A NEW MODEL SYSTEM FOR ENDOMETRITIS - BASIC CONCEPTS AND CHARACTERIZATION OF PHENOTYPIC AND FUNCTIONAL-PROPERTIES OF BOVINE UTERINE NEUTROPHILS

The intention of this study was to develop a model system of puerperal endometritis in cows, which would permit detailed analysis of compone nts and mechanisms relevant to the onset and development of this disea se. As the first essential step we examined the induction and migratio n of polymorphonuclear neutrophil granulocytes (PMNs) into the uterus under defined conditions. Migration of neutrophils into the uterus of healthy estrus synchronized heifers (n=8) was induced by intrauterine infusion of 50 ml of a 30 nmol/l solution of leukotriene B-4 (LTB(4)). Before and 24 h after the infusion, cells were flushed from the uteri ne lumen. In addition to total leukocyte counts, viability and morphol ogical differentiation of various leukocyte populations, phenotypic ch aracteristics of PMNs were monitored by means of quantitative immunofl uorescence using monoclonal antibodies. The capacity of PMNs to genera te reactive oxygen species (ROS) following activation with phorbol est er was measured using dihydrorhodamine 123. The phagocytic activity of PMNs was determined by their ingestion of fluorochrome labeled nonvia ble staphylococci. Most methods mentioned above were adapted to flow c ytometric analysis. The LTB(4) attracted selectively large numbers of PMNs into the uterus. In comparison with contemporarily harvested bloo d PMNs, neutrophils recovered from the uterine lumen showed changes in the expression of some but not all of their surface structures. Phago cytic activity of uterine PMNs was significantly lower when compared w ith that of blood PMNs. In contrast, the generation of ROS was not dif ferent between blood and uterine PMNs. Thus, the concept of inducing e ndometritis directly by local application of a physiological mediator of inflammation such as LTB(4) has been successful. This bovine model permits detailed analysis of migration of PMNs into the uterus and the ir behavior under defined conditions within the autologous system.