DIFFERENCES IN INTRAEPITHELIAL LYMPHOCYTE-T CELL SUBSETS ISOLATED FROM MURINE SMALL VERSUS LARGE-INTESTINE

Intraepithelial lymphocytes (IELs) have been extensively studied in th e murine small intestine. However, to date no studies have assessed IE L in the large intestine, despite the marked differences in function a nd lumenal environment. In the present study, we isolated IEL from bot h small and large intestine of three mouse strains (BALB/c, C3H/HeN, C 57BL/6) and determined the frequency of CD2, CD4, and CD8 expression o n CD3(+) IEL, as well as the frequency of alpha beta and gamma delta T CR usage and V beta distribution. Higher numbers of IEL/unit length we re always isolated from the small intestine (20-30 x 10(6)/5 mice) com pared with large intestine (1.1-2.5 x 10(6)/5 mice). Interestingly, IE L from the large intestine of all strains were predominantly alpha bet a TCR(+) whereas gamma delta TCR(+) IELs predominated in small intesti ne. Large intestinal IELs were mainly CD4(+), in both BALB/c and C3H/H eN mouse strains. IELs from large intestine of C57BL/6 mice were mainl y CD8(+); however, the CD4(+) subset was fourfold higher when compared with small intestine IEL. Potential functional differences between IE L subsets was assessed by determining the relative levels of mRNA for IL-1, 2, 4, 5, 10, IFN-gamma, TGF-beta, and TNF-gamma. Similar pattern s for IL-1, IFN-gamma and TNF-alpha were seen while more IL-2, IL-4, I L-5, and IL-10 mRNA was noted in large intestinal IEL. Stimulation of C3H/HeJ IEL with anti-CD3 also resulted in higher levels of IL-3/GM-CS F, IL-4, and IL-6 by IEL from large intestine. These results show that marked differences occur among the T cell subsets present in IELs fro m mouse small and large intestine.