Parenteral nutrition (PN) significantly reduces the percentage of cells expressing CD4+CD25+ α4β7+ compared to chow (12% ± 2.3 vs. 25% ± 1.9 vs. , p < 0.05). Addition of bombesin (BBS) to PN (PN+BBS) significantly increased CD4+CD25+ α4β7+ lymphocytes in the lamina propria compared to PN (27% ± 2.4 vs. 12% ± 2.3, p < 0.05). Values are means ± SE. Flow cytometry gating progressed from the preceding parent population in the order of lymphocytes, CD3+, CD4+CD25+, and then α4β7+ cells.