IDENTIFICATION OF GAMMA-DELTA-T LYMPHOCYTE SUBSETS THAT POPULATE CALFILEAL MUCOSA AFTER BIRTH

Ileal intraepithelial and lamina propria lymphocytes from newborn, 1.5 -week-old, and 3-week-old calves were compared to determine to what ex tent the mucosa becomes populated after birth. Single and dual fluores cence flow cytometry were used with monoclonal antibodies to bovine (B e) CD molecules to identify lymphocyte subpopulations. Few ileal mucos al lymphocytes were present in calves at birth. However, by 1.5 weeks of age, the villi were populated with large numbers of lymphocytes, an d by 3 weeks of age, the numbers had increased further, These included a prominent subpopulation of gamma delta T cells, Several subsets of gamma delta T cells populated ileal mucosa after birth. The predominan t subset coexpressed BoCD2, and a smaller subset coexpressed BoCD8. WC l+ gamma delta T cells comprised the smallest subset, All gamma delta T cell subsets coexpressed ACT2, a molecule expressed on activated WCl + and WCl- gamma delta T cells from cattle.