BLOOD POLYMORPHONUCLEAR LEUKOCYTE CHEMOTAXIS DURING EXPERIMENTAL ESCHERICHIA-COLI BOVINE MASTITIS

The relationship between the severity of experimental Escherichia coli mastitis and the chemotactic response of blood polymorphonuclear leuk ocytes was investigated before and during mastitis. Experimental E. co li mastitis was induced in 10 healthy cows by inoculation of the rear right quarters with 10(3) cfu of E. coli. Cows were classified into tw o groups based on the severity of the mastitis. Bacterial growth in th e inoculated quarter was used as parameter that indicated severity. Be fore and during experimental mastitis, the chemotactic response and th e number of circulating polymorphonuclear leukocytes were greater for the moderately diseased cows than for the severely diseased cows. Duri ng the first 24 h of the experimental mastitis, the chemotactic respon se of polymorphonuclear leukocytes decreased in both groups. Recovery of the chemotactic response of white blood cells was more rapid in mod erately diseased cows than in severely diseased cows. Possibly, the la rger proportion of band neutrophils (the less chemotactically active b and neutrophils) partially accounts for the lower chemotactic response of the circulating polymorphonuclear leukocytes during experimental m astitis in the severely diseased cows.