Intraepithelial lymphocytes in colon have similar properties to intraepithelial lymphocytes in small intestine and hepatic intermediate TCR cells.

Recently, properties of intraepithelial lymphocytes (IEL) in the colon (C-IEL) have been analyzed in comparison with those of IEL in the small intestine (SI-IEL). We compared the properties of C-IEL with those of SI-IEL and hepatic intermediate TCR cells, two other types of extrathymic T cells. C-IEL and intermediate TCR cells contain many NK1+T cells, although SI-IEL contain few. V gamma and V delta usage of C-IEL was the same as that SI-IEL, and that of intermediate TCR cells was different. C-IEL responded to Con A while SI-IEL did not. As to adhesion molecules, C-IEL include both extrathymic and thymus-originated type T cells. With age, TCR- alpha beta(+) CD4+ CD8+ cells do not increase among C-IEL but do increase among SI-IEL. IL-2R beta(+) or CD4- CD8- C-IEL increase as observed in the liver. These results indicate that these organ-specific T cells have different roles at their respective sites and that they may be of different lineages.