Association of the Expression of IL-4 and IL-13 Genes, IL-4 and IgE Serum Levels with Allergic Asthma

Immune and inflammatory responses mediated by cytokines, play important roles in the pathophysiology of asthma. These responses are associated with overexpression of Th2 cytokines such as IL-4 and IL-13. These two cytokines use common receptors for signaling that lead to identical immunological effects and regulation of the Th1/Th2 balance. The aim of this study was to determine whether patients with allergic asthma display overexpression of IL-4 and IL-13 genes. Using RT-PCR, we examined the expression of IL-4 and IL-13 genes in twenty asthmatic cases and twenty normal individuals. Total levels of serum IgE and IL-4 were also determined by ELISA method. Expression of IL-13 gene in 70% of patients with allergic asthma was higher than controls (P=0.01). There was no correlation between the expression of IL-13 gene and total level of serum IgE (P=0.07). Expression of IL-4 gene was detected in 30% of the patients and none of the normal individuals as determined by RT-PCR (P=0.01). Mean of serum IgE levels in patients and controls were 84.9 IU/ml and 62.2 IU/ml, respectively. Level of serum IgE was more than 100 IU/ml in 30% of patients (P=0.03). Mean of serum IL-4 levels in patients and controls were 15.73 pg/ml and 13.07 pg/ml, respectively. There was a relation between levels of serum IgE and IL-4 in 73% of cases. The results showed that there was a correlation between the expression of IL-4 gene and the level of serum IL-4. Levels of serum IgE and IL-4 were considerably higher in asthmatics than nonasthmatic controls.