The inhibitory effect of the Chinese herb Ganoderma lucidum mycelium on gut immunoglobulin A responses to cholera toxin in mice

Five-week-old female C57BL/6J mice were fed AIN-93G diet containing 0, 0.5, 1, 3 and 5% (wt/wt) Ganoderma (G) lucidum mycelium for 4 wk. Mice were orally immunized with 5 μg cholera toxin (CT) on d 7 and d 21 of feeding period. The total IgA and specific anti-CT IgA level in luminal washes of small intestine, serum and fecal pellets as well as anti-CT IgG response in serum were determined by ELISA. The total IgA level generally was not affected by G. lucidum mycelium except in serum samples. By contrast, the anti-CT IgA antibody response was reduced in all the samples from mice fed diets containing G. lucidum mycelium except in the small intestine luminal washes of mice fed the diet containing 5% G. lucidum mycelium. The serum anti-CT IgG response was only decreased in mice fed 3% G. lucidum mycelium. Thus, G. lucidum mycelium reduced the mucosal specific IgA response of young adult mice orally immunized with CT.