Identification of γδT lymphocyte subsets that populate calf ileal 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 extent the mucosa becomes populated after birth. Single and dual fluorescence flow cytometry were used with monoclonal antibodies to bovine (Bo) CD molecules to identify lymphocyte subpopulations. Few ileal mucosal lymphocytes were present in calves at birth. However, by 1.5 weeks of age, the villi were populated with large numbers of lymphocytes, and by 3 weeks of age, the numbers had increased further. These included a prominent subpopulation of γδT cells. Several subsets of γδT cells populated ileal mucosa after birth. The predominant subset coexpressed BoCD2, and a smaller subset coexpressed BoCD8. WC1(+) γδT cells comprised the smallest subset. All γδT cell subsets coexpressed ACT2, a molecule expressed on activated WC1(+) and WC1(−) γδT cells from cattle.