ABSTRACT
The incidence, morbidity and mortality of bronchial asthma have increased over the last two decades. Immune and inflammatory responses mediated by cytokines are essential in the pathophysiology of bronchial asthma. Substantial evidence has implicated Th2 cytokines, IL-4 and IL-5, in the pathology of allergic asthma and demonstrated protective effects of Th1 cells. This work was conducted to study the serum levels of IL-4, IL-5, IL-12 and IL-18, in patients with allergic asthma associated with eosinophilia. Interleukins levels were correlated with IgE level and the degree of eosinophilia in these patients. The study included 25 asthmatic patients with acute attack of bronchial asthma, associated with history of allergy and eosinophilia; and 25 normal healthy controls. All patients and controls were subjected to full medical history, clinical examination, and laboratory investigations for assessment of the eosinophil count and measurement of serum levels of IgE and interleukins [IL-4, IL-5, IL-12 and IL-18]. The correlation between interleukin [IL] levels, and degree of eosinophilia and IgE levels were also examined in these patients. Measurement of serum levels of interleukins showed significant elevation of IL-4, IL-5 and IL-18 levels in asthmatic patients as compared with the control group [p<0.0001], whereas IL-12 levels did not show any significant change [p>0.05]. Marked elevation in the IgE level and eosinophil count were also detected in asthmatic patients as compared with the control group [p<0.0001]. Significant positive correlations were observed between serum levels of IL-4, IL-5 and IL-18 and the degree of eosinophilia in asthmatic patients. A significant positive correlation was also detected between level of IL-18 and the IgE level in asthmatic patients. Patients with allergic bronchial asthma have elevated levels of IL-4, IL-5 as well as IL-18; and these levels correlated significantly with degree of eosinophilia in these patients. Further studies are needed to clarify the signaling cascade involved in allergic responses mediated by these ILs. This may help in developing new therapeutic modalities, as blockade of IL receptors, for these conditions