Altered functional and immunophenotypical properties of neutrophilic granulocytes in postpartum cows associated with fatty liver

The intention of the study was to analyze the relationship between liver tr iacyl glycerol content (liver TAG content) and immunophenotypical and funct ional properties of polymorphonuclear neutrophilic granulocytes (PMN) of da iry cows in the peripartum period. We investigated characteristics of bovin e PMN from the blood and uterus of clinically healthy cows in the peripartu rient period. The numbers of circulating leukocytes and segmented granulocy tes continuously increased until parturition and declined afterwards to sta rting values. This was independent of the liver TAG content and mainly affe cted neutrophils. The liver TAG content exceeded 40 mg/g liver, the referen ce value, in 12 of 19 cows in the first two weeks postpartum. Increased liv er TAG contest, >40 mg/g, went in parallel with a reduced expression of fun ction-associated surface molecules on blood neutrophils (e.g. CD11b/CD18 = CR3 and CD11c/CD18 = CR4). Moreover, in cows with high liver TAG levels the antibody-independent and -dependent cellular cytotoxicity (AICC, ADCC) of blood PMN was markedly reduced. PMN also were less capable of ROS generatio n after stimulation with Phorbol Myristate Acetate (PMA). In comparison wit h contemporarily harvested blood PMN, neutrophils recovered from the uterin e lumen showed a decreased expression of 4/6 examined surface structures. O nly the expression densities of CR3 molecules and those detected by mAb IL- A110 were enhanced on uterine PMN. The cytotoxic capacity and the ROS gener ation were significantly lower for uterine PMN than for blood PMN. The resu lts suggest that increased liver TAG content in the first and second week a fter calving is associated with decreased functional capacities of PMN deri ved from blood and uterus. This may help to explain why cows who are too fa t at calving (who therefore have an increased liver TAG content) have a hig her incidence of infectious diseases such as endometritis. (C) 2000 by Else vier Science Inc.