|Rajaraman, Veena - IA STATE UNIV., AMES, IA|
Submitted to: Journal of Nutritional Immunology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 5, 1996
Publication Date: N/A
Interpretive Summary: During the first months of life, calves are highly susceptible to a number of infectious diseases associated with significant economic losses to the US dairy and beef cattle producers. Scientific evidence suggests that under most conditions, vitamin A and related compounds have a beneficial effect on the function of the immune systems of many types of animals. A compound related to vitamin A, called 9,13-di-cis-retinoic acid, has been found at high levels in the blood of calves and their mothers shortly after birth. The biological significance of the elevated levels of this compound is unknown. However, closely related compounds have been shown to enhance the function of the immune system of adult dairy cows. This study considered the effects of 9,13-di-cis-retinoic acid on the function of specialized cells of the immune system of the calf, called lymphocytes. Based on the results of this study, this form of vitamin A appears to have negligible effects on the function of immune cells from the young calf. One of the other vitamin A compounds must be responsible for the beneficial activity of vitamin A. Discovery of the beneficial compound will allow development of drugs to improve the newborn animal's immune system and help prevent or reduce the severity of diseases such as diarrhea and pneumonia.
Technical 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-gamma by resting and pokeweed 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, significan (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 physiolog concentrations has negligible effect on the proliferation and function of precolostral calf and adult bovine mononuclear leukocytes in vitro.