Dresden 2020 – scientific programme

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BP: Fachverband Biologische Physik

BP 10: Poster III

BP 10.17: Poster

Monday, March 16, 2020, 17:30–19:30, P2/3OG

Target size dependency of cellular resolution limits during phagocytosis — •Manuel Eisentraut, Adal Sabri, and Holger Kress — Biological Physics Group, Department of Physics, University of Bayreuth, Germany

Antibodies can interact with phagocytic receptors on macrophages and trigger signalling cascades which initiate phagocytosis. A large number of the molecular components of these signalling networks are well known, but it remains unclear how fast and how far the corresponding signals propagate in the cell.

To address this issues, we investigated the spatial spreading of phagocytic signalling by measuring how well cells can resolve whether one or two particles are attached to the cell membrane. In our experiments, we attach pairs of equally-sized polystyrene beads opsonized with antibodies to single macrophages. We were able to precisely control the distance of the beads during the attachment by utilizing holographic optical tweezers. The subsequent uptake into two separate or one joint phagosome was distinguished by analysing the intracellular particle trajectories after the uptake. We found that the probability for separate uptake is very high for large distances and very low for small distances, with a transition between these regimes at surface-to-surface distances of several hundreds of nanometers. A comparison between measurements with different bead sizes suggests that the separate uptake probability not only depends on the bead distance, but also on the total size of the target bead pair. Our results provide quantitative insights into the spatial spreading of signalling during phagocytosis.