Effect of the oral administration of Lactobacillus brevis subsp. coagulans on interferon-alpha producing capacity in humans.

This study was designed to determine whether the oral administration of Lactobacillus brevis subsp. coagulans modulates immunological responses in human subjects, and whether there are differences in response between live and heat-treated preparations. The effect of the oral administration of Lactobacillus brevis subsp. coagulans (Labre) for 4 weeks on the interferon-alpha (IFN-alpha) producing capacity of apparently healthy subjects was evaluated. Sixty volunteers were divided into five groups for the determination of virus-induced IFN-alpha production in response to various doses of live and to heat-killed Labre. 2-5A synthetase activity was measured to detect trace amounts of IFN production. Routine blood tests were also performed to determine the state of health of the subjects involved in this study and to test any side effects of Labre treatment. The oral administration of live Labre showed a statistically significant increase in IFN-alpha production at 2 weeks (p < 0.05) and at 4 weeks (p < 0.05) in the group receiving 600 million bacteria/day and at 4 weeks (p < 0.05) in the group receiving 300 million bacteria/day. In particular, IFN-alpha production in those with initially low levels rose significantly when either 300 million or 600 million bacteria/day were ingested. Consumption of heat-killed Labre 300 million bacteria/day did not result in a statistically significant change in IFN-alpha production. The level of 2-5A synthetase activity remained the same in the control and experimental groups. Oral administration of live Labre significantly increased IFN-alpha production in a dose-dependent manner. Labre intake tended to be most beneficial in subjects with initially low levels of IFN-alpha production. Heat-treated Labre did not elicit a response similar to that of the live bacteria.