Bovine IL-18 ELISA: detection of IL-18 in sera of pregnant cow and newborn calf, and in colostrum.

In this study, we examined the concentration of bovine IL-18 in the sera of pregnant cows, their fetuses and newborn calves, and in colostrum in order to examine the role of IL-18 in bovine pregnancy and the neonatal period. A sandwich-ELISA to quantify bovine IL-18 was established using anti-porcine IL-18 monoclonal antibodies, which cross-reacted with bovine IL-18, and used it to measure the concentration of bovine IL-18 in the sera of pregnant cows, their fetuses and newborn calves, and in colostrum. Significant levels of IL-18 were detected in the sera of pregnant cows, but not in the sera obtained from the corresponding fetuses, umbilical arteries and veins. After birth, IL-18 levels in the sera of 1-day and 1-week old calves were low, and significantly increased in the sera of 1-month and 4-month old calves. IL-18 was also detected in colostrum, with the concentration of IL-18 in the first colostrum produced after delivery being the highest, and then decreasing depending on the number of milkings. Furthermore, the serum IL-18 concentration of newborn calves was increased after the oral administration of colostrum. These results suggest that IL-18 during bovine pregnancy and in the newborn period may play important roles in the maintenance of pregnancy and in the maturation of neonatal immunity.