[Activation of T lymphocytes and severity of atopic bronchial asthma in children]

Recent studies point out to the role of activated T lymphocytes in the pathogenesis of bronchial asthma. We analyzed (1) T subpopulations and (2) expression of the cell surface activation markers (the light chain of interleukin-2 receptor (IL-2R) and HLA-DR antigen) in the peripheral blood of 36 children with stable atopic asthma and 10 non-atopic control subjects. Flow cytometry and double phenotyping with monoclonal antibodies conjugated with fluorescein and phycoerythrin were used. The results of these studies were correlated to the degree of asthma severity. We found no differences between the two evaluated subgroups (severe asthma--AC and moderate asthma--AU) in the percentage of T cells with CD3 and CD4 antigen. In the severe asthma subgroup there were the following differences as compared with those from control subjects: decrease of the percentage of CD8+ lymphocytes (p < 0.01) and the increase of activated cells expressing IL-2R (p < 0.001) and HLA-DR (p < 0.001). Differences in the expression of activation markers were more pronounced in the CD4+ subpopulation (CD4+/IL-2R, p < 0.001 and CD4+/HLA-DR+, p < 0.001), while they were less visible, but still significant, in the CD8+ cells (CD8+/IL-2R+, p < 0.01 and CD8+/HLA-DR+, p < 0.05). When comparing the results in severe asthma subgroup with those in moderate asthma, significant elevation was found in CD4+/IL-2R+ (p < 0.03), CD4+/HLA-DR+ (p < 0.05) and CD8+/IL-2R+ (p < 0.03) double positive cells. These observations may indicate a role of activated T lymphocytes, CD4+ and CD8+, in the pathogenesis of atopic bronchial asthma in children and existence of prolonged activation factors in chronic severe asthma.