Plasma concentration of thymus and activation-regulated chemokine in childhood asthma

Background: Thymus and activation-regulated chemokine (TARC) is responsible for trafficking of T helper 2 lymphocytes into sites of allergic inflammation. However, its role in assessing the severity of acute asthma in children is still unclear. Objective: We sought to evaluate plasma TARC as a marker for monitoring asthma exacerbation in terms of asthma attack severity. Methods: Plasma TARC concentration was estimated in 24 asthmatic children aged between 2 and 17 years attending the Pediatric Allergy and Immunology Unit of Children’s Hospital, Ain Shams University, and 23 age and sex-matched healthy children using a sandwich enzyme immunoassay technique. For asthmatic patients, the measurement was performed during and after the resolution of acute asthma attack. In addition, complete hemogram and plasma total IgE were evaluated and peak expiratory flow rate was assessed in asthmatic patients during and after acute asthma exacerbation. Results: Plasma TARC mean concentration was significantly higher during acute asthma (839.2 ± 453.6 pg/ml) than after resolution of symptoms (416.5 ± 324.8 pg/ml) and both were statistically higher than the control value (165.7 ± 135.2 pg/ml). During acute attacks of asthma, plasma TARC level was significantly elevated among patients with severe attacks of wheezing (1336.3 ± 431.2 pg/ml) than in those with moderate (743.8 ± 91.8 pg/ml) and mild (437.5 ± 66.1 pg/ml) attacks and inversely related to PEFR measurements during attacks (r = -98, P < 0.001). Meanwhile, no significant relationship was found between plasma TARC levels and either plasma total IgE levels or the absolute eosinophil count. Neither the history of other atopic symptoms nor family history of atopy influenced plasma TARC levels. A significant reduction in plasma TARC level was observed after treatment with inhaled ß2 agonist drugs either alone or in conjunction with inhaled glucocorticoids. Conclusion: Our findings support the concept that TARC may be implicated in the pathogenesis of asthma. Plasma TARC is a useful marker in monitoring the severity of asthma exacerbation and in assessing the degree of allergic inflammation in the asthmatic airway. This would help physicians to design appropriate therapy in terms of dose and duration of treatment especially among children with quiescent asthma. Future studies should focus on using TARC antagonists as a new approach to asthma immunotherapy.Keywords: bronchial asthma, acute attacks, remission, TARC, atopy, inhaled glucocorticoids, ß2 agonistsEgypt J Pediatr Allergy Immunol 2003; 1(2): 86-9