Tuberculosis vaccine: diabetes defense?

The BCG vaccine, used against tuberculosis for more than 50 years, may still have a few tricks up its sleeve. In initial tests, a single dose suppressed the development of diabetes in mice prone to the insuline-disrupting disease, report researchers from the University of Michigan Medical Center in Ann Arbor.

Richard Guytingo and his colleagues injected the vaccine into prediabetic mice aged 5 to 8 weeks. A month later, they extracted spleen cells from the mice and looked for immune cells called T-lymphocytes. Some T-lymphocytes, produced in the spleen, are believed to stimulate Type I diabetes by attacking the insulin-secreting islet cells in the pancreas. According to Guytingo, the vaccinated mice showed slower proliferation of these T-cells than did unvaccinated mice.

After three months, the researchers compared the actual islet cells of the vaccinated mice and the controls. The treated mice showed significantly less insulities, or inflammation of the islet cells -- a condition widely viewed as an early step toward diabetes.

"Potential applicability of BCG vaccination to the prevention of human autoimmune diabetes must be considered," the researchers assert. But they emphasize that many questions remain. For instance, results in mice don't necessarily apply to humans, and the timing and dosage of the vaccine and may be critical. Guytingo's group will next try to determine whether countries where children routinely receive BCG vaccinations have a lower incidence of Type I diabetes.