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P056. Similar phenotype and functional capacities of T lymphocytes in different anatomic locations of human intestine

A. Carrasco1, F. Fernandez Bañares1, M. Rosinach1, C. Loras1, M. Aceituno1, J. Espinos1, M. Forne1, J.M. Viver1, M. Esteve1

1Hospital Universitari MútuaTerrassa, Terrassa, Spain

Background: There is scarce information concerning T lymphocyte subpopulations in the normal intestine and their phenotypic and functional differences related to anatomic location. This knowledge is important in studies comparing normal and inflamed intestine in diseases involving different parts of the gastrointestinal tract. Aim: To asses if there are location related differences in T cell subpopulation and apoptosis in healthy intestine.

Methods: Ileocolonoscopy for colon cancer prevention was performed to 7 healthy subjects (age 48.6±7) and 10 biopsies were collected from terminal ileum, right and left colon. Flow cytometric analysis was performed to asses cell phenotype (CD3, CD4, CD8), Treg cells (CD25FoxP3), intracellular cytokines (IFNγ, IL‑17‑A), apoptosis (AnnexinV). Results were compared by using paired Friedman test.

Results: A significant decrease in the total cell count was observed in colon compared to ileum. Intracellular IFNγ+CD4+ were significantly increased, whereas CD8 apoptosis was significantly decreased in ileum as compared with colonic mucosa. An increase of Double Positive CD4+CD8+ T Cells, whereas Double negative CD4−CD8− T Cells were reduced in ileum compared to colon. There were no significant differences for the remaining lymphocyte subpopulations. The most remarkable results are shown in the table.

% FCM Median (IQ)IleumRight ColonLeft Colonp
Total lymphocyte recovery900000 (645000–2060000)665000 (450000–945000)513500 (300000–1015000)0.03
CD3+68.2 (42.2–89.1)81.3 (48.6–85.5)77.7 (62.4–85.4)0.40
CD4+34.0 (21.2–39.0)30.3 (21.2–43.3)35.7 (21.2–45.0)0.13
CD25+FoxP3+5.6 (3.2–7.4)4.2 (2.7–6.3)4.1 (1.4–4.9)0.36
IFNγ+2.0 (1.3–3.6)3.0 (0.8–7.8)2.4- (0.7–5.7)0.04
IL17A+1.0 (0.4–2.0)1.2 (0.6–4.8)1.8 (0.2–2.9)0.11
CD8+AnnexinV+14.4 (4.6–20.6)17.1 (9.8–28.3)18.7 (13.1–26.6)0.03
Double Positive CD3+CD4+CD8+8.4 (2.5–11.6)5.3 (1.4–6.9)4.9 (1.6–7.9)0.02
Double Negative CD3+CD4−CD8−3.8 (0.6–6.5)8.0 (4.7–12.5)7.1 (3.3–10.6)0.06

Conclusions: Phenotype and function of T lymphocytes are similar in different areas of the colon. A decreased apoptosis in ileum compared to colon was found. In addition, an increase of Double Positive Cells and a decrease of Double Negative Cells in ileum compared to colon was detected. Since these subpopulations have important regulatory functions of immune response, these differences should be taken into account in studies of intestinal inflammation.