Table 1.

The effect of commensal bacteria on the development of the immune system.

Inhibits epithelial NF-kB activation and inflammatory gene expression
Activates CD4 cells in Peyer's patches
Activates CD8 or natural killer cells in intraepithelial leukocyte spaces
Increases numbers of T and B cells, including CD86-positive cells
Organizes the special relationships between T, B, and dendritic cells in the Peyer's patches
Increases the numbers of microfold cells
Increases IgA producing B cells
Hypertrophies Peyer's patches and the development of germinal centers