Autocrine signaling in 3 dimensions

A model of autocrine signaling in cultures of suspended cells was developed on the basis of the effective medium approximation. The fraction of autocrine ligands, the mean and distribution of distances traveled by paracrine ligands before binding, as well as the mean and distribution of the ligand lifetime were derived. Interferon signaling by dendritic immune cells were considered as an illustration.

Effective medium approximation. The three-dimensional suspension of partially absorbing cells is approximated by an effective medium that is characterized by reaction rate constant kb. Two typical trajectories: autocrine and paracrine.