Submitted to: Joint Meeting of the ADSA, AMSA, ASAS and PSA
Publication Type: Abstract Only
Publication Acceptance Date: 2/18/2006
Publication Date: 7/9/2006
Citation: Lippolis, J.D., Reinhardt, T.A., Goff, J.P., Horst, R.L. 2006. Neutrophil extracellular trap formation: an important neutrophil killing mechanism that is not inhibited in milk [abstract]. American Dairy Science Association-American Society of Animal Science 2006 Joint Annual Meeting. p. 94.
Technical Abstract: Neutrophils play a crucial role in protecting the mammary gland against bacterial infections. However, neutrophils incubated in milk have a decreased ability to kill bacteria in vitro and a decreased capacity to generate reactive oxygen species upon stimulation. Recently, a new neutrophil bacterial killing mechanism was described. When stimulated, human neutrophils release nuclear and granule material, and this extracellular material form webs that act as nets to trap and kill bacteria. We now show that bovine neutrophils form extracellular nets when stimulated. Furthermore, neutrophil extracellular traps can be formed even when neutrophils have been incubated for up to 6 hours in milk prior to stimulation. Extracellular nets formation in milk is not different from net formation in media. Stimulation of neutrophils with bacteria common to mammary gland infections leads to the formation of the neutrophil extracellular nets in milk or culture media. In fact, some bacteria were able to stimulate enhanced formation of extracellular traps in milk compared to culture media. In contrast to other neutrophil functions that are inhibited by milk, such as phagocytosis and oxidative burst, neutrophil extracellular traps may be an important innate immune mechanism in mammary infections because this ability remains intact in the milk environment.