Increased expression of T- cell- surface CXCR4 in asthmatic children

Abstract

Background: Signals delivered through the chemokine receptor CXCR4 upon interaction with its ligand, SDF-1 α/β result in the most efficacious chemoattraction of T lymphocytes to the asthmatic airways with the resultant lung inflammation and airway hyperresponsiveness. Objective: The extensive pharmacological and physiological evidence that CXCR4 chemokine receptor influences the allergic airway disease has stimulated us to study the relation between its expression in peripheral blood T lymphocytes and the exacerbation of asthmatic attacks of varying severity. Methods: The chemokine receptor CXCR4 was assayed by flow cytometry in peripheral blood T lymphocytes from 25 asthmatic children, during asthma exacerbation and after complete remission of symptoms and physical signs. The results were compared to those of 30 healthy children. Results: The CXCR4 expression in peripheral blood T lymphocytes was significantly increased in children with acute exacerbations of bronchial asthma as compared to controls (mean ± SD = 62.27 ± 17.57% versus 24.76 ± 6.88%; p < 0.001). After remission of acute attacks, the CXCR4 expression decreased significantly as compared to the values during attacks (mean ± SD = 40.90 ± 13.25%), however, the level of expression during quiescence was still significantly higher than the values of the controls (mean ± SD = 40.90 ± 13.25%; p < 0.001). The CXCR4 expression was significantly higher in children with acute severe asthma as compared to those with either mild or moderate attacks. During remission, patients with mild intermittent asthma had less expression of CXCR4 when compared to any grade of persistent asthma, while the results were comparable between all groups of persistent asthma of varying severity. A significant positive correlation could link the CXCR4% to the absolute eosinophilic count during acute asthma attacks. Conclusion: CXCR4 is over-expressed in T lymphocytes of asthmatic children. It was found to be related to disease activity and seems to be involved in the establishment and maintenance of chronic inflammation of the airways.

Keywords: Asthma, chemokine receptors, CXCR4, children, T lymphocytes

Egypt J Pediatr Allergy Immunol 2003; 1(2): 80-5