Cross-talk between probiotic lactobacilli and host immune system.

The mechanism by which probiotic lactobacilli affect the immune system is strain specific. As the immune system is a multicompartmental system, each strain has its way to interact with it and induce a visible and quantifiable effect. This review summarizes the interplay existing between the host immune system and probiotic lactobacilli, that is, with emphasis on lactobacilli as a prototype probiotic genus. Several aspects including the bacterial-host cross-talk with the mucosal and systemic immune system are presented, as well as short sections on the competing effect towards pathogenic bacteria and their uses as delivery vehicle for antigens.