Effects of cream on bactericidal and metabolic functions of bovine polymorphonuclear neutrophils.

The effects of cream on the bactericidal capacity and on selected metabolic characteristics of bovine blood polymorphonuclear leukocytes (PMN) were examined in vitro. These properties were also compared in blood PMN and PMN isolated from milk. Addition of 4% cream to the incubation medium reduced killing of Staphylococcus aureus by blood PMN. The PMN from milk were as bactericidal as blood PMN when incubated in a synthetic medium without cream. Cream reduced the phagocytosis-induced increment in O2 uptake in blood PMN. Compared to blood PMN in the absence of cream, PMN isolated from milk had reduced O2 uptake during phagocytosis. In all PMN preparations [14C]CO2 production from [1-14C]glucose and [6-14C]glucose was increased during phagocytosis. Rates of [14C]CO2 conversion from [1-C14]glucose were not significantly different among blood PMN, blood PMN plus cream, and milk PMN. Cream reduced [14C]CO2 conversion from [6-14C]glucose by blood PMN; milk PMN converted even less [6-14C]glucose to [14C]CO2 than did blood PMN in the presence of cream. Cream added to blood PMN preparations in the absence of other phagocytizable particles increased O2 uptake, increased (nonsignificantly) [14C]CO2 conversion from [1-14C]glucose, and reduced conversion from [6-14C]glucose. These studies confirm that cream reduces the bactericidal capacity of bovine PMN and reveal cream-induced alterations in selected metabolic pathways during phagocytosis. They show also that cream itself, in the absence of bacteria, alters PMN metabolism.