Effects of BCG revaccination on asthma.

In a study conducted 1 year ago, we found that Th1 immune enhancement following Bacille Calmette-Guérin (BCG) vaccination effectively suppressed human asthma. To investigate whether revaccination would further improve lung function, BCG vaccine was given again. Current lung function tended to improve in the Repeated BCG group (n = 9), but not in the Single BCG group (previously the placebo group) (n = 11), compared with that 1 year ago. The BCG vaccination improved lung function in both groups, and the Repeated BCG group showed a significant increase in the peripheral blood interferon gamma/interleukin 4 ratio. These findings suggest that repeated BCG vaccinations might be effective in asthma therapy.