Effects of probiotic bacteria on humoral immunity to Candida albicans in immunodeficient bg/bg-nu/nu and bg/bg-nu/+ mice.

Germfree beige-nude ( bg/bg-nu/nu) and beige-heterozygous ( bg/bg-nu/+) mice were colonized with a pure culture of Candida albicans or with a probiotic bacterium (Lactobacillus acidophilus, Lactobacillus reuteri, Lactobacillus casei, or Bifidobacterium infantis). Probiotic-colonized mice were subsequently challenged orally with C. albicans. The effect of prior colonization with probiotic bacteria on the antibody responses of the immunodeficient mice to alimentary tract colonization with C. albicans was compared to the antibody responses of the gnotobiotic mice colonized only with C. albicans. This study demonstrated that, although the probiotic bacteria did not induce a vigorous antibody response to their own antigens, they altered the antibody responses of mice to C. albicans. In T cell competent bg/bg-nu/+mice, B. infantis enhanced and focused IgG1, IgG2A, and IgA responses to C. albicans antigens. Some of the probiotic bacteria also enhanced the IgG1 and IgG2A antibody responses of bg/bg-nu/nu mice to C. albicans antigens. This study not only shows the value of gnotobiotic animal models in demonstrating that probiotic bacteria can affect the capacity of mice to form antibodies to C. albicans, but it also points out their usefulness in comparing the capacity of different probiotic bacteria to produce beneficial health effects in mice.