  Migration of cells can be characterized by two, prototypical types of motion:
individual and collective migration. We propose a statistical-inference
approach designed to detect the presence of cell-cell interactions that give
rise to collective behaviors in cell-motility experiments. Such inference
method has been first successfully tested on synthetic motional data, and then
applied to two experiments. In the first experiment, cell migrate in a
wound-healing model: when applied to this experiment, the inference method
predicts the existence of cell-cell interactions, correctly mirroring the
strong intercellular contacts which are present in the experiment. In the
second experiment, dendritic cells migrate in a chemokine gradient. Our
inference analysis does not provide evidence for interactions, indicating that
cells migrate by sensing independently the chemokine source. According to this
prediction, we speculate that mature dendritic cells disregard inter-cellular
signals that could otherwise delay their arrival to lymph vessels.
