Lymphocyte activation by house dust allergen in asthma: analysis with monoclonal antibodies

Peripheral blood mononuclear cell (MNC) response to house dust (HD) stimulation in cultures was studied in a group of 35 subjects with asthma and a multiple positive skin test (ST) reaction to inhalant allergens including HD, and in 19 healthy controls. The MNC response to allergen stimulation was assessed by interleukin-2 receptor (IL-2R) expression identified with an anti-Tac monoclonal antibody. Lymphocyte subpopulations of baseline and cultured cells were also analysed. The percentage of IL-2R presenting cells increased significantly in HD-driven cultures in the asthma group compared to controls. The increase in proportion of IL-2R+ cells was closely related to the increase in CD4+ percentage of cultured cells and was accompanied by a decrease in proportion of CD8+ lymphocytes and monocytes/macrophages, suggesting that HD-activated cells were CD4+ lymphocytes. Lymphocyte activation, measured by IL-2R expression, was significantly higher in the group of asthmatics, and positive dual (early and late) skin reaction to HD, as compared to those with single early reaction.