Effect of age on MAIT cell abundance. Abundance of MAIT cell TCRα chain transcripts per constant region transcripts was measured by qPCR in tissues from calves of three different age groups: neonatal, 3-week old and 3-month old. Results are presented as quantities of MAIT TCRα expressed as a percentage of total α chain transcripts, and represent the mean of three identical reactions run for each tissue sample. Mesenteric lymph nodes were not assessed in two out of three 3-month old. Per LN: peripheral lymph node; Mes LN: mesenteric lymph node; SI wall: small intestinal wall; LI wall: large intestinal wall.