intraepithelial lymphocytes interspersed between intestinal epithelial
cells form a large population of T cells, mainly CD8+, close to the i
ntestinal lumen. Together with lamina propria T cells and plasma cells
, they represent the effector limb of the gut-associated lymphoid syst
em. Recent data highlighting their original properties and their inter
actions with epithelial cells are reviewed; their contributions to imm
une defenses and gastrointestinal diseases in humans are discussed.