Objective: To explore the preventive effect of BCG vaccine on asthma attack in rats and its relation with gamma delta T cells.
Methods: Wistar rats (n = 10, for each group) were immunized with BCG vaccine. After 8 weeks, the rats were sensitized and challenged with ovalbumin to establish an asthmatic model. After 3 weeks, the airway responsiveness (PC(50)) was determined. The percentage of gamma delta T cells or alpha beta T cells among total T cells or total lymphocytes and the ratio of the mean fluorescence density of CD(28)/gamma delta TCR of gamma delta T cell subset in peripheral blood and BALF were detected by flow cytometry, immunofluorescence and immunohistochemistry.
Results: In the rat asthmatic model, the number of BALF eosinophils was increased [(2.5 +/- 1.1) x 10(8)/L vs (0.0) x 10(8)/L], (P < 0.01). while the PC(50) was decreased [(0.28 +/- 0.10) g/L vs (1.36 +/- 0.76) g/L], (P < 0.01). However, the results of the group immunized with BCG vaccine were same as the controls [EOS (0.0) x 10(8)/L vs (0.0) x 10(8)/L], (P > 0.05). PC(50) [(1.28 +/- 0.77) g/L vs (1.36 +/- 0.76) g/L, (P > 0.05)]. In the asthmatic group, gamma delta T cell/T cell was (32.4 +/- 2.6)%, and gamma delta T cell/lymphocytes (28.6 +/- 2.4)%. In the group immunized with BCG vaccine, gamma delta T cell/T cell was (41.3 +/- 6.0)% and gamma delta T cell/lymphocytes (35.2 +/- 3.3)%. In the asthmatic group immunized with BCG vaccine, gamma delta T cell/T cell was (47.3 +/- 8.5)% and gamma delta T cell/lymphocytes (39.0 +/- 6.8)%. In the control group, gamma delta T cell/T cell was (27.3 +/- 0.8)% and gamma delta T cell/lymphocytes (21.8 +/- 1.9)%, (all P < 0.01). The ratio of the mean fluorescence density of CD(28)/gamma delta TCR of gamma delta T cell subset (0.66 +/- 0.08, 0.88 +/- 0.26, 0.71 +/- 0.15 vs 0.53 +/- 0.06, (all P < 0.01) were increased.
Conclusions: BCG vaccine was shown to be able to prevent the production of a rat asthmatic model. gamma delta T cells may also have a Th1/Th2 profile, and these cells may be important in the immunoregulation of BCG vaccine and the pathogenesis of asthma.