In childhood asthma the degree of allergen-induced T-lymphocyte proliferation is related to serum IgE levels and to blood eosinophilia

Objective: To investigate whether the state of activation of circulating T-cells in childhood asthma could be related to serum IgE levels and/or to blood eosinophilia. Methods: Seventeen atopic asthmatic children, sensitized to Dermatophagoides pteronyssinus .(Der p), in stable condition at the time of the study and 15 sex-matched and age-matched controls were studied. The expression of activation surface markers (HLA-DR and CD25) on peripheral blood mononuclear cells (PBMCs) was tested by monoclonal antibodies and FACS analysis, while the PBMC proliferative response to Der p antigens was measured by tritiated thymidine (³HTdR) incorporation. Results: As compared to controls, atopic children showed higher eosinophil counts (P <.01), similar lymphocyte counts (P >. 1, each comparison) but higher proportion of HLA-DR + and CD25 + T-lymphocytes (P <.05, each comparison). A significant Der p allergen-induced PBMC proliferation was observed in atopic children (P <.01) but not in controls (P > .1). Both in controls and in atopic children, no correlations were found between lymphocyte counts and eosinophil counts or total or allergen-specific IgE levels (P >. 1, each comparison). In contrast, weak correlations were detected between the degree of allergen-induced PBMC proliferation and: a) allergen-specific IgE levels in serum (P <.05) and b) eosinophil counts (P <.05). Conclusion: These data support the concept that the degree of activation of allergen-specific T-lymphocytes in blood may reflect the intensity of allergic sensitization in childhood asthma.