Table 2.

Compartments of the immune system modeled by ENISI.

Tissue type	Description
Lumen	The inner open space of a tubular organ such as the stomach or intestine.
Epithelium (Ep)	The thin monolayer of epithelial cells separating the lumen and LP. The epithelium is composed of several subsets of epithelial cells, but intraepithelial lymphocytes can also be present.
Lamina propria (LP)	The connective tissue underlying the Ep where most of the immune cells associated with the stomach mucosa reside. LP is an effector site.
Draining lymph nodes (LNs)	The secondary lymphoid organs draining the gastrointestinal tract. The LNs are inductive sites of the mucosal immune system; where immune responses are induced.
Blood	The source for the monocytes such as Macrophages, dendritic cells, and neutrophils.