial asthma have shown that acid mammalian chitinase (AMCase) is involved in the pathophysiology of asthma. It acts downstream of interleukin-13; inhibition of AMCase leads to an abrogated T-helper cell 2 inflammation, less bronchial hyperreactivity, and fewer eosinophils. OBJECTIVES: The aim of this study was to identify common genetic variants in human AMCase and to use them to test for association of AMCase with pediatric asthma. METHODS: By sequencing the promotor region and all 11 exons on 30 individuals, 12 high-frequency polymorphisms were identified. Genotyping of six variants in exons and one promotor polymorphism was performed on the following populations by means of restriction fragment length polymorphisms: 322 children with asthma, 270 randomly chosen adult controls, and a pediatric control population consisting of 565 children who, at age 10 yr, had never wheezed and never been diagnosed having asthma. MEASUREMENTS AND MAIN RESULTS: We identified three known and two new amino acid variants. Analyses by the Armitage's trend test using both control populations showed association of the newly identified variant K17R and the nearby noncoding polymorphism rs3818822 with asthma (p = 0.0031 and p = 0.0003, respectively). In addition, haplotype analyses revealed strong association of haplotypes with the disease (asthma population vs. pediatric control subjects, p < 10(-10)). CONCLUSIONS: This newly described association between AMCase polymorphisms and asthma adds further evidence supporting the involvement of AMCase in the development of asthma.

Polymorphisms of the TGF-beta1 gene are not associated with bronchial asthma in Caucasian children.

The chromosomal region 19q13 has been found in linkage to allergic diseases in several genome-wide linkage screens. One candidate gene within this region is the gene coding for TGF-beta1. Transforming growth factor (TGF)-beta acts as an anti-inflammatory cytokine suppressing allergic inflammation and hyper-reactivity. However, in ongoing inflammation of the lungs it can induce fibrosis and airway remodelling as seen in chronic asthma. Several polymorphisms within TGF-beta1 have been identified and one, -C509T, has been shown to be in association with elevated immunoglobulin E levels and severe bronchial asthma in different populations. However, other studies failed to confirm the association. The present study investigated two polymorphisms within the gene coding for TGF-beta1, -C509T and G915C, and for their potential association with bronchial asthma in Caucasian children. Genotyping of these polymorphisms was performed by means of restriction fragment length polymorphisms in a population of 231 asthmatic children and a control population of 269 individuals. Statistical analyses made use of the Armitage's trend test. In addition haplotypes were calculated by arlequin. None of the two polymorphisms showed association with bronchial asthma. They were found to be in linkage disequilibrium. We conclude from our data that TGF-beta1 is unlikely to represent a major gene in the development of bronchial asthma in the Caucasian population.

Association study suggests opposite effects of polymorphisms within IL8 on bronchial asthma and respiratory syncytial virus bronchiolitis.

BACKGROUND: IL-8 is a strong inductor of inflammation. Accordingly, it plays a pivotal role in acute inflammatory responses during respiratory syncytial virus (RSV) infections and in chronic inflammatory diseases such as bronchial asthma and juvenile idiopathic arthritis. Recently, 2 studies have found association of the polymorphism -251A of IL8 with RSV bronchiolitis. Furthermore, epidemiologic studies have demonstrated an increased risk for the development of asthma after RSV bronchiolitis, and a common genetic background for the 2 diseases is currently being discussed. OBJECTIVE: This study investigated whether IL-8 is in association with asthma and/or arthritis and whether the results can confirm a common genetic background of RSV bronchiolitis and asthma. METHODS: The polymorphisms -A251T, C781T, C1633T, and A2767T within IL8 were genotyped in the following 4 populations: children with asthma, atopic children, children with juvenile idiopathic arthritis, and control subjects. Statistical analysis made use of the Armitage trend test and the software program Arlequine. RESULTS: Association of all polymorphisms was found with asthma ( P =.008 to P =.03). Surprisingly -251T was associated with asthma, which is the opposite allele as described in association with RSV bronchiolitis. Furthermore, all polymorphisms were significantly more common in children with arthritis than in asthmatic children ( P =.006 to P =.02). No association was seen with the diagnosis of arthritis per se or with atopy. CONCLUSION: This is the first study to describe association of IL-8 with asthma and a significant inverse distribution of the polymorphisms in juvenile idiopathic arthritis. In addition, the results of this study might suggest that RSV bronchiolitis and bronchial asthma have at least some different genetic factors.

Multilocus haplotype analyses reveal association between 5 novel IL-15 polymorphisms and asthma.

BACKGROUND: IL-15 is a T(H)1-related cytokine that is involved in the inflammatory response in various infectious and autoimmune diseases. IL-15 has recently been shown to be upregulated in T-cell-mediated inflammatory disorders. The observations suggest a potential role for this cytokine in a variety of pathologic conditions, including T(H)1-mediated and T(H)2-mediated inflammatory diseases. OBJECTIVE: In this study, we searched for single nucleotide polymorphisms in the whole IL-15 gene and investigated their association with inflammatory and/or atopic phenotypes. METHODS: The screening for single nucleotide polymorphisms was performed by single-strand conformation polymorphism analysis. Genotyping of the identified polymorphisms was performed by restriction fragment length polymorphism. Genotypic association analysis used the Armitage trend test. Haplotype frequency estimation and subsequent testing for differences between cases and controls were performed by using the programs FASTEHPLUS and FAMHAP. RESULTS: We identified 5 novel noncoding nucleotide sequence variants, all of which were typed in our asthmatic, our atopic, and our control population. According to the Armitage trend test, none of the 5 polymorphisms is associated with the phenotype bronchial asthma or atopy. However, multilocus haplotype analysis based on simulations to find out whether the haplotype frequencies differed between cases and controls by using the program FAMHAP yielded a P value of 6.1 x 10(-5) in the asthmatic versus the control population, which is highly significant. Furthermore, we obtained a nominally significant result of P=.0232 for the atopic versus the control population by using FAMHAP. CONCLUSION: These results strongly underscore previous findings that suggest a potential role of this cytokine in allergic diseases.

Association study of the IL13 variant Arg110Gln in atopic diseases and juvenile idiopathic arthritis.

BACKGROUND: It has previously been shown that various inflammatory diseases, such as diabetes mellitus, bronchial asthma, chronic inflammatory bowel diseases, and rheumatoid arthritis, are in some circumstances genetically linked to the same chromosomal regions. Consequently, common genes underlying the pathogenetics of these diseases have been proposed. Chronic inflammatory disorders can be subdivided by their predominant immune response, either TH1 or TH2. For example, juvenile idiopathic arthritis (JIA) is a TH1 disease, and bronchial asthma is a TH2 disease. OBJECTIVES: The present study investigated the polymorphism Arg110Gln within the IL13 gene, a strong TH2 cytokine. We attempted to determine whether it is associated with these 2 diseases and whether this would reflect the TH1/TH2 paradigm. METHODS: Arg110Gln was typed in 4 different populations: asthmatic children, atopic children, children with JIA, and a control population. Statistical analysis was performed by using logistic and linear regression analysis of serum IgE levels and the Armitage trend test. RESULTS: The variant Gln110 was shown to be associated with increased total serum IgE levels in our atopic population (P =.006) and was weakly associated with bronchial asthma (P =.04). There was no association of the variant with JIA when compared with the control population. However, the variant Gln110 was significantly less frequent in children with JIA compared with its presence in children with bronchial asthma (P =.007). CONCLUSION: This is the first study to compare the same gene variant in TH1 and TH2 chronic inflammatory diseases. The results suggest that the same gene variant might protect from one disease and make an individual susceptible to the other.

Association of uteroglobulin-related protein 1 with bronchial asthma.

BACKGROUND: Chromosomal region 5q31 harbours a number of genes associated with atopic phenotypes, for example the genes coding for interleukin (IL) 4, IL13 and the beta(2)-adrenoreceptor. A new gene within this region was identified only very recently. The encoded protein - uteroglobin-related protein 1 (UGRP1) - is thought to act as an anti-inflammatory agent and is mainly expressed in the lung and trachea. The functional promoter polymorphism A-112G in UGRP1 was shown to be associated with bronchial asthma in a Japanese population. We were thus interested in finding out whether the polymorphism so far identified or others within UGRP1 were associated with bronchial asthma in a German Caucasian population. METHODS: We performed direct genomic sequencing of the promoter and coding region of UGRP1 in 15 asthmatic children and 15 controls. The identified polymorphisms were genotyped by means of RFLP. Statistical analysis was performed with the Armitage trend test. RESULTS: We identified 5 non-coding variants, 4 of which being described for the first time. Three polymorphisms were common and typed in 182 asthmatic children and 270 controls. None of the polymorphisms were associated with bronchial asthma in our population. CONCLUSIONS: We conclude from our data that UGRP1 does not play a major role in the development of bronchial asthma in our Caucasian population.

Polymorphisms in the IL 18 gene are associated with specific sensitization to common allergens and allergic rhinitis.

BACKGROUND: Atopy has been linked to chromosome 11q22, a region that harbors the IL18 gene. IL-18 enhances IL-4/IL-13 production and induces IgE production that is directly associated with the pathogenesis of atopic disorders. OBJECTIVE: We sought to investigate whether genetic abnormalities in the regulatory regions of the IL18 gene predispose, in part, to susceptibility to atopy. METHODS: Among a white population of 105 families, the oldest child was examined with regard to atopic phenotypes and single-nucleotide polymorphisms (SNPs) within the IL18 gene. RESULTS: We have identified 5 novel SNPs in the IL18 gene (-920[t/c], -133[c/g], and -132[a/g] in promoter 2 [upstream of exon 2]; +179[c/a; Ser35Ser] in exon 4; and +486[c/t; Phe137Phe] in exon 6). Three SNPs are located in promoter 2, and one (-133[c/g]; nuclear factor 1 site) was significantly associated with high serum IgE levels (P =.001; odds ratio, 3.96) and specific sensitization to common allergens (P =.005; OR, 4.12). In addition, previously identified SNPs in exon 1 (+113[t/g] and +127[c/t]) and in promoter 1 (-137[g/c], GATA3 site) of the IL18 gene were significantly associated with high IgE levels (P < or =.005; OR, 3.27-3.90) and specific sensitization (P =.02 to.008; OR, 3.27-3.83). The SNP +127(g/t) in exon 1 was also a susceptibility locus for seasonal allergic rhinitis (P =.008; OR, 3.22). CONCLUSION: IL18 might be responsible for the linkage effects seen in the chromosomal region 11q22, which has been found previously with the phenotype "sensitization to mite allergen." Thus a suspected direct role of IL18 in the pathogenesis of atopy has been strengthened by the presence of 8 common SNPs in the promoter regions of IL18.

Dichotomic nature of atopic dermatitis reflected by combined analysis of monocyte immunophenotyping and single nucleotide polymorphisms of the interleukin-4/interleukin-13 receptor gene: the dichotomy of extrinsic and intrinsic atopic dermatitis.

Patients with atopic dermatitis display substantial immunologic abnormalities, among which elevated total IgE is considered as a hallmark; however, a subgroup of atopic dermatitis patients exhibits normal IgE levels, but mechanisms contributing to the so-called "intrinsic" or "nonallergic" form of atopic dermatitis are obscure. In order to unravel similarities and differences of both atopic dermatitis subtypes, the phenotype of monocytes, total serum IgE levels, and serum levels of cytokines regulating the IgE production from nonatopic individuals and patients with allergic rhinitis, and extrinsic and intrinsic atopic dermatitis were measured. Concomitantly, genomic DNA probes of all subjects were analyzed for single nucleotide polymorphisms of candidate genes of structures involved in the regulation of the IgE synthesis, such as interleukin-4 and the interleukin-4R/interleukin-13R. Our data show that the surface expression of the high- and low-affinity receptor for IgE (FcepsilonRI and FcepsilonRII/CD23) and the interleukin-4Ralpha chain were significantly elevated in monocytes from patients with extrinsic atopic dermatitis. Furthermore, serum levels of interleukin-13 were significantly increased in patients with intrinsic atopic dermatitis. In addition, the frequency of the interleukin-4Ralpha polymorphism C3223T and the interleukin-4 polymorphism C590T tended to be higher in extrinsic atopic dermatitis than in intrinsic atopic dermatitis. Altogether our findings indicate that intrinsic atopic dermatitis patients exhibit phenotypic and immunologic features, which differ from those of patients with extrinsic atopic dermatitis or other atopic disorders.

Distinct signal transduction processes by IL-4 and IL-13 and influences from the Q551R variant of the human IL-4 receptor alpha chain.

BACKGROUND: Although IL-4 and IL-13 share the IL-13 receptor, IL-13 exhibits unique functions. To elicit the cellular basis of these differences, signal transduction processes have been compared. Additionally, the role of the IL-4 receptor alpha (IL-4Ralpha) variant Q551R was investigated. METHODS: Peripheral blood mononuclear cells from donors were stimulated with IL-4 and IL-13. The phosphorylation status of effector substrates was detected by immunostaining. Binding of SHP-2 to IL-4Ralpha was investigated by using synthetic peptides. RESULTS: SHP-2 bound IL-4Ralpha synthetic peptide; this binding was reduced in the presence of the R551 variant. Stimulation with IL-4 increased SHP-1 phosphorylation, however, stimulation with IL-13 increased SHP-2 phosphorylation. PI3-kinase phosphorylation was elevated following stimulation with IL-13 in all individuals and with IL-4 only in R551 individuals. Jak1, Tyk2 and IRS-2 signals were reduced after IL-13 stimulation in Q551 individuals. STAT3 phosphorylation was markedly increased in R551 individuals, following stimulation with both IL-4 and IL-13. However, STAT3 was only detected immediately in nuclear extracts from variant individuals after stimulation with IL-13; in wildtype individuals STAT3 was only detected after IL-4 treatment. CONCLUSION: IL-4 and IL-13 appear to promote distinct signal transduction cascades. SHP-1 seems to be predominately activated by IL-4 and to influence the PI3-kinase, in contrast, SHP-2 seems to be predominately activated by IL-13 and to influence Jak1, Tyk2 and IRS-2. Both phosphatases control STAT3. In the presence of the variant R551, SHP-1/2 activation is reduced and signal transduction is altered. STAT3 signaling appears be further regulated on the level of nuclear translocation.

The variant Arg110Gln of human IL-13 is associated with an immunologically hyper-reactive form of onchocerciasis (sowda).

Onchocerca volvulus infection usually results in a predominantly immunopermissive reaction called generalized onchocerciasis and characterized by high microfilarial burden and immunological tolerance to the worms. Rarely, however, infection leads to the sowda form of the disease displaying low microfilarial numbers, i.e. microfilarial control, and a T helper 2 (Th2)-type immune response including high immunoglobulin (Ig)E levels, and interleukin (IL)-13 being one of the key cytokines. The aim of this study was to investigate a possible association of a variant of the IL-13 gene, which confers an IgE-independent risk for asthma and atopy, with the immunologically hyper-reactive sowda form of onchocerciasis. Genotyping for the IL-13 variant Arg110Gln revealed a highly significant association of Arg110Gln with the sowda form (relative risk of 2.98, n = 19 patients), whereas the frequency of the variant was significantly lower in patients with generalized onchocerciasis (n = 92 individuals). Sowda patients had higher IgE levels than those with generalized onchocerciasis. Logistic regression analysis revealed that IgE and IL-13 are independent variables, each increasing the relative risk for sowda. Arg110Gln has been suggested to lead to enhanced IL-13 signaling and thus may be involved in shifting the immune reaction towards the hyper-reactivity characteristic for the sowda form, thereby promoting defense mechanisms.