Prevention of overt diabetes and insulitis in NOD mice by a single BCG vaccination.

A single intravenous injection of 0.25-1 mg of live BCG organisms at approximately 10 weeks of age produced a potent suppression of insulitis and overt diabetes in non-obese, diabetes-prone (NOD) female mice. Injection of 1 mg of BCG into younger mice, aged 5 weeks, was also very suppressive but the injection into older mice of 15 weeks was somewhat less suppressive. Spleen cell transfer from the BCG-vaccinated NOD mice prevented the occurrence of overt diabetes in the recipients, while the transfer from untreated donors did not. This indicates the generation of some type of suppressor cells in the BCG-vaccinated mice.