Biodegradable microparticles for oral immunization.

Ovalbumin (OVA) was entrapped in poly(lactide-co-glycolide) microparticles and administered to mice. Following intraperitoneal immunization, the microparticles induced both proliferative T-cell responses and cytotoxic T-cell responses in spleen cells. Following oral immunization, the mean salivary IgA antibody response to microparticles was significantly greater than the response to soluble OVA (p < 0.0001). Serum IgG antibody levels were also significantly greater in the group administered microparticles (p < 0.001). Cholera toxin B subunit was also entrapped in microparticles. Following oral immunization in mice, specific antibody-secreting cells were detected both in the spleens and in the mesenteric lymph nodes.