Regional variations in the distribution of small intestinal intraepithelial lymphocytes in alymphoplasia (aly/aly) mice and heterozygous (aly/+) mice

Age-dependent changes in intraepithelial lymphocytes (IELs) of the small intestine, cecum, and colon from young adult to aged mice

We previously reported the regional differences in the IELs present in the proximal (P), middle (M), and distal (D) parts of the small intestine, cecum (Ce), and colon (Co) of mice. In this study, we investigated the age-dependent changes in the regional differences of IELs from young adult to aged mice. In this experiment, 3-, 6-, 12-, 18-, and 24-month-old mice were examined. IELs were separately isolated from 5 parts of the intestines and analyzed by flow cytometry. Regional differences in the number and phenotype of IELs showed the same trends in all age groups. The number of IELs was highest in 6-month-old mice and then gradually decreased with age. As to IEL subsets, age-related changes were not seen except for a few subsets among the age groups. We conclude that age-related decreases in IELs in mouse small intestine may be one of the aging phenomena of the intestinal immune system. Such age-related decreases in IELs may be concerned with the increased liability to intestinal infections in the elderly.

Differences in intraepithelial lymphocytes in the proximal, middle, distal parts of small intestine, cecum, and colon of mice

We have previously reported the regional differences in the intraepithelial lymphocytes (IELs) present in the small intestine of mice. In this study, we further investigated these differences on the basis of our previous findings and studied the entire intestine, including the cecum and colon. Most of the significant differences in phenotypic compositions were found between the small and large intestines, although some differences were found among the different parts of the small and large intestines. In particular, the composition of the subsets in alphabeta T cells and gammadelta T cells clearly differed between the small and large intestines. For example, in alphabeta T cells, the percentages of double negative (DN) and CD8alphaalpha(+) cells were higher in the large intestine, that of CD8alphabeta(+) cells was higher in the small intestine, and those of CD4(+) and CD4(+) CD8alphaalpha(+) double positive (DP) cells were higher in the distal part of the small intestine. In gammadelta T cells, the percentage of CD8alphaalpha(+) cells was higher in the small intestine and that of DN cells was higher in the large intestine. These results indicate that the differences between IELs in the small and large intestines are discontinuous.

Regional variations in the distributions of small intestinal intraepithelial lymphocytes (IELs) in outbred laboratory mice (Mus musculus domesticus) and the inbred strain of mice established from Japanese fancy mice (Mus musculus molossinus)

Previously, we reported regional variations in small intestinal IELs of mice. In this study, we examined the regional variations of IELs in outbred laboratory mice (ddY: Mus musculus domesticus) and the inbred strain of mice established from Japanese fancy mice (JF1: Mus musculus molossinus). IELs were isolated from the proximal, middle and distal parts of the small intestine and analyzed by flow cytometry. The percentages of gammadelta T cells and alphabeta T cell subset of extrathymic origin were higher in the proximal part while the percentages of alphabeta T cell subset(s) of thymic origin were higher in the distal part in both ddY and JF1 mice. Such trends in regional variations of IELs were almost the same as those found in the inbred strains of laboratory mice in our previous reports. This strongly suggests that these regional variations of IELs may be common phenomena in Mus musculus species.

Regional variations in the distributions of small intestinal intraepithelial lymphocytes in germ-free and specific pathogen-free mice

Previously, we reported the regional variations in intraepithelial lymphocytes (IELs) in the small intestine of mice. To clarify the effects of intestinal bacteria on the distribution of IELs, regional variations in IELs were examined using germ-free (GF) and specific pathogen-free (SPF) BALB/cA mice. The small intestine was taken and divided equally into three parts (the proximal, middle, and distal parts). IELs were isolated from each part of the intestine, and the total number of IELs in GF mice was about one seventh of that in SPF mice. The decreased number of IELs in GF mice suggests that intestinal bacteria may be essential for local expansion of IELs. On the other hand, similar regional variations in IEL subsets observed in both GF and SPF mice, except for some subsets. The similarity of regional variations in GF and SPF mice indicates that the regional variations in IEL subsets may not fundamentally depend on intestinal bacteria.