Genetic variant of interleukin-13 [IL-13] and asthma in children

ABSTRACT

Interleukin-13 [IL-13] is a central cytokine in promoting asthma through the stimulation of bronchial epithelial mucus secretion and smooth muscle hyper reactivity. Genetic variants of IL-13 have an important role in the development of asthma in children. The aim of this study was to detect the association of "Gln110Arg" [a new variant of the human IL-13 gene] with asthma and to compare with its association with healthy children controls. The study was conducted at the Department of Pediatrics, El- Minia University Hospital, during the period from January 2002 to January 2003. The study included two groups of age matched children group I consisted of 35 asthmatic children [24 males and 11 females] with an age range from 2.1 to 8 years, and group II consisted of 15 apparent healthy children [7 males and 8 females] with an age range from 1.9 to 8.5 years as a control group. All children were selected from the followed up children and attendances of outpatient and inpatient of Department of Pediatrics, El-Minia University Hospital. Both patients and controls were subjected to clinical evaluation, complete blood count [CBC], pulmonary function tests, serum levels of total IgE and IL-13 performed by ELlSA technique, and PCR technique for detection of "Glnf10Arg" genetic variant of the human IL-13 gene on chromosome 5q31. The results showed that peripheral blood eosinophils [PBE] count, serum level of total IgE and serum level of IL-13 were significantly higher in asthmatic children compared with controls [p>0.0001, 0.0001,and 0,005 respectively]. There was no significant difference between PBE count and serum level of IL-13 in atopic and non-atopic asthmatic subgroups [p<0.3 and <0.3 respectively]. "Gln110Arg" variant was detected in 74.2% of asthmatic children and in 20% of the controls, with a statistically significant higher percentage in asthmatic children group [p<0.001]. There was no significant difference between the different clinical presentations in asthmatic children with positive "Gln110Arg" variant defection. There was no significant difference between the CBC including PBE count in asthmatic children with positive variant detection subgroup compared with those of negative variant detection subgroup. There was a significant higher serum level of IL-13 in asthmatic children with positive "Gln110Arg" variant detection subgroup than that in the asthmatic children with negative variant detection subgroup [p<0.002], while there was no significant difference of serum total IgE level in the two subgroups [p<0.2]