Intracellular IL-5 expression by peripheral blood CD4[+] and CD8[+] T-cells in atopic and non-atopic asthma

ABSTRACT

There is evidence of CD8[+] and CD4[+] peripheral blood T cell activation in childhood atopic asthma. However, the immunopathology of non-atopic asthma in children remains unclear. We sought to investigate the intracellular IL-5 expression by peripheral blood CD4[+] and CD8[+] T cells in atopic and non-atopic asthmatic children in relation to asthma grading and severity of exacerbation, as well as is possible correlation to various inflammatory markers of asthma. The study comprised 35 atopic and 35 non-atopic asthmatic children enrolled during activity and 30 clinically healthy children. They were subjected to flow cytometric assessment of intracellular IL-5 expression in CD4[+] and CD8[+] T cell subsets as well as absolute eosinophil count, serum total IgE, eosinophil cationic protein [ECP], and urinary Leukotriene E4 [LTE4] estimation. Asthmatic children compiled all together and the atopic group showed highly significant increase in absolute eosinophil count, IgE% from high normal for age, serum ECP, urinary LTE4 / creatinine ratio, intracellular CD4[+] IL5, and CD8[+] IL5 T cell numbers as compared to the control group. Similar results were observed between the non-atopic asthmatic children and the control group. When the atopic and non-atopic asthmatic children were compared, the former group showed significantly higher values of all study parameters except the urinary LTE4, urinary creatinine ratio, and CD8[+] IL5 frequency. CD4[+] IL5 T cell number correlated positively with the absolute eosinophil count, IgE% and serum eosinophil cationic protein among the 70 asthmatic patients. Stepwise multi-regression analysis revealed CD4[+] IL-5 frequency to be an inverse independent variable for asthma exacerbation. Likewise, IL-5 production, either CD4[+] or CD8[+] T cells was an inverse independent variable for grading of asthma severity. Both CD8[+] and CD4[+] T cells contribute to the IL-5 production in asthmatic children whether atopic or non-atopic during disease activity. CD4[+] T cell IL-5 frequency estimation could be a useful marker for asthma exacerbation severity and both CD4[+] and CD8[+] T cell IL-5 frequencies might serve as markers for asthma grading