PHAGOCYTIC ACTIVITY OF BOVINE LEUKOCYTES DURING PREGNANCY

  • 1 January 1976
    • journal article
    • research article
    • Vol. 40  (1) , 111-116
Abstract
The phagocytic competence, measured as the total number of polymorphonuclear [PMN] leukocytes per cubic millimeter which phagocytosed Staphylococcus aureus strain 321 in vitro, was determined in 8 cows during complete pregnancies. Such leukocytes are referred to as active PMN. There was a gradual decline in the number of these cells from conception to a minimum between the 16-20th wk of pregnancy, followed by a steady increase to the cessation of lactation when a marked drop occurred; then there was an increase to a maximum during the 2nd wk prepartum. From this maximum there was a rapid decrease to an absolute minimum during the 1st wk after parturition. From the 2nd wk post-partum there was a gradual increase to conception. The correlation coefficient (r) of numbers of active PMN with time before conception was -0.474 (P = 0.01). There were significant differences (P = 0.01) in numbers of active PMN among the 8 cows. The cows fell into 2 groups, one with significantly more active PMN (P = 0.001) than animals in the 2nd group. The between cow differences may have been due to age (the cows with the highest numbers of circulating active PMNs were younger than those in the other group) or the combined stress of pregnancy and lactation (cows which were both pregnant and milking had the lowest numbers of active PMN).