γδ-TCR + CD2 - lymphocytes are recruited into bovine mammary gland after stimulation

γδ-T-Cell Receptor (TCR) lymphocytes were detected in mammary gland lavages collected from 10 clinically healthy virgin heifers before and after intramammary stimulation with synthetic muramyl dipeptide analogue. Using two-colour flow cytometry, CD2 + and CD2 - subsets of γδ-TCR lymphocytes were analyzed. CD2 + γδ-TCR lymphocytes markedly prevailed over CD2 - cells in intact mammary gland: 88.9 ± 4.9% of γδ-TCR lym- phocytes were CD2 + . After stimulation, neutrophils and γδ-TCR lymphocytes were recruited into the mammary gland. Among γδ-TCR lymphocytes, CD2 - cells were mainly responsible for their expansion. After stimulation, 60.8 ± 13.4% of γδ-TCR lymphocytes were CD2 + (P < 0.01 when compared with mammary gland lavages before stimulation). It follows from the present study that the cells seem to be involved in the first phase of a response to an infection affecting mammary gland.