ABSTRACT
Today, there is a growing interest in the intestinal microbiota and its relationship with the
host’s immunity. This is mainly due to two causes: first, the results obtained with
probiotics, which have been defined as live micro-organisms that confer a health benefit on
the host when consumed in adequate amounts (1), have shown interesting immunomo-
dulatory properties in humans (1-3). Second, the studies by Dutchmann and coworkers
(4) demonstrated for the first time, some years ago, that we are tolerant to our own
digestive flora. A breakdown of this state leads to inflammatory bowel diseases (IBD).
Consequently, the digestive flora can be considered as an organ belonging to the host’s just
as the spleen, heart, or brain. It plays an important role in the host’s protection, especially
by its actions on the immune system.
