Abstract: Objective To study the mechanism of the bro nchial hyperresponsiveness (BHR) in the active pulmonary tuberculosis patients.Methods 75 pulmonary tuberculosis cases and the normal persons in the control group were tested by the pulmonary function,T cell subclasses and histamine provocation test.Results The histamine provocation test positive rate were 16.0%,there were not a significant difference between the histamine provocat ion test positive and negative in T cell subclasses in peripheral blood (CD⁺₃70.7%±8.7% and 73.1%±9.1%、CD⁺₄32.1%±6.3% and 35.6%±4.8%、CD⁺₈43.5% ±7.7% and 41.9%±7.4%、CD⁺₄/CD⁺₈0.9%±0.1% and 1.0%±0.1%),but highert han normal in CD⁺₃ and CD⁺₈ (55.5%±6.3% and 25.7%±4.1%) and lower in CD⁺₄/CD⁺₈ (1.5%±0.2%)(P＜0.01).There were a significant difference in PMMF (provocation test positive group:53.6%±5.5%,negative group:67.8%±6.5%)( P＜0.01).Twelve positive subjects in pulmonary tuberculosis had ten cases PMMF<60%,while negative group were 19.1%,there were a significant difference (P＜0.01).The linear correlation showed,when PMMF decreasing,the dose of PD_20FEV1 decreasing,the degree of BHR increasing,pearson correlation coefficient was 0.86,P＜0.01 .Conclusion In the active pulmonary tuberculosis,the small airway narrow play a key role in the mechanism of BHR and there are not a obviousre lative to the cell mediated immunity.

Key words: Pulmonary,tuberculosis, BHR, Pulmonary function, T cell subclasses