Blastogenic response of peripheral blood lymphocytes from multiparous pregnant ewes.

The immunocompetence of pregnant multiparous ewes was investigated with respect to the blastogenic response of peripheral blood lymphocytes of (PBL) to three mitogens: PHA, Con A, and PWM. The profile of PBL responses shows 1) progressive suppression at 36 and 66 days of gestation, 2) enhanced response at 97 days of gestation, which approaches the mean values observed at the premating period, and 3) a redecline of the response at 137 days of gestation to depressed values lower than observed at 36 and 66 days of gestation. The results suggest that mitogen-treated lymphocytes were depressed and that the immunodepressive factor(s), which can influence lymphocytes at the systemic level, may be involved in the maintenance of the ovine fetal semiallograft.