Exploiting or overcoming the dome trap for enhanced oral immunization and drug delivery.

The microfold cells (M cells) residing in the outmost follicle-associated epithelia (FAE) of Peyer's patches capture foreign particles and hand over to sub-FAE lymphatics, where the particles are retained and disposed subsequently. A concept of "dome trap" is proposed to highlight the significance of this mechanism. For oral immunization, it is better to exploit the entrapment capacity to maximize immune response, whereas for drug delivery it is better to overcome the dome trap to transport drugs into the systemic circulation. By optimizing the size, shape, surface charges and surface properties of particles, either oral immunization or drug delivery can be potentially enhanced.