PREINFECTION CHEMOTACTIC RESPONSE OF BLOOD POLYMORPHONUCLEAR LEUKOCYTES TO PREDICT SEVERITY OF ESCHERICHIA-COLI MASTITIS

Experimental mastitis was induced by inoculating rear right quarters o f 10 healthy cows with 10(3) cfu of Escherichia coli. The chemotactic responses of peripheral blood polymorphonuclear leukocytes at d -6, -5 , -2, -1, and immediately prior to inoculation were measured. Chemilum inescence of polymorphonuclear leukocytes was measured immediately pri or to inoculation. Severity of the experimental mastitis was assessed by bacterial growth in the inoculated quarters. Results of this study indicated that severity of the experimental mastitis may be predicted by the chemotactic response in vitro of polymorphonuclear leukocytes i solated from the peripheral blood at d 2, d 1, and immediately prior t o inoculation. The number of circulating polymorphonuclear leukocytes immediately prior to inoculation also showed a negative relationship w ith the severity of mastitis. No relationship existed between preinfec tion chemiluminescence of polymorphonuclear leukocytes and the severit y of the experimental mastitis. Preinfection chemotactic response of p olymorphonuclear leukocytes and preinfection numbers of circulating po lymorphonuclear leukocytes appeared to be valuable as predictors of se verity of experimental E. coli mastitis in cows.