Influence of the perinatal period on bovine interferon production.

Interferon (IFN) production in cultures of leukocytes of calves immediately after birth, 2--3-day-old calves, dams and nonpregnant lactating cows was compared. For IFN induction Radom strain of Newcastle disease virus (NDV-R), phytohemagglutinin (PHA) and concanavalin A (ConA) were used. Cultures of newborn-calf peripheral blood mononuclear cells (PBMC) separated from blood by Ficoll-Hypaque density centrifugation or leukocytes cultivated by whole blood technique responded to all inducers used with a significantly lower IFN level than those of 2--3-day-old calves, dams and lactating cows. Although the mechanism of this phenomenon is not clear, our data connot rule out a defect of IFN synthesis in blood leukocytes of newborn calves. Spontaneous antiviral activity was detected in fetal membranes and in colostral leukocytes. Colostral leukocytes were efficient producers of IFN after induction with NDV-R, but less efficient than blood leukocytes after induction with PHA and ConA. Low response to PHA and ConA correlated with low number of lymphocytes in colostrum.