Preinfection In Vitro Chemotaxis, Phagocytosis, Oxidative Burst, and Expression of CD11/CD18 Receptors and Their Predictive Capacity on the Outcome of Mastitis Induced in Dairy Cows with Escherichia coli

Abstract

Four to 6 wk after parturition, 12 cows in second, fourth, or fifth lactation were experimentally infected in one gland with Escherichia coli. The capacity of chemotaxis, phagocytosis, oxidative burst, and expression of CD11/CD18 receptors to predict the severity of IMI was measured. Bacterial counts in the infected quarter, expressed as area under the curve, and residual milk production in the uninfected quarters were compared to determine severity of the infection. Although these two outcome parameters were highly negatively correlated, regression models with preinfection tests for leukocyte function fitted best with bacterial counts as an outcome parameter. Of the preinfection tests for leukocyte function, chemotaxis best predicted the outcome of the IMI that had been experimentally induced by E. coli.The number of circulating peripheral leukocytes just prior to inoculation was used to predict 52 and 45% of the severity of IMI for bacterial counts and residual milk production, respectively. As a categorical variable, parity predicted 75 and 56% of the severity of IMI expressed as bacterial counts and residual milk production, respectively. Because of the strong effect of parity on the outcome of the experimentally induced mastitis, analysis was performed to discriminate between second parity cows and older cows. Significant differences were found for the number of circulating peripheral leukocytes and for the expression of CD11b/CD18 and CD11c/CD18 receptors between younger and older cows. ( Key words: bovine, Escherichia coli, mastitis, leukocyte function test) Abbreviation key: AUC = area under the curve, PMN = polymorphonuclear neutrophil, RMP = residual milk production.

Hyperketonemia and the impairment of udder defense: a review

“…The severity of clinical mastitis after IMI is, however, less dependent on the functional capacity of blood phagocytes [3,11,115] than on the intra-mammary functional capacity of these cells. In the mammary gland, a low efficiency of PMN phagocytosis is caused by either ingestion of milk constituents, such as fat globules [25,76] and casein micelles [92,93], or a deficiency of opsonins in milk [76,83,85].…”

“…Migration of blood PMN between endothelial cells into the site of infection is dependent on the number of blood PMN and its migration capacity [98,114]. Low numbers of blood PMN pre-challenge are also related to increased severity of experimental Escherichia coli mastitis [57,114,115].…”

“…Regardless of bacterial species, both quantity and quality of polymorphonuclear leukocytes (PMN) in the udder are important components of udder defense in order to protect cows from clinical mastitis [10,11,18,46,72,97,109]. In experimental mastitis challenge studies, cows with lower chemotactic capacities of blood PMN also had a higher severity of mastitis indicated by bacteria counts in milk [13,56,57,115].…”

Local and systemic effects of endotoxin mastitis on the chemiluminescence of milk and blood neutrophils in dairy cows

“…Polymorphonuclear leukocytes (PMN) are important components of the cellular host defense in protecting cows against Escherichia coli infection within the mammary gland [5,15,19,21,39]. Acute E. coli mastitis in early lactating cows is sometimes accompanied by severe general clinical symptoms such as fever and a sudden decrease of milk production in non-injected (non-inflamed) quarters [16,24,37].…”

“…The intramammary defense against invading pathogens is highly dependent on the rate of PMN diapedesis into the infected quarters [16], their capacity to produce reactive oxygen intermediates (ROI) [15] and the number of circulating PMN prior to infection [15,21,37,39]. Chemiluminescence (CL) can be used to study the oxygen-dependent bactericidal system of PMN [1,9,23,27].…”