To investigate this, The researchers led by Daniel Irimia from at Massachusetts General Hospital (Harvard Medical School) designed a microfluidic platform in which the migration of neutrophils in response to chemical attractants could be observed. They saw that over 90 per cent reversed their direction and could move as far as one millimetre away from the action site. This remigration was able to be reinforced by adding the immunomodulator lipoxin A4, which helps to shut down the inflammatory response.

The researchers were able to use the microfluidic model to show that the accumulation of neutrophils on inflammation sites depends on the balance of three simultaneously occurring processes: chemotaxis along a diffusion gradient, remigration following mechanical principles and a movement stop triggered by phagocytosis.

Hamza, B., Wong, E., Patel, S., Cho, H., Martel J. & Irimia, D. (2014): Retrotaxis of human neutrophils during mechanical confinement inside microfluidic channels. Integrative Biology 6: 175-183. The Royal Society of Biochemistry. DOI: 10.1039/c3ib40175h