Regensburg 2016 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 49: Posters - Cell Mechanics and Migration & Physics of Cancer

BP 49.3: Poster

Mittwoch, 9. März 2016, 17:00–19:00, Poster C

Phagosomes of different size show qualitatively different transport characteristics — •Steve Keller, Konrad Berghoff, and Holger Kress — Department of Physics, University of Bayreuth, Germany

Phagocytosis is one of the key processes of the mammalian immune system. The uptake of pathogens is typically followed by a transport of the phagosomes towards the perinuclear region as part of their maturation process. This process shows high phagosome-to-phagosome variations that are not fully understood. We hypothesize that the phagosome size has an influence on the maturation process by directly influencing the transport characteristics. We test this hypothesis by tracking the transport of phagosomes with different diameters ranging from 1 μm to 3 μm inside macrophages. We show that larger phagosomes are transported more persistently towards the nucleus and that they exhibit less backwards motion. We furthermore found that the effective transport velocity towards the nucleus increases with the phagosome size despite nearly equal instantaneous velocities for the different sizes. In addition, we investigated the microtubule density distribution in macrophages. We found that density differences between the nucleus-facing side of phagosomes and the opposite side can explain part of the observed transport characteristics. Our findings suggest that a simple size-dependent cellular sorting mechanism might exist that supports inward transport of large phagocytosed bacteria for facilitating their digestion and that simultaneously supports outward transport of small bacterial fragments for example for antigen presentation.