FLOW CYTOMETRIC MEASUREMENT OF NEUTROPHIL ALKALINE-PHOSPHATASE BEFOREAND DURING INITIATION OF AN INDUCED ESCHERICHIA-COLI MASTITIS IN CATTLE

In 12 healthy cows, neutrophil alkaline phosphatase (NAP) activity was measured by flow cytometer before and during an experimentally induce d Escherichia coli mastitis, to study the role and increase of NAP in Gram-negative bacterial infections. Percentage of neutrophils containi ng alkaline phosphatase and intensity of NAP activity were measured. P reinfection percentage of neutrophils with enzyme activity varied betw een 64.0% and 84.4% and the intensity of enzyme activity was low in al l cows. After induction of infection, percentage of neutrophils with e nzyme activity showed a significant decrease on day 1 followed by an s ignificant increase on day 3. NAP intensity increased significantly on the second and third day after infection. This increase of intensity was significantly, positively correlated with the severity of infectio n. From this study we may conclude that variation in susceptibility to E. coli mastitis could not be explained by preinfection NAP levels. T he post-infection increase of NAP activity, that was found following a n induced infection was more a result of increased enzyme intensity pe r neutrophil, then from an increase of percentage neutrophils with enz yme activity. Furthermore, a strong correlation was found between NAP intensity and severity of inflammation. There was evidence that the mo re severely diseased animals showed stronger NAP intensity increase. ( C) 1998 Elsevier Science B.V.