BACKGROUND: It has been well known that bronchial asthma is a chronic inflammatory disorder. The "activation" of lymphocytes has a significant role in the pathogenesis of bronchial asthma. Among these lymphocytes, TH2-like rather than TH1-like lymphoytes are activated in the bronchial tissues from patients with atopic bronchial asthma. However, the difference of cytokines expression is not well documented between the atopic normal subjects and atopic asthmatics. METHODS: Bronchial tissues were obtained from the tweleve atopic and non-atpoic asthmatics and tweleve atopic and non-atopic healthy subjects for in stiu hybridizatin of IL-2, IL-4, IL-5, and INF-gamma. The probe of cytokines were tagged with digoxigenin by random priming method. RESULTS: The infiltration of many inflammatory cells on submucosa and denuded epithelium were observed in the bronchial tissue from patients with bronchial asthma. The RNase-treated bronchial tissues did not have the brown signal on the tissue, but, RNase-untreated bronchial tissues had the positive brown signal on the inflammatory cells under the basement membrane. The IL-2 positive signals were detected in 2 cases, IFN-gamma in 1 case, IL-4 in 2 cases, IL-5 in 2 cases among 6 non-atopic healthy subjects. The atopic healthy subjects showed 1 case of positive signal of IL-2 and IFN-gamma, but did not show any signals of IL-4 and IL-5. The positive signals of IL-2 were detected in 4 cases among 6 atopic and 6 non-atopic asthmatics, 2 cases and 1 case of IFN-gamma respectively, 4 cases and 3 cases of IL-4 respectively, 4 cases and 3 cases of IL-5 respectively. CONCLUSION: The lymphocytes were activated in the bronchus of asthmatics. Among lymphocytes, TH2-like lymphocytes may be involved in the pathogenesis of bronchial asthma. However, futher study with immunohistochemical stain may be necessary for defining the source of cytokines, because of TH2-like lymphocytes were also activated in some atopic healthy subjects.