Intestinal intraepithelial lymphocytes preferentially repopulate the intestinal epithelium

We have used C.B-17 severe combined immune deficiency (SCID)mice to study the repopulation of intestinal intraepithelialcells in these mice. We have found that intestinal intraepitheliallymphocytes (IELs) injected into SCID mice preferentially repopulatethe intestinal epithelium. About 5 weeks after injection wecan detect significant numbers of IEL in repopulated SCID mice.Repopulation occurs in {small tilde}70% of the injected miceand the amount of recovered cells per mouse is variable. Therecovered cells are of donor-type origin and exhibit a typicalIEL phenotype. The donor-type T lymphocytes that can sometimesbe found in other organs of IEL-repopulated SCID mice are generallyof low number. They are not stained with antibodies againstIEL-specific markers and their phenotypes appear to be moretypical for T cells normally found in these sites. In contrast,the intestinal epithelium of SCID mice cannot be efficientlyrepopulated with lymphocytes using cells of other organs includingthymocytes, Peyer's patch lymphocytes, and bone marrow cells.From our data we conclude that intestinal IELs are confinedto the intestinal epithelium and possibly contain a precursor-typecell that preferentially regenerates cells of its own population.