LAMINA PROPRIA T-CELL SUBSETS IN THE SMALL AND LARGE-INTESTINE OF EUTHYMIC AND ATHYMIC MICE

We investigated lamina propria T cells from the small intestine (jejunum/ileum) and the large intestine (colon) of euthymic (BALB/c, C.B-17, C57BL/6) and athymic (C57BL/6 nu/nu; BNX bg/bg nu/nu xid/xid) mice. CD3(+) T cells represented about 40% of the lamina propria lymphocytes (LPL) from the small or the large intestine of euthymic mice, and 20-30% of the LPL populations from the small or large intestine of athymic mice. In the lamina propria T cell population of the small intestine, 85% were of the alpha beta lineage in euthymic mice, but only 40% were of the alpha beta lineage in athymic mice. T cells of the gamma delta lineage were thus more frequent than T cells of the alpha beta lineage in the intestinal lamina propria T cells of extrathymic origin. CD4(+) T cells represented 40% of the lamina propria T cells in the small as well as in the large intestine of euthymic mice, and 20-30% of the T cells in the lamina propria of the nude mouse gut. In euthymic mice, 40% of the T cells in the small intestine lamina propria, and 30% of the T cells in the colonic lamina propria were CD8(+). In intestinal lamina propria T cell populations of athymic mice, the CD8(+) T cell population was expanded. Most (60-70%) CD8(+) T cells in the lamina propria of the small and the large intestine of euthymic and athymic mice expressed the homodimeric CD8 alpha(+)beta(-) form of the CD8 coreceptor. A fraction of 15-20% of all CD3(+) T cells in the lamina propria of the small and the large intestine of euthymic and athymic mice were 'double negative' CD4(-)CD8(-). A large fraction of the TCR alpha beta(+) T cells in the colonic lamina propria (but not in the small intestine lamina propria) of euthymic mice expressed the CD2 and the CD28 costimulator molecules, the adhesion molecule LECAM-1 (CD62 L), and could be activated in vitro by CD3 ligation. These data reveal a considerable heterogeneity in the surface phenotype and the functional phenotype of murine lamina propria T cells.