Abstract
The concentration of 9,13-di-cis retinoic acid has been shown to be elevated in the circulation of calves and cows during the immediate postpartum period. In order to evaluate its immunomodulatory potential, responses of resting and pokeweed mitogen-stimulated bovine peripheral blood mononuclear leukocytes from neonatal calves to physiologic concentrations of 9,13-di-cis retinoic acid were evaluated in vitro.Mononuclear leukocytes were isolated at the same times from cows and their precolostral calves immediately after parturition and from non-pregnant heifers. Production of polyclonal IgM and interferon-? by resting and poke-weed mitogen-stimulated cultures of mononuclear leukocytes from neonates and adults was unaffected by 9,13-di-cis retinoic acid. 9,13-Di-cis retinoic acid, at 25 nM, significantly (P< 0.05) inhibited pokeweed mitogen-induced proliferation of mononuclear leukocytes from non-pregnant heifers, and had no effect on the proliferation of mononuclear leukocytes from the dams or their calves. These results indicate that 9,13-di-cis retinoic acid at physiologic concentrations has negligible effect on the proliferation and function of precolostral calf and adult bovine mononuclear leukocytes in vitro.