Frequency of allergen-specific T lymphocytes in blood and bronchial response to allergen in asthma.

Abstract

This study was designed to investigate whether the bronchial response to the sensitizing allergen in asthma is correlated with the frequency of allergen-specific T lymphocytes. Twenty-three asthmatic patients sensitized to Dermatophagoides pteryonyssinus who had never received hyposensitizing therapy and 11 healthy control subjects were studied. Allergen-specific T lymphocytes were enumerated in peripheral blood with limiting dilution cultures. Bronchial challenge with methacholine was performed in all subjects; patients with asthma also underwent an allergen bronchial challenge. Correlations between allergen-specific T cell frequencies and nonspecific bronchial hyperresponsiveness to methacholine as independent variables and early and late bronchial responsiveness to allergen challenge as dependent variables were investigated by means of stepwise-multiple regression analysis. We found that the frequency of allergen-specific T lymphocytes was higher than in control subjects in both patients with asthma with (p < 0.001) and those without (p < 0.05) late-phase asthmatic response to allergen. Moreover, the provocative does of allergen necessary to produce an early 15% fall of forced expiratory volume in 1 second could be predicted in part (59%) by an equation that incorporates methacholine sensitivity and allergen-specific T cell frequency. We conclude that allergen-specific T lymphocytes, which have an established influence on immunoglobulin E production, play an additional role in the induction of the bronchospastic response to inhaled allergen.